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Taxonomy of the genus Malus Mill. (Rosaceae) with emphasis on the cultivated apple, Malus domestica Borkh.
Abstract
Twenty-nine Malus species, 12 M. domestica cultivars and representative outgroup taxa were chosen for sequence analysis of the internal transcribed spacer of nuclear
ribosomal DNA and the matK region of the chloroplast genome, in order to develop an explicit phylogenetic hypothesis for the genus and identify potential
germplasm donors to the domesticated apple, M. domestica. Maximum parsimony analysis generated nuclear and chloroplast cladograms that provide reasonable resolution of sub-generic
groups, as recognised in classifications. All of the close relatives of M. domestica occur in a poorly resolved series Malus clade. Two matK duplications were found, one in series Malus and the other in most M. domestica cultivars and one Central Asian M. sieversii accession.
... The genus Malus Mill. comprises of 25 to 47 species, depending on the rank given to several taxa and the acceptance of putative hybrids (Robinson et al., 2001). Malus classifications differ primarily in the taxonomic level at which infrageneric groupings of species are recognised. ...
... Currently, the most widely accepted theory, based mainly on morphological and molecular evidence, points to Malus sieversii (Lebed.) as the most likely main maternal wild ancestor of domestic apples (Harris et al., 2002;Robinson et al., 2001). A highly diverse apple crop wild relative, Malus sieversii is native to Central Asia. ...
... Malus sylvestris (L.) Mill. is the only indigenous wild apple species in Middle Europe. The distribution of M. sylvestris spreads from South-Scandinavia to the Iberian Peninsula and from the Volga to the British Isles (Robinson et al., 2001). Within its distribution area, the European wild apple is extremely rare and declared as endangered species (Kleinschmit and Stephan, 1997). ...
In Germany, all activities regarding fruit genetic resources management are based at the German National Program for Genetic Resources of Agricultural and Horticultural Plants. In the Fruit Genebank of the Julius Kühn-Institut, Institute of Breeding Research on Fruit Crops, Malus is the most prominent collection, consisting of 816 cultivars and 572 wild species accessions. The Malus accessions were expanded substantially through expeditions to the centers of origin. Field trips were undertaken to the Caucasus, where 1,167 seedlings of Malus orientalis originating from 247 accessions were collected and are now available for extensive phenotypic and molecular evaluation. Since fruit species are mainly vegetatively propagated crops, they need to be maintained in field collections, which is expensive. Duplication of genebank collections is necessary to prevent complete loss of genetic resources due to climate change, biotic and abiotic disasters and can be any useful combination of field plantings at locations other than the main collection, in vitro culture or cryopreservation. The 575 cultivars selected for the decentralized network of the German Fruit Genebank are to be duplicated at a second site as field collection within this network; 88% are realized. The Malus wild species accessions are held exclusively at the Fruit Genebank in Dresden-Pillnitz. Twenty-nine percent of these accessions have been duplicated by means of cryopreservation using the dormant bud method. Germplasm collections are valued for their diversity and their availability. Based on results obtained from several comprehensive characterisation and evaluation projects, the importance of these genetic resources in breeding research and for future apple breeding programs is clear. All points are significant contributions to the National Program for Genetic Resources of Agricultural and Horticultural Crops in Germany and so contribute to the realisation of a global strategy for Malus. This paper provides a review of the current status of ex situ conservation of Malus in Germany at the German Fruit Genebank.
... This has been bolstered by technological advancements that have enabled generating haplotyperesolved genomes of different progenitor species including M. sieversii and M. sylvestris (Sun et al., 2020). The Malus genus consists of 25 to 47 recognized species and additional hybrids (Robinson et al., 2001). Of those species, M. fusca and the other North American natives have been isolated from Asian and European gene pools used in the domestication of apple (Volk, 2019). ...
... We also performed gene synteny analysis with two wild progenitors of domesticated apple, M. sieversii and M. sylvestris (Sun et al., 2020). Comparisons of chloroplast genomes indicate that M. fusca is closely related to these species, which suggests Asiatic origins for M. fusca (Nikiforova et al., 2013;Robinson et al., 2001; 2015; Volk, Henk, et al., 2015). Thus perhaps, these wild species were only recently separated geographically by the submersion of the Beringia land bridge, that connected Asia to North America (Routson et al., 2012;Williams, 1982). ...
... For example, several inversions were observed on chromosome 03 that were shared between M. fusca and the two other wild apples, but the translocation between M. fusca chromosome 16 and M. sieversii chromosome 13 was specific to that comparison. Taken together, the relatively high whole-genome synteny and limited macro-variations support the Asiatic origins of M. fusca (Nikiforova et al., 2013;Robinson et al., 2001; Volk, Henk, et al., 2015). More population genetic work, focused on whole genome evolution, should be performed in the future to better understand the relationship between these wild species. ...
The Pacific crabapple (Malus fusca) is a wild relative of the commercial apple (Malus x domestica). With a range extending from Alaska to Northern California, M. fusca is extremely hardy and disease resistant. The species represents an untapped genetic resource for the development of new apple cultivars with enhanced stress resistance. However, gene discovery and utilization of M. fusca have been hampered by the lack of genomic resources. Here, we present a high-quality, haplotype-resolved, chromosome-scale genome assembly and annotation for M. fusca. The genome was assembled using high-fidelity long-reads and scaffolded using genetic maps and high-throughput chromatin conformation capture sequencing, resulting in one of the most contiguous apple genomes to date. We annotated the genome using public transcriptomic data from the same species taken from diverse plant structures and developmental stages. Using this assembly, we explored haplotypic structural variation within the genome of M. fusca, identifying thousands of large variants. We further showed high sequence co-linearity with other domesticated and wild Malus species. Finally, we resolve a known quantitative trait locus associated with resistance to fire blight (Erwinia amylo-vora). Insights gained from the assembly of a reference-quality genome of this hardy wild apple relative will be invaluable as a tool to facilitate DNA-informed introgression breeding.
... For example, Likhonos (1974) considered only eight species, while Ponomarenko (1986) recognized 78 species. Disagreements over species boundaries and diversity are also reflected in the recognition of various subspecies resulting from cross-compatibility in intraspecific and interspecific hybridization, and apomixis ubiquitous during the evolution of the genus (Robinson et al. 2001). Furthermore, a narrow species concept held by some Chinese taxonomists during the 1980s resulted in additional confusion regarding species boundaries (Hus & Gu 1986;Hus 1998). ...
... Incongruence between morphological and genetic data has been apparent in recent taxonomic studies (Yu 2000;Robinson et al. 2001;Forté et al. 2002;Huh 2007;Potter et al. 2007;Lo et al. 2012). For example, amplified fragment length polymorphism (AFLP) was employed for estimating genetic relationships within Malus, resulting in thirty-three species being classified into four and five groups by the UPGMA and Wanger method, respectively (Yu 2000). ...
... from different localities did not group together. Phylogenetic analysis based on internal transcribed spacer (ITS) and chloroplast matK gene sequences divided Malus into three clades (i.e., section Malus group, section Sorbomalus group, and basal taxa) (Robinson et al. 2001). Sections Eriolobus and Docyniopsis were included to ensure the monophyly of the genus. ...
A revision of the wild species in the genus Malus Mill. (Rosaceae) is presented based on numerical analyses and specimens from herbaria around the world, while cultivated species such as Malus domestica (Suckow) Borkh. are not included because of their complicated domestication history. Infra- and interspecific morphological variation and species delimitation are clarified based on Principal Component Analyses (PCA) and Cluster Analyses (UPGMA). We found that several morphological characters traditionally used to distinguish species have limited taxonomic value because of high phenotypic variation or plasticity. There is a substantial conflict between traditional morphological and genetic taxonomic concepts, and as a result species lineages are often morphologically indistinguishable. None of the analyses supports the recognition of infraspecific categories in Malus transitoria (Batalin) C.K.Schneid. and interspecific categories between Malus doumeri (Bois) A.Chev. and Malus leiocalyca S.Z.Huang. Based on our analyses, we recognize 26 wild species in the genus, and propose seven new synonymies.
... Furthermore, in the last decades, plant systematists in Rosaceae have struggled to resolve the phylogenetic relationships and evolutionary history between Malus and its relatives. Robinson et al. (2001) first used molecular evidence (plastid matK and nuclear ribosomal internal transcribed spacer (nrITS) sequences) to explore the phylogenetic relationships of five sections sensu Rehder (1940). Subsequently, phylogenetic studies on Malus and its close relatives used more plastid and nrITS sequences (Lo and Donoghue, 2012), whole plastome and/or entire nuclear ribosomal DNA (nrDNA) (Jin, 2014;Zhang et al., 2017;Liu et al., 2020a), and transcriptomic data set . ...
... However, Lo and Donoghue (2012) produced a monophyletic Malus s.l. based on 11 plastid regions as Robinson et al. (2001) did using matK regions ( Figure 1A, B). Generally, phylogenetic relationships within Malus s.l. are not fully resolved, particularly along the backbone of the phylogeny. ...
... Contrasting this New World origin hypothesis, Jin (2014) proposed an alternative hypothesis of East Asian origin based on biogeographic analyses using complete plastome data. Jin (2014) (Robinson et al., 2001), (B) 11 plastid coding and non-coding regions (Lo and Donoghue, 2012), (C) whole plastome (Jin, 2014), (D) whole plastome . (E) whole plastome (Liu et al., 2020a), (F) nuclear ITS sequence (Robinson et al., 2001), (G) nuclear ITS sequence (Lo and Donoghue, 2012), (H) transcriptome , (I) entire nrDNA sequences (Liu et al., 2020a). ...
Phylogenomic evidence from an increasing number of studies has demonstrated that different data sets and analytical approaches often reconstruct strongly supported but conflicting relationships. In this study, 785 single‐copy nuclear genes and 75 complete plastomes were used to infer the phylogenetic relationships and estimate the historical biogeography of the apple genus Malus sensu lato, an economically important lineage disjunctly distributed in the Northern Hemisphere and involved in known and suspected hybridization and allopolyploidy events. The nuclear phylogeny recovered the monophyly of Malus s.l. (including Docynia); however, the genus was supported to be biphyletic in the plastid phylogeny. An ancient chloroplast capture event in the Eocene in western North America best explains the cytonuclear discordance. Our conflict analysis demonstrated that ILS, hybridization, and allopolyploidy could explain the widespread nuclear gene tree discordance. One deep hybridization event (Malus doumeri) and one recent event (Malus coronaria) were detected in Malus s.l. Furthermore, our historical biogeographic analysis integrating living and fossil data supported a widespread East Asian‐western North American origin of Malus s.l. in the Eocene, followed by several extinction and dispersal events in the Northern Hemisphere. We also propose a general workflow for assessing phylogenomic discordance and biogeographic analysis using deep genome skimming data sets.
... The genus Malus Mill. comprises 25-47 species, depending on the taxonomic classification (Robinson et al., 2001). While several Malus species are indigenous to Asia, Malus sylvestris (Mill.) is the only indigenous wild apple species in Central Europe. ...
... While several Malus species are indigenous to Asia, Malus sylvestris (Mill.) is the only indigenous wild apple species in Central Europe. The spatial distribution of this European crabapple ranges from South Scandinavia to the Iberian Peninsula and from the Volga to the British Isles (Robinson et al., 2001). Despite this vast distribution area, M. sylvestris is very rarely seen and in fact endangered in most European countries (Bitz et al., 2019;Coart et al., 2006;Höltken et al., 2014;Larsen et al., 2006;Reim et al., 2012Reim et al., , 2013Wagner et al., 2014). ...
... Within the genus Malus, shared haplotypes were also identified in studies including numerous apple individuals of different cultivars and species (Savolainen et al., 1995;Volk et al., 2015). M. × domestica is known to be an admixed species from a number of progenitor species such as M. sieversii, M. orientalis, M. sylvestris, and M. prunifolia (Cornille et al., 2013;Robinson et al., 2001;Velasco et al., 2010;Volk et al., 2015). Thus, shared haplotypes may reflect the historical introgression between different Malus species due to gene flow or retention of ancestral polymorphisms (Koopman et al., 2007;Nevill et al., 2014;Volk et al., 2015). ...
Malus sylvestris (Mill.) is the only indigenous wild apple species in Central Europe. Agriculture, forestry, and urbanization increasingly endanger Malus sylvestris natural habitats. In addition, the risks of cross-hybridization associated with increase in the cultivation of the domesticated apple Malus × domestica (Borkh.) threaten the genetic integrity of M. sylvestris. The present study investigated the number of hybrids, genetic diversity, and genetic structure of 292 putative M. sylvestris that originate from five different natural M. sylvestris populations in Saxony, Germany. All samples were genetically analyzed using nine nuclear microsatellite markers (ncSSR) and four maternally inherited chloroplast markers (cpDNA) along with 56 apple cultivars commonly cultivated in Saxony. Eighty-seven percent of the wild apple accessions were identified as pure M. sylvestris. The cpDNA analysis showed six private haplotypes for M. sylvestris, whereas three haplotypes were present in M. sylvestris and M. × do-mestica. The analysis of molecular variance (AMOVA) resulted in a moderate (ncSSR) and great (cpDNA) variation among pure M. sylvestris and M. × domestica individuals indicating a low gene flow between both species. The genetic diversity within the pure M. sylvestris populations was high with a weak genetic structure between the M. sylvestris populations indicating an unrestricted genetic exchange between these M. sylvestris populations. The clear distinguishing of M. sylvestris and M. ×domestica confirms our expectation of the existence of pure M. sylvestris accessions in this area and supports the argument for the implementation of preservation measures to protect the M. sylvestris populations in Saxony.
K E Y W O R D S chloroplast DNA, European wild apple, haplotypes, hybridization, microsatellites, species delimitation
... The genus Malus Mill. (Rosaceae) comprises about 25 to 47 species including one of the most important fruit crops, M. domestica [10]. The species delimitations and phylogenetic relationships among the taxa in the genus are complex in part due to the hybridization events that are prevalent throughout the genus Malus [10,11]. ...
... (Rosaceae) comprises about 25 to 47 species including one of the most important fruit crops, M. domestica [10]. The species delimitations and phylogenetic relationships among the taxa in the genus are complex in part due to the hybridization events that are prevalent throughout the genus Malus [10,11]. Hybridization between the cultivated apples (M. ...
There is growing attention given to gene flow between crops and the wild relatives as global landscapes have been rapidly converted into agricultural farm fields over the past century. Crop-to-wild introgression may advance the extinction risks of rare plants through demographic swamping and/or genetic swamping. Malus sieversii, the progenitor of the apple, is exclusively distributed along the Tien Shan mountains. Habitat fragmentation and hybridization between M. sieversii and the cultivated apples have been proposed to be the causal mechanism of the accelerated extinction risk. We examined the genetic diversity pattern of eleven wild and domesticated apple populations and assessed the gene flow between M. sieversii and the cultivated apples in Ka-zakhstan using thirteen nuclear microsatellite loci. On average, apple populations harbored fairly high within-population diversity, whereas population divergences were very low suggesting likely influence of human-mediated dispersal. Assignment results showed a split pattern between the cultivated and wild apples and frequent admixture among the apple populations. Coupled with the inflated contemporary migration rates, the admixture pattern might be the signature of increased human intervention within the recent past. Our study highlighted the prevalent crop to wild gene flow of apples occurring in Kazakhstan, proposing an accelerated risk of genetic swamping.
... The assumption that M. sieversii and its close relatives were the progenitors of the domesticated apple according to Vavilov (1926) is because they produce similar fruits to the domesticated apple. Molecular analysis later backed up this claim leading to concrete suggestions that M. sieversii is, in fact, the progenitor of the domesticated apple (Robinson et al. 2001;Harris et al. 2002). ...
... (Figure 1.2) used in the research works described in this thesis, is a small deciduous shrub naturally occurring on mesic habitats along the Pacific coast of North America, specifically from the northern part of California to the Kenai Peninsula in Alaska (Viereck and Little 1986;Routson et al. 2012). It falls genetically within the group of species that are native to central Asia based on AFLP analysis (Qian et al. 2006) and nuclear ribosomal and chloroplast DNA (Robinson et al. 2001). The branches bear sharp thorn-like spur-shoots, and areas of older bark have deep fissures. ...
... Malus sieversii (Lebed.) M. Roem, a wild apple tree, has been recognized as the progenitor of the domesticated apple based on morphological (Robinson et al. 2001) and genomic evidence (Coart et al. 2006;Velasco et al. 2010). Malus sieversii is distributed throughout Central Asia, particularly along the Tian Shan mountain ranges (Lawrence et al. 2006). ...
... Notably, M. 3domestica appeared to be the most closely related species to M. sylvestris instead of M. sieversii ( Figure 1). The result is somewhat conflicting with the relationship expected from the morphology as M. 3domestica shared the most morphological similarity with M. sieversii (Robinson et al. 2001). Given the limited data set available in our study, caution must be taken to interpret the inferred phylogeny. ...
We report a complete chloroplast genome sequence of Malus sieversii. The CP genome was 160,223 bp in length with a typical quadripartite structure. Length of large single-copy (LSC) was 88,334 bp, whereas small single-copy (SSC) was 19,179 bp in length. A pair of inverted repeats (IR) were 26,355 bp. In total, 128 genes were found including 83 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The phylogenetic analysis on concatenated data set retrieved from 78 protein-coding genes revealed that M. sieversii was closely related with both M. ×domestica and M. sylvestris.
... The occurrence of a shared 18-bp duplication in the cpDNAs of wild and cultivated apple supports the close relationship between them. A phylogeny based on the internal transcribed spacer (ITS) of nuclear ribosomal DNA shows that M. domestica cluster closely together M. sieversii, including a rare colored form M. sieversii f. niedzwetzkyana (Robinson et al., 2001;Harris et al., 2002). Data from the sequencing and assembly of the apple genome support the formation of the M. domestica gene pool from M. sieversii (Velasco et al., 2010). ...
The present review summarizes the information on the botany, breeding, genetic features, cultivation, and nutraceutical values of red-fleshed apples. Malus sieversii var. niedzwetzkyana or Niedzwetzky’s apple became widely known after the publication of Georg Dieck in the last XIX century. It is characterized by anthocyanin coloration of all organs. Another source of red flesh is the ancient variety ‘Surprise’, which differs from the Niedzwetzky’s apple by a mutation in another gene. These two mutated genes, MYB10 and MYB110a, are located on chromosomes 9 and 17, respectively. Their expression correlated with the anthocyanin accumulation. In type 1 red-fleshed apples, which belong to the Niedzwetzky’s apple progeny, the transcription factor MYB10 confers extensive anthocyanin accumulation in fruit flesh and skin, flowers, leaves, and stems. In type 2 red-fleshed apples, the ‘Surprise’ progeny, only the flesh is red, determined by the transcription factor MYB110а. A new combination Malus domestica f. niedzwetzkyana comb. nov. has been proposed for orchard apples, originated from Niedzwetzky’s apple. The apple cultivars which are progeny of Niedzwetzky’s apple and ‘Surprise’ apple can be placed to Malus Niedzwetzkyana Group and Malus Surprise Group, respectively. All red-fleshed cultivars of orchard apple can be grouped together into Malus domestica Red Flesh Group. Many dozens of new ornamental apple trees have been developed for of European and North American conditions, including the most famous red-flowered centennial apple varieties such ‘Aldenhamensis’, ‘Lemoinei’, ‘Makamik’, and ‘Oekonomierat Echtermeyer’. Rootstocks ‘MB’, ‘PB9’, ‘54-118’, ‘62-396’ and others have become popular in nurseries for the propagation of dwarf and semi-dwarf apple trees thanks to their red leaves, which are useful when removing scion shoots from budded plants. In the F3-F4 and next generation, the new high-quality red-fleshed cultivars have been developed by crossing both Niedzwetzky’s apple and ‘Surprise’ apple with the best orchard apple varieties. Marker-assisted breeding shows great promise for accelerating the development of new red-fleshed cultivars with outstanding traits. The use of the Redlove®, Red Moon®, Kissabel®, and Lucy™ apples brands will ensure the red-fleshed apples’ best path to the consumer as well as the fruit quality and production volume of these novelties. Increasing the consumption of red-fleshed apples is essential for a healthy diet.
... Apple trees (Malus x domestica Borkh.) were known and used as early as 1000 BC (Juniper et al., 1999;Morgan & Richards, 2002;Cornille et al., 2014), and vast apple orchards were planted in ancient Europe and Asia (Cornille et al., 2014). Currently, most specialists believe that the genus Malus comprises 25-30 species and several subspecies (Robinson et al., 2001;Kellerhals, 2009). An apple, a fruit produced by the tree species Malus domestica from the rose family (Rosaceae), is the most important and most widely cultivated fruit in the world (Ferree & Warrington, 2003;Thamaraikannan et al., 2010;Czernyszewicz, 2016). ...
Our study tested the pollination effectiveness of the megachilid bee Osmia bicornis L. (syn. Osmia rufa ) on three apple cultivars (cv.): Lobo, Piros and Champion. The following pollination treatments were compared for each cultivar: insect pollination - caged trees with Osmia bicornis (syn. Osmia rufa ) bees; open pollination - uncaged trees; self-pollination - caged trees without bees. Pollination success was measured based on the percentage of fruit set, the fruit yield per tree (measured as number of fruits and total fruit weight) and the number of seeds per fruit. Generally, there was a higher percentage of initial fruit-set and fruits at harvest on open-pollinated trees than on caged trees without bees, with an intermediate value recorded for caged trees pollinated by O. bicornis (syn. O. rufa ). However, the fruit set on trees pollinated by O. bicornis (syn. O. rufa ) was high and ranged from 49 to 69%, depending on the cultivar. The cv. Lobo trees pollinated by O. bicornis (syn. O. rufa ) and open-pollinated trees produced higher fruit yields than without bees. Furthermore, the number of seeds per fruit was higher. Fruit yield and the number of seeds per fruit were higher for trees pollinated by O. bicornis (syn. O. rufa ) than for caged trees without insects but lower than for open pollination trees of cv. Piros and cv. Lobo.
... Medicinal plants used in this studyTable 2. Sequences of primers used for multiplication of intra or intergenic locations(Asadi et al., 2015;Robinson et al., 2001) ...
DNA barcoding is a straightforward strategy that uses short orthologous genetic sequences and standard genomes to specify species. This technique has the capability of molecular identification, detection of living species and discovery of unfamiliar species, preservation of genetic resources, identification of genetic diversity and phylogenetic characterization, and testing of differentiated existing plant species, as well as assuring the safety and efficacy of pharmaceuticals. In this experiment, the allelic diversity of 7 classes of medicinal plants viz. fenugreek, local fenugreek, waybread, cumin, flax, fixweed and sesame, from Ilam and Khuzestan provinces; west and south of Iran, respectively, was carried out employing this technique and with the aid of primers designed and established on ITS nuclear barcodes (ITS1 and ITS2 genes). The results indicated that there was a great difference between the fragments and the duplicated sequences of ITS1 and ITS2 barcodes in different samples. Moreover, the nucleotide searching of the sequences showed that there was a very high similarity (more than 90%) between the acquired sequences and their equivalents in the NCBI database. The nucleotide sequence of the ITS1 gene of fenugreek showed the highest similarity (78.2%) with native fenugreek. Regarding the ITS1 gene, more amount of G~C content than A~T was observed and, in the waybread plants the amount of C base was higher than G, and for native fenugreek, the amount of A~T content was more than G~C. In the case of ITS2 position, in all examined samples (except the fixweed plant, which had higher A~T), the values of G~C content were higher than A~T. The output of the cluster analysis with the UPGMA algorithm showed the precise grouping and separation of species and the high potential of these sequences using the barcode system in the phylogenetic evaluation of medicinal plant species.
... Resequencing of 33 wild Malus species (including from the sections of Malus, Sorbomalus, Chloromeles, Docyniopsis, and Eriolobus, Robinson et al., 2001) as well as 'Winter Red', 'Radiant' and their hybrid progeny showed that the PGT1 InDel and the two PGT2 SNPs could be used to accurately predict the occurrence of phlorizin and trilobatin in all Malus leaf samples ( Figures S4 and S5). ...
Dihydrochalcones (DHCs) including phlorizin (phloretin 2′‐ O ‐glucoside) and its positional isomer trilobatin (phloretin 4′‐ O ‐glucoside) are the most abundant phenylpropanoids in apple ( Malus spp.). Transcriptional regulation of DHC production is poorly understood despite their importance in insect‐ and pathogen‐plant interactions in human physiology research and in pharmaceuticals. In this study, segregation in hybrid populations and bulked segregant analysis showed that the synthesis of phlorizin and trilobatin in Malus leaves are both single‐gene‐controlled traits. Promoter sequences of PGT1 and PGT2 , two glycosyltransferase genes involved in DHC glycoside synthesis, were shown to discriminate Malus with different DHC glycoside patterns. Differential PGT1 and PGT2 promoter activities determined DHC glycoside accumulation patterns between genotypes. Two transcription factors containing MYB‐like DNA‐binding domains were then shown to control DHC glycoside patterns in different tissues, with PRR2L mainly expressed in leaf, fruit, flower, stem, and seed while MYB8L mainly expressed in stem and root. Further hybridizations between specific genotypes demonstrated an absolute requirement for DHC glycoside production in Malus during seed development which explains why no Malus spp. with a null DHC chemotype have been reported.
... Hybridization has long been attributed to blurred genotypic and phenotypic boundaries in plants (Lotsy, 1925;McVay et al., 2017;Novaković et al., 2022;Robinson et al., 2001;Shaw & Small, 2004), but our study contributes to a growing body of evidence that hybridization is also a source of taxonomic uncertainty in animal clades (Gill, 2014;Pyron et al., 2020). ...
Genomic-scale datasets, sophisticated analytical techniques, and conceptual advances have disproportionately failed to resolve species boundaries in some groups relative to others. To understand the processes that underlie taxonomic intractability, we dissect the speciation history of an Australian lizard clade that arguably represents a "worst-case" scenario for species delimitation within vertebrates: the Ctenotus inornatus species group, a clade beset with decoupled genetic and phenotypic breaks, uncertain geographic ranges, and parallelism in purportedly diagnostic morphological characters. We sampled hundreds of localities to generate a genomic perspective on population divergence, structure, and admixture. Our results revealed rampant paraphyly of nominate taxa in the group, with lineages that are either morphologically cryptic or polytypic. Isolation-by-distance patterns reflect spatially continuous differentiation among certain pairs of putative species, yet genetic and geographic distances are decoupled in other pairs. Comparisons of mitochondrial and nuclear gene trees, tests of nuclear introgression, and historical demographic modelling identified gene flow between divergent candidate species. Levels of admixture are decoupled from phylogenetic relatedness; gene flow is often higher between sympatric species than between parapatric populations of the same species. Such idiosyncratic patterns of introgression contribute to species boundaries that are fuzzy while also varying in fuzziness. Our results suggest that "taxonomic disaster zones" like the C. inornatus species group result from spatial variation in the porosity of species boundaries and the resulting patterns of genetic and phenotypic variation. This study raises questions about the origin and persistence of hybridizing species and highlights the unique insights provided by taxa that have long eluded straightforward taxonomic categorization.
... It is possible that crystals contribute to an increase in the osmotic pressure of the cell sap, which, in turn, increases the absorption capacity of cells. On the other hand, the epidermis, which has crystals in its cells, becomes shiny (the function of the cuticle is to protect and waterproof the plant (Robinson et al., 2001). As a result, thanks to the wax layer, the sun's rays are reflected more, protecting the plants from overheating and therefore At one time, Castanheira et al. (2016) described how, with a lack of water, the genetic variability of apple leaves was higher in terms of anatomical characteristics; Thus, these results can be used to recommend our varieties, which showed leaf plasticity under conditions lack of water. ...
The article describes changes in the structure, leaves, (including mesophyll structure, structure of the midrib, distribution of stomata, and the number of vascular bundles) in Malus during the growing season (from June to August) under the influence of prolonged drought. The leaves anatomy and morphology were investigated by methods of light and scanning electron microscopy. The study was carried out on four representatives of the genus Malus: M. niedzwetzkyana Borkh., M. baccata ‘Pendula’, M. domestica ‘Eliza Rathke’, M. domestica ‘Renet Simirenko’. The influence of drought on the size of the mesophyll of the leaf plate and the number of stomata along the stretch from June to August was studied. The cell circumference of the sclerenchyma ranged from μm in 27.33 (M. niedzwetzkyana) to 81.92 μm (in M. domestica ‘Elise Rathke’). The number of stomata varied from 214.0 units in (M. domestica ‘Renet Simirenko’) to 304.0 units in (M. baccata ‘Pendula’), length from 11.6 μm (M. baccata ‘Pendula’) to 28.63 μm (M. domestica ‘Elise Rathke’), width from 9.4 μm (M. domestica ‘Elise Rathke’) up to 21.8 μm (M. domestica ‘Elise Rathke’) μm. The length of the trichomes varied from 409.92 μm (M. domestica ‘Renet Simirenko’) to 745.09 μm (M. niedzwetzkyana). Also, the anocytic stomatal type, the number, different stomata and trichomes, the presence of wax on the cuticle, and the found druses of calcium oxalate in M. baccata ‘Pendula’, can be important for systematic phylogeny. Thanks to these studies, it is possible to suggest physiological adaptability of apple trees to prolonged drought, as well as to identify more resistant phenotypes for the breeding process to develop resistant cultivars.
... Nevertheless, some limitations were herein experienced, such as measurement overlapping in quantitative descriptors (Reim et al., 2012;Robinson et al., 2001;Wagner, 1996); a lack of levels in qualitative descriptors (Höfer et al., 2014;Reim et al., 2012); a lack of spatial structure (Reim et al., 2012), the uncontrolled effects of the environment on the genotype expression (Höfer et al., 2014) and that the expression of genes from feral apples might difficult the proper identification of those individuals as M. domestica (Kišek et al., 2021). In our case, the lack of spatial structure might be due to the small territory sampled, as genetic studies on M. sylvestris estimate that there are three to five differentiated populations in Europe (Cornille et al., 2013(Cornille et al., , 2015, and the whole Iberian Peninsula is in the Southern one (Cornille et al., 2015). ...
The crab apple tree (Malus sylvestris (L.) Mill.) is a European indigenous species currently listed as endangered due to habitat fragmentation and cross back pollination with the apple tree (M. domestica Borkh.). There are some morphological studies on crab apples, but the state of that species remains unknown in Spain. The aim of this work was to describe morphologically crab apples and feral apples in mountainous areas from central Spain, to select morphological markers which better discriminate between species and to detect possible hybrids. To do so, we phenotyped a total of 355 Malus individuals from the Guadarrama and Ayllón mountain ranges and two wild populations from other Spanish regions through 68 morphological descriptors (8 in 1-year old shoots, 15 in leaves, 16 in flowers and 29 in fruits) from 2016 to 2019. We added 15 cultivated apples from the IMIDRA gene back, both traditional cultivars (9) and international references (6) to anchor our analysis. As a result, we found a high morphological diversity in the sampling area, highlighting that feral apples shown larger diversity than crab apples. In addition, no single descriptor perfectly discriminates between species, as variances in the morphological traits used to overlap. Nevertheless, pubescence, number of petals, fruit size, shape and fruit cavities deserve further research. Gene flux may exist in the area and could be responsible to such overlap, because the 25% of the feral trees and the 21% of crab apple trees shown intermediate shapes.
... The origin of this culture is still disputable, but most morphological and molecular data indicate that Malus sylverstris (Ledeb.) roem from Central Asia is the main maternal ancestor of the cultivated apple (Robinson et al., 2001;Harris et al., 2002). The genetic diversity of M. ...
Two new neophytes, Oenothera fruticosa L. and Phacelia campanularia A. Gray were discovered in the early summer of 2021 during fieldwork in the vicinity of Olovo (Central Bosnia). They are native to North America, but they have been introduced to some areas beyond their natural range. This is the first record of those species for Bosnia and Herzegovina. Brief information on the species distribution in Bosnia and Herzegovina, as well as a discussion of the alien and invasive status in the country are provided. All recently found localities are restricted to road verges and, apparently, reflect a recent human assisted colonization of the species. Judging from the literature and observations in the field both species should be considered casual, non-invasive species in Bosnia and Herzegovina. The text is illustrated with photographs from the new localities of both species.
... The origin of this culture is still disputable, but most morphological and molecular data indicate that Malus sylverstris (Ledeb.) roem from Central Asia is the main maternal ancestor of the cultivated apple (Robinson et al., 2001;Harris et al., 2002). The genetic diversity of M. ...
The research included seven autochthonous apple varieties in the area of Tomislavgrad, Stipanjići locality, during 2018, which represent the natural wealth of our country. In seven autochthonous apple varieties: Petrovača bijela, Budimka, Ljutika-Divljaka, Ledarica, Bedrica, Ljepocvjetka-Cvjetača and Jonatanka, phenological characteristics were monitored and analyzed with morphological-pomological properties of fruits. The following phenological characteristics were monitored: flowering phenophases, germination of the first fruits, fruit growth, fruit ripening and full maturity. Five characteristics for the description of apple fruits were determined using the UPOV descriptor for apples (UPOV, 2003). The results of monitoring the morphological and pomological properties of fruits show that the lowest average fruit weight was in the variety of Cvjetača (58,38 g), while the highest average of fruit weight had variety Bedrica (140,59 g). In the result is evident that the lowest value of fruit width had variety Cvjetača (53,72 mm), and the highest had variety of Jonatanka (70,83 mm). The Cvjetača variety had the lowest average fruit lenght (47,24 mm), while the Bedrica variety had the highest (59,72 mm). The Budimka variety had the highest average stem length (2,73 cm), while the Divljak variety had the lowest average stem length (1,43 cm). The Jonatanka variety had the largest average cup concavity and was (1,28 mm), while the Petrovača bijela variety (0,41 mm) had the lowest average cup concavity. Based on the this research, the examined autochthonous apple varieties can be used a valuable genetic material in breeding programs, and can be used to create new varieties, as well as for propagation in commercial plantations.
... The origin of this culture is still disputable, but most morphological and molecular data indicate that Malus sylverstris (Ledeb.) roem from Central Asia is the main maternal ancestor of the cultivated apple (Robinson et al., 2001;Harris et al., 2002). The genetic diversity of M. ...
Cilj ovog rada je da se kroz prikaz rezultata kemijskih i senzorskih analiza provedenih u okviru manifestacije "Dani mladog maslinovog ulja u Dalmaciji" prikaže kvaliteta djevičanskog maslinovog ulja sorte Oblica proizvedeno godine 2021. S obzirom na lokalitete pristiglih uzoraka ulja može se govoriti o uljima sorte Oblica iz dalmatinskog uzgojnog područja. Kemijskom analizom određeni su osnovni kemijski pokazatelji kvalitete: peroksidni broj (PB) izražen u mEq O2 / kg i udio slobodnih masnih kiselina (SMK) u % izraženih kao oleinska kiselina. Senzorska analiza provedena je od strane udruge "Olea" iz Šibenika. Rezultati kemijske i senzorske analize za svaki pojedini uzorak numerički su izraženi kao jedinstvena ocjena koja je rangirala sve pristigle uzorke i izdvojila najbolja maslinova ulja. Ukupni bodovi za ekstra djevičansko maslinovo ulje sorte Oblica iznosili su od 72,35 do 96,45 i obuhvatili su 84 % od ukupno zaprimljenih uzoraka ulja. Dobiveni rezultati ulja pokazuju da se radi o ekstra djevičanskim i djevičanskim maslinovim uljima visoke kvalitete, što upućuje na činjenicu da su ulja dobivena od optimalno zrelih i zdravih plodova te da je prerada obavljena vrlo brzo nakon berbe. Senzorsko ocjenjivanje uzoraka imalo je iznimno važan utjecaj na konačni plasman ulja.
... It was noted that the wild apple has significant ecological and biological functions, and due to its high fruit polymorphism, it serves as a vital source for plant breeding. Phylogenetic studies showed that M. sieversii is the ancestor of the cultivated apple tree and has a valuable gene pool for apple plant breeders (Zhou, Li, 2000;Robinson et al., 2001;Forsline et al., 2003;Juniper, Mabberley, 2006). Malus sieversii was listed in the Red Book (Dzhangaliev et al., 1981;Isayev, 2014) and was registered in the International Red List in 2000 as vulnerable (VU) (IUCN, 2000). ...
... Among the Rosaceae cluster, P. avium, which belongs to Amygdaleae subfamily, was distinct from the other 7 species of Maleae subfamily, which also supports the classification of Amygdaleae and Maleae subfamily 57,58 . Meanwhile, these species in the same genus were clustered together, such as S. aucuparia and S. torminalis, M. hupehensis and M. domestica, which is consistent with previous reports based on morphological and genetic data [57][58][59] . ...
Plant mitochondrial genomes (mitogenomes) are a valuable source of genetic information for a better understanding of phylogenetic relationships. However, no mitogenome of any species in the genus of Photinia has been reported. In this study, using NGS sequencing, we reported the mitogenome assembly and annotation of Photinia serratifolia, which is 473,579 bp in length, contains 38 protein-coding genes, 23 tRNAs, and 6 rRNAs, with 61 genes have no introns. The rps2 and rps11 genes are missing in the P. serratifolia mitogenome. Although there are more editing sites (488) in the P. serratifolia mitogenome than in most angiosperms, fewer editing types were found in the P. serratifolia mitogenome, showing a clear bias in RNA-editing. Phylogenetic analysis based on the mitogenomes of P. serratifolia and 8 other taxa of the Rosaceae family reflected the exact evolutionary and taxonomic status of P. serratifolia. However, Ka/Ks analysis revealed that 72.69% of the protein-coding genes in the P. serratifolia mitogenome had undergone negative selections, reflecting the importance of those genes in the P. serratifolia mitogenome. Collectively, these results will provide valuable information for the evolution of P. serratifolia and provide insight into the evolutionary relationships within Photinia and the Rosaceae family.
... Presently, M. sieversii (Ledeb.) (Robinson et al., 2001) is ubiquitous in Central Asia's highlands of advancements among 1200 m and 1800 m. ...
... Presently, M. sieversii (Ledeb.) (Robinson et al., 2001) is ubiquitous in Central Asia's highlands of advancements among 1200 m and 1800 m. ...
... It is mainly pollinated by bees and flies, and thanks to its small and hard fruits, the trees are often called crab apples. This species occurs across Western and Central Europe, from southern Scandinavia to the Iberian Peninsula and from the Volga to the British Isles [1]. With a high up to 10 m, it grows in low-density populations and the growth habit looks like shrubs, more than trees. ...
The European wild apple (Malus sylvestris L.), a wild contributor to the domesticated apple, belongs to the endangered species in the Czech Republic. Thus, an efficient protocol was developed for in vitro plantlet regeneration using the post-dormant buds. The highest shoot induction was obtained on MS medium supplemented with 0.5 mg.l−1 BAP, 5 mg.l−1 GA and 0.1 mg.l−1 IBA. Shoot multiplication and elongation took place on the same medium with 0.2 mg.l−1 BAP and 0.1 mg.l−1 IBA. Indole-3-butyric acid at 0.5 mg.l−1 was most effective for rooting. The micropropagated plantlets were successfully acclimatized in greenhouse conditions and were transplanted into soil in forest. Finally, qualitative and quantitative parameters of tissue culture-derived plants were evaluated. Monitoring of in vitro plantings on experimental trials suggests that micropropagated wild apple trees retain the growth characteristics of generative individuals.
... M. sieversii germplasm accessioned into the NPGS has been distributed as budwood of accessions resulting from imported budwood of wild trees considered "elites", budwood of accessions grown from wild-collected seeds, and seed from crossing among wild accessions grown ex situ. These materials have subsequently been used to determine genetic relationships between M. domestica cultivars and M. sieversii (Robinson et al., 2001;Gharghani et al., 2009;Nikiforova et al., 2013;Duan et al., 2017;Wedger et al., 2021), to evaluate phenotypic diversity of traits (Janisiewicz et al., 2008;Fazio et al., 2009;Bassett et al., 2011;Jurick et al., 2011;Van Nocker et al., 2012;Fazio et al., 2014;Maguylo and Bassett, 2014;Harshman et al., 2017;Watts et al., 2021;Davies et al., 2022), and to identify QTLs and novel alleles (Xu et al., 2012;Wisniewski et al., 2020;Singh et al., 2021). ...
The USDA-ARS National Plant Germplasm System (NPGS) apple collection in Geneva, NY, USA maintains accessions of the primary Malus domestica (Suckow) Borkh. progenitor species M. sieversii (Ledeb.) M. Roem., M. orientalis Uglitzk., and M. sylvestris (L.) Mill. Many of these accessions originated from seeds that were collected from wild populations in the species’ centers of diversity. Some of these accessions have fruit phenotypes that suggest recent M. domestica hybridization, which if true would represent crop contamination of wild species populations and mislabeled species status of NPGS accessions. Pedigree connections and admixture between M. domestica and its progenitor species can be readily identified with apple SNP array data, despite such arrays not being designed for these purposes. To investigate species purity, most (463 accessions) of the NPGS accessions labeled as these three progenitor species were genotyped using the 20K apple SNP array. DNA profiles obtained were compared with a dataset of more than 5000 unique M. domestica apple cultivars. Only 212 accessions (151 M. sieversii, 26 M. orientalis, and 35 M. sylvestris) were identified as “pure” species representatives because their DNA profiles did not exhibit genotypic signatures of recent hybridization with M. domestica. Twenty-one accessions (17 M. sieversii, 1 M. orientalis, and 3 M. sylvestris) previously labeled as wild species were instead fully M. domestica. Previously unrealized hybridization and admixture between wild species and M. domestica was identified in 230 accessions (215 M. sieversii, 9 M. orientalis, and 6 M. sylvestris). Among these species-mislabeled accessions, ‘Alexander’, ‘Gold Reinette’, ‘Charlamoff’, ‘Rosmarina Bianca’, and ‘King of the Pippins’ were the most frequently detected M. domestica parents or grandparents. These results have implications for collection management, including germplasm distribution, and might affect conclusions of previous research focused on these three progenitor species in the NPGS apple collection. Specifically, accessions received from the NPGS for breeding and genomics, genetics, and evolutionary biology research might not be truly representative of their previously assigned species.
... Additionally, the analyses conducted in this study indicated that C7 shares a similar genetic profile with M. baccata (Figs. 4 and 5; Tables 2 and 3). However, previous studies have reported inconsistencies in the identification/characterization of M. mandshurica, with some studies reporting a close relationship between M. mandshurica and M. baccata or M. micromalus 28,29,31,37 . Physiologically, studies have reported that the leaves of plants become smaller and thicker, and the amount of hair increases as the altitude increases 101,102 ; thus, further studies are needed to analyze the status of M. mandshurica at the species level. ...
This study was to understand the genetic structure and diversity of the Korean Malus species. We used genotyping-by-sequencing (GBS) technology to analyze samples of 112 individuals belonging to 18 populations of wild Malus spp. Using GBS, we identified thousands of single nucleotide polymorphisms in the species analyzed. M. baccata and M. toringo, two dominant mainland species of the Korean Peninsula, were distinguishable based on their genetic structure. However, M. toringo collected from Jeju Island exhibited a different genetic profile than that from the mainland. We identified M. cf. micromalus as a hybrid resulting from the Jeju Island M. toringo (pollen donor) and the mainland M. baccata, (pollen recipient). Putative M. mandshurica distributed on the Korean Peninsula showed a high structural and genetic similarity with M. baccata, indicating that it might be an ecotype. Overall, this study contributes to the understanding of the population history and genetic structure of Malus in the Korean Peninsula.
... Presently, M. sieversii (Ledeb.) (Robinson et al., 2001) is ubiquitous in Central Asia's highlands of advancements among 1200 m and 1800 m. ...
Owing to polymorphism, apple has extraordinary diversity. Depending on varieties, apple fruits can differ in colors and shades, and size. There are more than 10000 varieties of apple, which vary in taste, shape, juiciness, texture, color, firmness and other qualities. For this reason, apple has been diversely studied from time to time and many improvements have been made like that of introduction of high density cropping; rootstock breeding; or varietal development etc. Therefore it is important to understand and document the production ways and methods implemented over times for harvesting the maximum possible benefits of the crop. Apples: Preharvest & Postharvest Technology has documented all the production practice that are taken in practice with detailed illustration on varieties, rootstocks, important cultural practices and post harvest management. This book will therefore serve as a complete guide for apple production from farm to fork and will help students, scholars, researchers and scientists working in this domain. The book will benefit pomologists, horticulturalist, agricultural Scientists, food technologists, university scholars, researchers and college students.
... In fact, some authors attribute to it only 8 species [155], others from 25 to 47 species, depending on the rank assigned to different taxa and on the acceptance of putative hybrids [156], up to 78 species [157]. The differences in classification are mainly due to the taxonomic level at which infrageneric groupings of species are recognized, although there is broad agreement on the species that comprise these groupings [158]. ...
An updated overview of the 29 threatened crop wild relatives (CWRs) endemic to Italy is presented, namely: Arrhenatherum elatius subsp. nebrodense, Barbarea rupicola, Brassica baldensis, Brassica glabrescens, Brassica macrocarpa, Brassica rupestris subsp. hispida, Brassica rupestris subsp. rupestris, Brassica tardarae, Brassicatrichocarpa, Brassica tyrrhena, Brassica villosa subsp. bivonana, Brassica villosa subsp. brevisiliqua, Brassica villosa subsp. drepanensis, Brassica villosa subsp. tineoi, Brassica villosa subsp. villosa, Daucus broteroi, Daucus carota subsp. rupestris, Daucus nebrodensis, Diplotaxis scaposa, Festuca centroapenninica, Lathyrus apenninus, Lathyrus odoratus, Malus crescimannoi, Phalaris arundinacea subsp. rotgesii, Vicia brulloi, Vicia consentina, Vicia giacominiana, Vicia ochroleuca subsp. ochroleuca, Vicia tenuifolia subsp. elegans. Data concerning geographical distribution, ecology (including plant communities and habitats of the Directive 92/43/EEC), genetics (chromosome number, breeding system, and/or the existence of gene pools), threat status at the national and international level (Red Lists), key plant properties, and in situ and ex situ conservation were analyzed and shown. At present, most of the listed endemic CWRs, 23 out of 29, have no gene pool at all, so they are CWRs only according to the taxon group and not according to the gene pool concept. In addition, there is a serious lack of data on the ex situ conservation in gene banks, with 16 species identified as high priority (HP) while 22 taxa have high priority (A) for in situ conservation. With the aim of their protection, conservation, and valorization, specific and urgent actions are recommended.
... Le pommier domestique ou Malus domestica est issu du croisement entre plusieurs espèces de Malus d'après des analyses de diversité réalisées à partir de données historiques, morphologiques et génétiques (Harris et al., 2002;Juniper and Mabberley, 2006;Velasco et al., 2010;Cornille et al., 2012). L'origine de cette espèce proviendrait de l'espèce Malus sieversii en Asie centrale (Robinson et al., 2001;Forte et al., 2002;Harris et al., 2002;Juniper and Mabberley, 2006;Velasco et al., 2010). La propagation et la commercialisation de cette culture le long de la Route de la soie depuis la Chine jusqu'à l'Europe de l'ouest (Figure 2 ; Juniper and Mabberley, 2006) aurait contribué à la diversification de l'espèce Malus sieversii. ...
Diversifier les méthodes de protection des cultures est un enjeu majeur pour réduire l’utilisation de pesticides. Le déploiement de variétés génétiquement résistantes et les stimulateurs de défense des plantes(SDP) sont deux méthodes de protection alternatives prometteuses mais qui peuvent être individuellement rapidement contournées ou d’efficacité partielle et variable. L’utilisation combinée de ces deux types de résistances a été envisagée pour s’affranchir de ces limites et développer une stratégie intégrée de protection durable du pommier.Le pommier est l’une des cultures les plus traitées, du fait de variétés commerciales majoritairement sensibles aux bioagresseurs. Cette étude a visé deux maladies majeures : la tavelure (Venturia inaequalis) et le feu bactérien (Erwinia amylovora). Une descendance F1 dans laquelle ségrègent des QTLs de résistance, ainsi qu’une collection de variétés anciennes ont été utilisées. Quatre produits SDP ont été testés mais plus particulièrement l’Acibenzolar-S-Methyl, un analogue de l’acide salicylique.La complémentarité des résistances génétiques et induites a été explorée par des approches phénotypiques et génétiques afin de comprendre la nature de l’interaction entre ces résistances et les facteurs pouvant l’influencer.En complément, les mécanismes moléculaires impliqués dans ces résistances ont été explorés par des approches transcriptionnelles et de métabolomique.La combinaison de ces résistances s’avère être complémentaire et très efficace pour la protection des pommiers mais ne fait pas intervenir de modulation forte de l’effet des QTLs de résistance. La signalisation par les acides salicyliques et jasmoniques, les flavonoïdes et les acides gras semblent jouer un rôle dans ces résistances.Les résultats obtenus ouvrent des premières pistes pour l’élaboration de modèles conceptuels et mécanistiques de l’interaction entre les résistances génétiques et induites par les SDP.
... Koidz., which is distributed in Central Asia (Janick et al., 1996;Velasco et al., 2010;Cornille et al., 2012). A contribution of M. baccata Loisel., M. orientalis Uglitzk, ex Juz. and also M. sylvestris has also been proven (Wagner & Weeden, 2000;Robinson et al., 2001;Harris et al., 2002;Harrison & Harrison, 2011;Cornille et al., 2012). The proportion of M. sylvestris genes differs greatly depending on the cultivar of the domesticated apple, however (cf. ...
... Koidz., which is distributed in Central Asia (Janick et al., 1996;Velasco et al., 2010;Cornille et al., 2012). A contribution of M. baccata Loisel., M. orientalis Uglitzk, ex Juz. and also M. sylvestris has also been proven (Wagner & Weeden, 2000;Robinson et al., 2001;Harris et al., 2002;Harrison & Harrison, 2011;Cornille et al., 2012). The proportion of M. sylvestris genes differs greatly depending on the cultivar of the domesticated apple, however (cf. ...
Question
Malus sylvestris is considered an endangered tree species in Central Europe. Hybridization with Malus domestica poses a serious threat to the genetic integrity of the wild species. Here we investigate whether M. sylvestris and the hybrid M. domestica × sylvestris occur in the same habitat or have different ecological niches and whether M. sylvestris is threatened by displacement by the hybrid.
Location
Northern Bavaria
Methods
Taxon delimitation using six genetic microsatellite markers and 613 Germany-wide references of M. sylvestris and 75 cultivars. To determine differences in the ecological niches between M. sylvestris and hybrids, light availability for the trees was estimated via gap fractions in hemispherical photographs. Soil particle size fractions and pH values were determined for every horizon. Vegetation relevé data was collected, and mean Ellenberg indicator values were calculated. For habitat differences, means in combination with frequency patterns of the parameters were compared, logistic models and Detrended correspondence analysis (DCA) of community data were calculated.
Results
Genetic markers identified 22 M. sylvestris and 11 hybrids, meaning that in the study area the wild taxon is much more frequent than the hybrid. Ecological site differences between the M. sylvestris and its hybrid with M. domestica were best explained by light availability, pH and mean Ellenberg moisture value. In contrast to the ecological demand of the hybrid, Malus sylvestris tolerated wet soil and flooding and even somewhat shadier conditions in the later successional stages. DCA revealed that differences in the composition of plant communities of the taxa were primarily driven by soil moisture.
Conclusions
Our data suggested different ecological niches, which are appropriate to reduce the risk of replacement of M. sylvestris by the hybrid M. domestica x sylvestris. Hence, these findings provide important implications for a more targeted planning of in-situ-conservation strategies of M. sylvestris genomes with low levels of admixture and help to protect plant communities suitable for the threatened wild apple.
... The genus Malus belongs to the family Rosaceae and comprises 30 species of deciduous trees and shrubs native to the temperate regions of the northern hemisphere. Given the diversity of the Malus genus in the wild and cultivation (Robinson et al., 2001;Rohrer et al., 1994), it is unsurprising that its evolutionary origins are controversial. The current mainstream view is that the genus originated in the so-called Chuan-Dian Palaeoland, corresponding to Southern China, Northern Vietnam, and Northern Laos. ...
The evolutionary history of the Malus genus has not been well studied. In the current study, we presented genetic evidence on the origin of the Malus genus based on genome sequencing of 297 Malus accessions, revealing genetic relationship between wild species and cultivated apples. Our results demonstrated that North American and East Asian wild species are closer to the outgroup (pear) than Central Asian species, and Hybrid species including natural (separated before the Pleistocene, about 2.5 Mya) and artificial hybrids (including ornamental trees and rootstocks) are between East and Central Asian wild species. Introgressions from M. sylvestris in cultivated apples appeared to be more extensive than those from M. sieversii, whose genetic background flowed westward across Eurasia and eastward to wild species including M. prunifolia, M. × asiatica, M. × micromalus, and M × robust. Our results suggested that the loss of ancestral gene flow from M. sieversii in cultivated apples accompanied the movement of European traders around the world since the Age of Discovery. Natural SNP variations showed that cultivated apples had higher nucleotide diversity than wild species, and more unique SNPs than other apple groups. An apple ERECTA‐like gene that underwent selection during domestication on 15th chromosome was identified as a likely major determinant of fruit length and diameter, and an NB‐ARC domain‐containing gene was found to strongly affect anthocyanin accumulation using a genome‐wide association approach. Our results provide new insights into the origin and domestication of apples, and will be useful in new breeding programs and efforts to increase fruit crop productivity.
... Three loci were chosen for sequencing based on the availability of sequences from Limosella and Ranunculus in public sequence repositories and their ability to resolve interspecific relationships in these groups (Ito et al. 2017, Lehnebach et al. 2017). The nuclear ribosomal internal transcribed spacer (ITS) region was amplified using the primers AB101 and AB102 (Robinson et al. 2001). The plastid trnL-trnF intergenic region and rps16 intron were amplified with the primers c and f (Taberlet et al. 1991) or rpsF and rpsR2 (Oxelman et al. 1997), respectively. ...
DNA sequence data have become a crucial tool in assessing the relationship between morphological variation and genetic and taxonomic groups, including in the Antarctic biota. Morphologically distinct populations of submersed aquatic vascular plants were observed on sub-Antarctic Marion Island, potentially representing the two species of such plants listed in the island's flora, Limosella australis R.Br. (Scrophulariaceae) and Ranunculus moseleyi Hook.f. (Ranunculaceae). To confirm their taxonomic identity, we sequenced a nuclear locus (internal transcribed spacer; ITS) and two plastid loci ( trnL-trnF , rps 16) from three specimens collected on Marion Island and compared the sequences with those in public sequence databases. For all three loci, sequences from the Marion Island specimens were nearly identical despite morphological dissimilarity, and phylogenetic analyses resolved them to a position in Limosella . In phylogenetic trees and comparisons of species-specific sequence polymorphisms, the Marion Island specimens were closest to a clade comprising Limosella aquatica L., L. curdieana F.Muell. and L. major Diels for ITS and closest to L . australis for the plastid loci. Cytonuclear discordance suggests a history of hybridization or introgression, which may have consequences for morphological variability and ecological adaptation.
... Apple (Malus ssp.), one of the most commonly cultivated fruit crops, supports many local economies in temperate zones. Malus is extremely rich in diversity, with 25 to 78 species in the genus depending on the taxonomic classifications [51,56]. High levels of interspecific hybridization occur naturally, which generates genetic admixtures, contributing to the diversity within the genus [6,7,12]. ...
Background
Apple (Malus ssp.), one of the most important temperate fruit crops, has a long cultivation history and is economically important. To identify the genetic relationships among the apple germplasm accessions, whole-genome structural variants identified between M. domestica cultivars ‘Jonathan’ and ‘Golden Delicious’ were used.
Results
A total of 25,924 insertions and deletions (InDels) were obtained, from which 102 InDel markers were developed. Using the InDel markers, we found that 942 (75.3%) of the 1251 Malus accessions from 35 species exhibited a unique identity signature due to their distinct genotype combinations. The 102 InDel markers could distinguish 16.7–71.4% of the 331 bud sports derived from ‘Fuji’, ‘Red Delicious’, ‘Gala’, ‘Golden Delicious’, and other cultivars. Five distinct genetic patterns were found in 1002 diploid accessions based on 78 bi-allele InDel markers. Genetic structure analysis indicated that M. domestica showed higher genetic diversity than the other species. Malus underwent a relatively high level of wild-to-crop or crop-to-wild gene flow. M. sieversii was closely related to both M. domestica and cultivated Chinese cultivars.
Conclusions
The identity signatures of Malus accessions can be used to determine distinctness, uniformity, and stability. The results of this study may also provide better insight into the genetic relationships among Malus species.
... The genus Malus Mill belonging to the Rosaceae family of plants, is subdivided into six sections including between 25 to 47 species, depending on the taxonomic classification (Robinson et al. 2001, Forsline et al. 2003, GRIN, https://npgsweb.ars-grin.gov). The domesticated apple (Malus ×domestica Borkh.), a prominent member of this genus, is one of the most important fruit crops cultivated in the temperate zone (Hanke et al. 2020). ...
Diplocarpon coronariae causes apple blotch, which results in significant economic losses. Resistance to apple blotch in commercial apple culti-vars has not been reported in recent literature. The Malus germplasm collection from the Fruit Genebank of the Julius Kühn-Institut that is maintained in Dres-den, Germany consists of 516 accessions of about 49 Malus species. This apple gene pool was evaluated for resistance to Diplocarpon coronariae. A four-year field survey was subsequently followed by artificial inoculation of field-selected accessions. Fifteen accessions that represent nine different species and hybrids were confirmed to be highly resistant following a repeated inoculation assay in the laboratory. The results from this investigation is of high interest to breeders for future apple breeding programmes and investigations of resistance to Diplocarpon coronariae.
... Malus domestica is a small deciduous tree (3 to 12 meters) belonging to the Rosaceae family [4]. It is widely distributed in the temperate zone throughout the world [5]. Traditionally, the infusion of the dried flower and leaves is used to control the blood pressure, fruit vinegar is given to the hearing impaired patient, and the fruit is used as diuretics, antidiarrheal, and soft laxative. ...
Malus domestica (Apple) is one of the most widely cultivated cash crops of Nepal. Jumla and Mustang are two major pocket areas for the production of apple. Flavonoids including quercetin and rutin are potent antioxidants present in apples. is study was designed to quantify and compare the presence of quercetin and rutin in different plant parts (peel, leaf, and bark) among various cultivars of Malus domestica from two pocket zones of Nepal. A new HPLC-UV method was developed and validated for the quantification of quercetin and rutin. Polyphenols, flavonoids, and carbohydrate contents were determined by colorimetric methods. 2,2′-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was carried out to measure in vitro antioxidative activity. Acid hydrolysis of each extract was carried out by the standard method to measure aglycone quercetin content after hydrolysis of its glycosides. e total rutin content ranged from 3.69 ± 1.34 to 374.50 ± 2.35 mg/100g dry extract weight. Before the acidic hydrolysis, the total quercetin content ranged from 2.96 ± 0.13 to 171.05 ± 0.95 mg/100g dry extract weight whereas its amount increased highly after the hydrolysis and it ranged from 80.84 ± 19.65 to 7445.32 ± 29.25 mg/100g dry extract weight. Total polyphenol content ranged from 19.48 ± 0.23 to 123.48 ± 1.84 µg gallic acid equivalent/ mg of dry extract weight. Similarly, flavonoid content ranged from 2.21 ± 0.72 µg to 755.54 ± 1.91 µg quercetin equivalent/mg of dry extract weight. Total carbohydrate content ranged from 144.15 ± 3.73 to 484.65 ± 2.63 µg glucose equivalent per 0.5 mg dry extract weight. All the extracts showed the various degrees of antioxidant activity in a dose-dependent manner. Among them, stem bark of the Jonathan Jumla showed potent antioxidant activity with IC 50 value of 13.003 µg/mL. e present study provides the information about variation of the phytochemical content among the different cultivars, parts, and geographic locations. Furthermore, it revealed that bark of Malus domestica cultivars had high quercetin and rutin content with high antioxidant activity.
... The pacific crabapple, M. fusca, is a small deciduous tree that naturally occurs on mesic habitats along the pacific coast of North America, specifically from the northern part of California to the Kenai Peninsula in Alaska (Viereck and Little 1986). It falls genetically within the group of species that are native to central Asia based on AFLP analyses (Qian et al. 2006) and nuclear ribosomal and chloroplast DNA (Robinson et al. 2001). Fire blight resistance of M. fusca was explored by artificially inoculating shoots of five accessions present at the gene bank resource of the Institute for Breeding Research on Fruit Crops, Dresden-Pillnitz. ...
The identification and use of fire blight resistance genes in breeding programmes worldwide is thought to be the most eco-friendly means of tackling the threat posed by the very devastating and erratic fire blight disease of apples, especially as most commercial cultivars are highly susceptible to the causal bacterium – Erwinia amylovora; and the use of antibiotics treatment being forbidden in Germany. The crabapple, Malus fusca, had been found to be highly resistant to fire blight with a strong resistance quantitative trait loci (QTL) mapped on chromosome 10 (Mfu10). Recently, a putative candidate gene underlying Mfu10 was proposed. The candidate gene called FB_Mfu10 was identified on the sequence of a resistant BAC clone, 46H22, spanning the M. fusca fire blight resistance locus. FB_Mfu10 was predicted to possess eight exons and 880 amino acids that encode receptor-like kinase proteins including a bulb-type mannose-specific binding (B-lectin) domain, a catalytic domain of the serine/threonine kinases and interleukin-1 receptor-associated kinases (STKc_IRAK), and the PAN/apple-like domain. These domains are similar to domains of genes that confer resistance to fungal and bacterial disease in other plant species. Furthermore, the amplification of the open reading frame (ORF) on resistance and susceptible clones and the subsequent sequencing of amplicons led to the discovery of eight base pair difference in the first exon that leads to a 28 amino acid difference between resistant and susceptible genotypes and clones.
Therefore, the key objective of the proposed study is to validate the function of FB_Mfu10 in complementing studies. This research is especially necessary as the only functionally proven fire blight gene in Malus, FB_MR5 from M. ×robusta5, is broken down by highly virulent and mutant strains of E. amylovora.
... Its flower pedicels are slender and drooping, the flowers are brightly colored, and many flowers are clustered in umbrellashaped inflorescences; therefore, this species has high ornamental value as a famous horticultural resource (Sun et al. 2011;Yin et al. 2017). However, the taxonomy and relationships of the genus Malus are complex, and the systematic position of many species is unclear, including M. halliana (Robinson et al. 2001). Therefore, we reported the complete chloroplast genome (cp) of M. halliana based on Illumina pair-end sequencing data, probed its systematic position in Malus. ...
Malus halliana is an important ornamental plant resource. Herein, we determined the complete chloroplast (cp) genome sequence of M. halliana using Illumina sequencing data. The whole cp genome is 160,089 bp in size, consisting of a pair of inverted repeats (IR 52,706 bp), a large single-copy region (LSC 88,189 bp), and a small single-copy region (SSC 19,194 bp). The plastid genome contains 129 genes, 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. In addition, a maximum-likelihood phylogenetic analysis demonstrated that M. halliana was most closely related to Malus hupehensis. The complete plastome sequence will provide useful genetic information for phylogenetic studies, the resolution of taxonomic discrepancies, and molecular breeding.
... It was noted that the wild apple has significant ecological and biological functions, and due to its high fruit polymorphism, it serves as a vital source for plant breeding. Phylogenetic studies showed that M. sieversii is the ancestor of the cultivated apple tree and has a valuable gene pool for apple plant breeders (Zhou, Li, 2000;Robinson et al., 2001;Forsline et al., 2003;Juniper, Mabberley, 2006). Malus sieversii was listed in the Red Book (Dzhangaliev et al., 1981;Isayev, 2014) and was registered in the International Red List in 2000 as vulnerable (VU) (IUCN, 2000). ...
Keywords: Clone-varieties of Sievers apple tree, ISSR-PCR, ITS, Malus sieversii, rps16 intron, trnL intron, trnL-trnF spacer. Summary. Malus sieversii (Ledeb.) M. Roem. is recognized as the ancestor of the cultivated apple tree. It has a valuable gene pool, and in the last decades, it becomes endangered in Kazakhstan. The genetic diversity of 13 clone-varieties of Sievers apple tree (Malus sieversii) of Dzungarian population from the introduction collection of the Main Botanical Garden in Almaty (Kazakhstan) and 31 samples from three natural populations were assessed using eight polymorphic ISSR markers. The phylogenetic relationship of the clone-varieties with the natural population was estimated using ribosomal (ITS) and chloroplast DNA (rps16 intron, trnL intron, trn L-trn F). The data revealed a high genetic diversity of various clones and samples of Sievers apple tree of the Dzungarian populations. As a result of phy-logenetic and cluster analysis the studied clones and samples of M. sieversii from natural populations formed a cluster, samples of supposedly hybrid origin formed 2 clusters, and no clustering was detected depending on geographical distance. The data demonstrate that there is an active information exchange between the populations. Ключевые слова: генетическое разнообразие, рибосомальная и хлоропластная ДНК, сорт-клоны яблони Сиверса, ISSR-PCR, ITS, Malus sieversii, rps16 intron, trnL intron, trnL-trnF spacer. 188 Shadmanova L. et al. Molecular-genetic analysis of Malus sieversii Аннотация. Malus sieversii (Ledeb.) M. Roem. (яблоня Сиверса), признанная основным родоначальником культурной яблони и обладающая ценным генофондом, в последние десятилетия находится под угрозой ис-чезновения в Казахстане. Генетическое разнообразие 13 сортов-клонов яблони Сиверса джунгарской популя-ции из интродукционной коллекции Главного ботанического сада г. Алматы (Казахстан) и 31 образец из трех популяций Джунгарского Алатау были изучены с использованием 8 полиморфных межмикросаттеллитных маркеров (ISSR); филогенетическая связь сортов-клонов с природной популяцией оценивалась с помощью ри-босомальной (ITS) и хлоропластной ДНК (rps16 intron, trnL intron and trnL-trnF spacer). В ходе работы выявле-но высокое генетическое разнообразие как сорт-клонов, так и образцов M. sieversii, отобранных из природных популяций в горах Джунгарского Алатау. В результате филогенетического и кластерного анализов изученные сорт-клоны и образцы M. sieversii из природных популяций образовали 1 кластер, образцы предположительно гибридного происхождения образовали 2 кластер, при этом не выявлено какой-либо кластеризации в зависи-мости от географического положения. Данные показывают, что между популяциями идет активный генетиче-ский обмен.
Malus species is important not only from the point of economics but also from a
cultural and nutritional point of view. Most of the Malus species are adapted to the
temperate climatic condition, and there is a growing concern about genetic
erosion due to changing climate conditions and increased efforts for the conservation
of Malus genetic resources. Conservation using complementary conservation
strategy needs to be strengthened along with their increased use through
improved access to users for crop improvement programs. This book chapter
summarizes the origin and distribution, the taxonomic position of apple species,
gene bank collections, conservation methods both in situ and ex situ, targeted
traits and their source, and utilization of the germplasm in breeding programs and
major cultivars developed.
Apple ( Malus × domestica Borkh.) production faces many challenges stemming from abiotic and biotic stresses. Abiotic stressors, such as extreme temperatures, droughts, and spring frosts, can lead to diminished yields and tree loss, while biotic stresses like fire blight and pest infestations further reduce tree health and fruit quality. To lessen the threat of these challenges, plant breeders aim to introduce resistance and resilience genes into cultivated varieties. However, high-relatedness among cultivated varieties and breeding lines, coupled with the long juvenility and generation times in apples, hinder the breeding process. The introduction of resistance traits from wild relatives is also constrained by these factors, as well as the lack of genomic resources that could assist in accelerating the introgression process. Herein, we report the assembly and annotation of Malus angustifolia , the Southern Crabapple, one of Eastern North America's native species. Using a combination of Pacific Biosciences High Fidelity reads, Next-generation short read sequencing, as well as chromatin conformation capture sequencing, we achieve an extremely contiguous haplotype-resolved assembly. We perform comparative haplotypic analyses to identify SNPs and large structural variants, shedding light on the genomic landscape of M. angustifolia . Finally, we explore the phylogenetic and syntenic relationships between Eurasian Malus progenitors and the recently sequenced North American species, contributing valuable insights to the broader understanding of apple evolution and potential breeding strategies.
Velvet longhorned beetle Trichoferus campestris (Faldermann) (Coleoptera: Cerambycidae) is native to Asia. It is reported to be polyphagous in its native range, but hosts have not been screened in its introduced range in the United States. We conducted choice and no‐choice host experiments. For choice assays, gravid T. campestris oviposited freely on cut branches of four tree species: Juglans nigra, Malus domestica, Acer saccharum, and Pinus strobus. We investigated oviposition between apple branches with and without cankers. Half of the choice trials underwent winter temperatures. For no‐choice assays, eggs were placed on cut branches of these same four species. Half of these branches were later dissected to measure larval development. The rest were exposed to winter temperatures and T. campestris emergence was quantified. Overall, Trichoferus campestris oviposition and development occur more readily on J. nigra and M. domestica than on A. saccharum or P. strobus. The insect oviposited more on cankered than uncankered apple wood. Cold exposure during an overwintering period benefitted insect development in adults. The insect's high degree of polyphagy and ability to reproduce in dry wood has likely facilitated its establishment in multiple locales around the world.
Considerăm că cei care au curajul de a pune sub semnul întrebării legi sau fenomene considerate înrădăcinate sau de neschimbat, aceia vor aduce o adevărată contribuție la dezvoltarea societății prin cunoaștere. Curiozitatea, pasiunea pentru citit – inclusiv lucrări din alte domenii ale științei – gândirea critică, creativitatea și spiritul analitic se adaugă listei cu abilități esențiale pentru un viitor cercetător. Cât timp mimetismul față de predecesori pune stăpânire pe gândirea ideatică, cât timp adevărul științific se află în afara oricărei îndoieli, cercetătorul nu va face decât să crească numărul celor lipsiți de idei și interesați doar de chestiuni pecuniare. Prezenta lucrare, aduce în prim plan o abordare inedită a cercetării experimentale in vivo, prin analiza rezultatelor experimentale atât din perspectivă fiziopatologică cât și prin interpretarea acestora în raport cu modelul experimental folosit.
The florivorous apple blossom weevil, Anthonomus pomorum (Coleoptera: Curculionidae), is the most economically relevant insect pest of European apple orchards in early spring. Neither efficient monitoring nor ecologically sustainable management of this insect pest has yet been implemented. To identify heritable traits of apple trees that might influence the host selection of A. pomorum , we compared the susceptibility of apple tree species using infestation rates of the domesticated apple, Malus domestica (Rosaceae: Pyreae), and the European crab apple, M. sylvestris . We evaluated the suitability of the two apple species for A. pomorum by quantifying the mass of weevil offspring. Because volatile organic compounds (VOCs) emitted from flower buds of the domesticated apple have previously been suggested to mediate female weevil preference via olfactory cues, we conducted bioassay experiments with blossom buds of both apple species to explore the olfactory preference of adult weevils and, furthermore, identified the headspace VOCs of blossom buds of both apple species through GC-MS analysis. The infestation analysis showed that A. pomorum infested the native European crab apple more prevalently than the domesticated apple, which originated from Central Asia. The European crab apple also appeared to be better suited for weevil larval development than the domesticated apple, as weevils emerging from M. sylvestris had a higher body mass than those emerging from M. domestica . These field observations were supported by olfactory bioassays, which showed that A. pomorum significantly preferred the odor of M. sylvestris buds compared to the odor of M. domestica buds. The analysis of headspace VOCs indicated differences in the blossom bud volatiles separating several M. domestica individuals from M. sylvestris individuals. This knowledge might be employed in further studies to repel A. pomorum from M. domestica blossom buds.
Domestication process in long‐lived plant perennials differs dramatically from that of annuals, with a huge extent of genetic exchanges between crop and wild populations. Though apple is a major fruit crop grown worldwide, the contribution of wild apple species to the genetic makeup of the cultivated apple genome remains a topic of intense investigations. We used population genomics approaches to investigate the contributions of several wild apple species to European and Chinese rootstock and dessert genomes, with a focus on the extent of wild‐crop gene flow. Population genetic structure inferences revealed that the East Asian wild apples, M. baccata (L.) Borkh and M. hupehensis (Pamp.), form a single panmictic group, and that the European dessert and rootstock apples form a specific gene pool whereas the Chinese dessert and rootstock apples were a mixture of three wild gene pools, suggesting different evolutionary histories of European and Chinese apple varieties. Coalescent‐based inferences and gene flow estimates indicated that M. baccata‐M. hupehensis contributed to the genome of both European and Chinese cultivated apples through wild‐to‐crop introgressions, and not as an initial contributor as previously supposed. We also confirmed the contribution through wild‐to‐crop introgressions of M. sylvestris Mill. to the cultivated apple genome. Apple tree domestication is therefore one example in woody perennials that involved gene flow from several wild species from multiple geographic area. This study provides an overview of the complex protracted process of domestication in long‐lived plant perennials, and is a starting point for apple breeding programs.
The checklist includes tree, shrub, dwarf shrub, woody liana and epiphyte species that occur or have occurred in Hungary except the settlements and other intensively utilised objects. 437 dendrotaxa were included and evaluated in this list. This means 281 species, 22 subspecies, 128 nothospecies and 6 nothosubspecies. Based on the indigenat, 260 native, 92 alien and 9 cryptogenic dendrotaxa live in Hungary, furthermore 54 cultivated dendrotaxa and 22 dendrotaxa with questionable occurrence. Analysing the invasive status of alien species, 19 invasive or being in the early stages of invasion, 12 naturalised and 61 casual dendrotaxa can be distinguished. According to residence time status, the number of archaeophytes is 16 and that of neophytes is 76. Of the 260 native dendrotaxa, 9 were extinct or presumably extinct. 44 dendrotaxa are considered to be proven endemic, and there are 8 subendemic. Of the 134 nothotaxa on the list, 14 are artificial and 120 are of natural origin.
Malus baccata (L.) Borkh. and Malus toringo (Siebold) Siebold ex de Vriese of the genus Malus Mill. (Rosaceae) are wild crabapples occurring in temperate East Asia. Despite their horticultural importance as ornamental trees and the natural resources in apple breeding, their phylogenetic relationships have never been determined clearly owing to lack of resolution in previous studies. We characterized four complete chloroplast genomes of these two species and conducted various phylogenomic analyses comparatively to the previously reported plastomes of other wild Malus species. They were highly conserved in genomic structures and gene contents, containing 129 genes including 84 protein-coding genes, eight rRNA genes, and 37 tRNA genes. Phylogenetic analysis of 23 representative Malus plastomes did not support the current classification of the major sections in Malus, revealing non-monophylies. The plastomes of M. toringo revealed two chloroplast types corresponding to their geographic distribution; M. toringo from China was more closely related to other sympatric species, while two conspecific M. toringo from Japan and Korea were in a sister relationship with M. baccata from Korea. We identified one positively selected gene (ndhD) and seven mutation hotspots (trnK-rps16, trnR-atpA, petN-psbM, trnT-psbD, psbZ-trnG, ndhC-trnV, and ycf1) and variable SSRs as potential useful plastid markers.
Apples are important from both a cultural and nutritional standpoint. The fruit produced from the cultivated apple, Malus × domestica Borkh., is grown in temperate regions throughout the world. Ornamental crabapple trees represent other Malus species and are generally valued for their landscape properties rather than their fruits. Genetic analyses of apple cultivars and species have revealed domestication pathways, pedigree relationships, as well as data that guide genebank collection management practices. Molecular information is also critical for breeding programs that are using new techniques to identify novel genetic combinations with enhanced biotic and abiotic stress resistance as well as desirable fruit quality and production traits. This chapter includes information about wild apple species, origins of cultivated apples, genetic assessments, as well as some basic information about tree phenology, architecture, and propagation methods.
Although, the Pacific crabapple, Malus fusca, is a hardy and disease resistant species, studies relating to the genetics of its unique traits are very limited partly due to the lack of a genetic map of this interesting wild apple. An accession of M. fusca (MAL0045) of Julius Kühn-Institut collection in Germany is highly resistant to fire blight disease, incited by different strains of the causative pathogen—Erwinia amylovora. This is the most destructive bacterial disease of Malus of which most of the domesticated apples (Malus domestica) are susceptible. Using a scarcely dense genetic map derived from a population of 134 individuals of MAL0045 × ‘Idared’, the locus (Mfu10) controlling fire blight resistance mapped on linkage group 10 (LG10) and explained up to 66% of the phenotypic variance with different strains. Although the development of robust and tightly linked molecular markers on LG10 through chromosome walking approach led to the identification of a major candidate gene, any minor effect locus remained elusive possibly due to the lack of marker density of the entire genetic map. Therefore, we have developed a dense genetic map of M. fusca using tunable genotyping-by-sequencing (tGBS) approach. Of thousands of de novo SNPs identified, 2677 were informative in M. fusca and 90.5% of these successfully mapped. In addition, integration of SNP data and microsatellite (SSR) data resulted in a final map comprising 17 LGs with 613 loci spanning 1081.35 centi Morgan (cM). This map will serve as a template for mapping using different strains of the pathogen.
A historical analysis of apple nomenclature leads to the conclusion that the legitimate epithet for the cultivated apple is Malus Xdomestica Borkh.
Forty-five crabapple (Malus spp.) cultivars were evaluated for 16 isozyme systems by starch gel electrophoresis. Of the 16 systems evaluated, 6 were useful in separating among cultivars. Enzyme systems used to distinguish among the cultivars included alcohol dehydrogenase, aspartate aminotransferase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucoisomerase, and shikimate dehydrogenase. Each enzyme system produced one well-resolved polymorphic region except for 6-phosphogluconate dehydrogenase, which produced two. Most crabapple selections could be identified when all six enzymes were evaluated. Alcohol dehydrogenase had the most diagnostic banding patterns useful for cultivar identification.
The origin of domestication in Mesoamerican G. hirsutum populations is obscured by several factors, including the absence of a clearly identified wild progenitor, a complex population genetic structure, and many centuries of human-mediated dispersal and gene flow. Phenetic and phylogenetic analyses of allelic variation at 205 restriction fragment length polymorphism (RFLP) loci were conducted in an effort to unravel this complicated history. The RFLP data, in conjunction with previously published molecular, morphorogical, and anthropological information, suggest that coastal Yucatan populations are truly wild rather than reestablished feral derivatives. The geographical proximity of these wild coastal populations to agronomically primitive forms of G. hirsutum implicates the Yucatan peninsula as the primary site for the earliest stages of domestication. Agronomically advanced cultigens developed in southern Mexico and Guatemala appear to have been derived from introduced Yucatan peninsular forms, thereby creating the secondary center of diversity that has traditionally been interpreted as the geographical point of origin of domesticated G. hirsutum. The gene pool of modern, improved (Upland) cultivars derives from Mexican highland populations that, in turn, trace their origins to southern Mexico and Guatemala. Gossypium hirsutum is the first tetraploid perennial surveyed for RFLP variation. Levels of RFLP variation in G. hirsutum (H-T= 0.048, A = 1.24, and P = 22%) are low relative to other plant taxa, and, in contrast to the few comparable studies, levels of allozyme variation are higher than levels of RFLP variation. Despite assaying 205 loci, only six of the 23 Upland cultivars were found to have unique multilocus genotypes.
Summary 212 Genotypes of theMalus wild species collection in Dresden were analysed for their chromosome numbers. The most frequent chromosome number is 2n=2x=34.
Some genotypes are polyploid (2n=3x=51 or 2n=4x=68). The chromosome numbers of the following species are reported for the
first time:Malus x arnoldiana 2n=34,M. x dawsoniana, M. x moerlandsii 2n=34 andM. x sublobata 2n=34,M. trilobata 2n=34,M. tschonoskii 2n=34.
We used sequences from both internal transcribed spacers (ITS) and a small portion of the 5.8S gene of nuclear ribosomal DNA (nrDNA) for phylogenetic reconstruction of 19 genera of Maloideae and four potential outgroups from the Rosaceae. Parsimony analyses indicate that Maloideae are not monophyletic; Vauquelinia, which is traditionally placed in Spiraeoideae, and two genera of the Maloideae, Enriobotrya and Rhaphiolepis, form a well-supported clade that is the sister to the remainder of the subfamily. Although our ITS phylogenetic hypothesis is highly resolved, there is considerable homoplasy, and support, as indicated by bootstrap values and decay indices, is relatively weak for all groups except four: Eriobotrya-Rhaphiolepis-Vauguelinia, Crataegus-Mespilus, Amelanchier-Peraphyllum-Malacomeles, and Cydonia-Pseudocydonia. Our DNA sequence data do not support a broad interpretation of Sorbus. Intergeneric hybridization, which is prevalent in Maloideae, occurs between genera that are far removed from one another on our most-parsimonious trees. We infer an overall phylogeny from separate analyses of ITS DNA sequences and recently published morphological and wood anatomical studies of Maloideae and from analyses after pooling these data sets. The four most strongly supported clades of the ITS phylogeny appear in the phylogeny based on pooled data.
Genetic structuring of plant populations is strongly influenced by both common ancestry and current patterns of interpopulation genetic exchange. The interaction of these two forces is particularly confounding and hence interesting in plants. This complexity of plant genetic structures is due in part to a diversity of reproductive ecologies affecting genetic exchange and the fact that reproductive barriers are often weak between otherwise morphologically well-defined species. Phylogeographic methods provide a means of examining the history of genetic exchange among populations, with the potential to distinguish biogeographic patterns of genetic variation caused by gene flow from those caused by common ancestry. With regard to plants, phylogeography will be most useful when applied broadly across the entire spectrum of potential genetic exchange. Although current phylogeographic studies of plants show promise, widespread application of this approach has been hindered by a lack of appropriate molecular variation; this problem is discussed and possible solutions considered.
A collection of 66 Malus×domestica Borkh. accessions from the USDA-ARS Plant Genetic Resources Unit’s core collection was screened with a set of eight SSR (simple
sequence repeat) primers developed at the PGRU in order to determine genetic identities, estimate genetic diversity, and to
identify genetic relationships among these accessions. All eight primer pairs generated multiple fragments when used in amplification
reactions with DNA from these accessions. High levels of variation were detected with a mean of 12.1 alleles per locus and
a mean heterozygosity across all eight loci of 0.693. The eight primer pairs utilized in this study unambiguously differentiated
all but seven pairs of accessions in this collection of 66 M.×domestica Borkh. genotypes. The probability of matching any two genotypes at all eight loci in this study was approximately 1 in 1
billion. The markers detected two misnamed accessions in the collection. Genetic-identity data produced a genetic-relatedness
phenogram which was concordant with geographic origins and/or known pedigree information. These SSR markers show great promise
as tools for managing Malus ex situ germplasm collections as well as for collection and preservation strategies concerning wild Malus populations in situ.
Plant domestication includes a number of evolutionary mechanisms, such as mutation, hybridization, polyploidization, selection, and genetic drift. These evolutionary mechanisms will be used as entities in a graphical model system to be used as a formal descriptive method to describe the process of plant domestication. The most important crops can be arranged in four different crop domestication models: the bread wheat model, the cotton model, the soybean model, and the chili pepper model. Mixed-model situations occur. The existence of reproductive isolation connects the crop models with the gene pool concept. Cluster and analysis of taxa based on a numerical representation of crossability data allows a precise characterization of the different gene pools. The combined approach of crop domestication models, dendrograms, and gene pool representation creates a clear description of the mechanisms leading to a particular set of reproductive barriers and the extent of these barriers. The four models described here are general outlines. The included entities can be fine tuned to specific crop situations. This will be worked out for Allium cepa (onion) and Lesquerella densipila (an oil seed crop). These crop domestication models can also be used in developing breeding strategies by illustrating the rationale of desired approaches such as hybridization improvement techniques or transformation.
Cladistic parsimony analyses of rbcL nucleotide sequence data from 171 taxa representing nearly all tribes and subtribes of Orchidaceae are presented here. These analyses divide the family into five primary monophyletic clades: apostasioid, cypripedioid, vanilloid, orchidoid, and epidendroid orchids, arranged in that order. These clades, with the exception of the vanilloids, essentially correspond to currently recognized subfamilies. A distinct subfamily, based upon tribe Vanilleae, is supported for Vanilla and its allies. The general tree topology is, for the most part, congruent with previously published hypotheses of intrafamilial relationships; however, there is no evidence supporting the previously recognized subfamilies Spiranthoideae, Neottioideae, or Vandoideae. Subfamily Spiranthoideae is embedded within a single clade containing members of Orchidoideae and sister to tribe Diurideae. Genera representing tribe Tropideae are placed within the epidendroid clade. Most traditional subtribal units are supported within each clade, but few tribes, as currently circumscribed, are monophyletic. Although powerful in assessing monophyly of clades within the family, in this case rbcL fails to provide strong support for the interrelationships of the subfamilies (i.e., along the spine of the tree). The cladograms presented here should serve as a standard to which future morphological and molecular studies can be compared.
We used nuclear ribosomal DNA internal transcribed spacer region (ITS 1 - 5.8S - ITS 2; ITS) sequences to generate the first phylogeny of Rubus based on a large, molecular data set. We sampled 57 taxa including 20 species of subgenus Rubus (blackberries), one to seven species from each of the remaining 11 subgenera, and the monotypic and closely related Dalibarda. In Rubus, ITS sequences are most informative among subgenera, and variability is low between closely related species. Parsimony analysis indicates that Rubus plus Dalibarda form a strongly supported clade, and D. repens may nest within Rubus. Of the subgenera with more than one species sampled, only subgenus Orobatus appears monophyletic. Three large clades are strongly supported: one contains all sampled species of nine of the 12 subgenera; another includes extreme Southern Hemisphere species of subgenera Comaropsis, Dalibarda, and Lampobatus; and a third clade consists of subgenus Rubus plus R. alpinus of subgenus Lampobatus. Rubus ursinus appears to be a hybrid between a close relative of R. macraei (subgenus Idaeobatus, raspberries) and an unidentified subgenus Rubus species. ITS sequences are generally consistent with biogeography and ploidy, but traditionally important morphological characters, such as stem armature and leaf type, appear to have limited phylogenetic value in Rubus.
Polyploidy is a prominent process in plant evolution; yet few data address the question of whether homeologous sequences evolve independently subsequent to polyploidization. We report on ribosomal DNA (rDNA) evolution in five allopolyploid (AD genome) species of cotton (Gossypium) and species representing their diploid progenitors (A genome, D genome). Sequence data from the internal transcribed spacer regions (ITS1 and ITS2) and the 5.8S gene indicate that rDNA arrays are homogeneous, or nearly so, in all diploids and allopolyploids examined. Because these arrays occur at four chromosomal loci in allopolyploid cotton, two in each subgenome, repeats from different arrays must have become homogenized by interlocus concerted evolution. Southern hybridization analysis combined with copy-number estimation demonstrate that this process has gone to completion in the diploids and to completion or near-completion in all allopolyploid species and that it most likely involves the entire rDNA repeat. Phylogenetic analysis demonstrates that interlocus concerted evolution has been bidirectional in allopolyploid species--i.e., rDNA from four polyploid lineages has been homogenized to a D genome repeat type, whereas sequences from Gossypium mustelinum have concerted to an A genome repeat type. Although little is known regarding the functional significance of interlocus concerted evolution of homeologous sequences, this study demonstrates that the process occurs for tandemly repeated sequences in diploid and polyploid plants. That interlocus concerted evolution can occur bidirectionally subsequent to hybidization and polyploidization has significant implications for phylogeny reconstruction, especially when based on rDNA sequences.
Eighty-five wild and cultivated accessions of common bean (Phaseolus vulgaris L.), representing a wide geographic area in the centres of domestication were tested for restriction fragment length polymorphisms (RFLPs). Genomic DNA was digested with one of three restriction enzymes (EcoRI, EcoRV, and HindIII) and hybridized to 12 probes distributed throughout the common bean genome. Accessions could be classified into two major groups with a distinct geographical distribution in Middle America and the Andes. Within each gene pool, cultivated accessions clustered together with wild forms from the same geographical area supporting the multiple domestications hypothesis for this crop. Estimates of Nei's genetic distances among the cultivated races from the two different gene pools varied from 0.12 to 0.56 and among races from the same gene pool from 0.04 to 0.12, suggesting that the divergence in Phaseolus vulgaris has reached the subspecies level. The level of genetic diversity (Ht = 0.38) was twice the value obtained with isozyme analysis. Genetic diversity within races (Hs = 0.27) was four to five times higher compared with isozymes, but genetic diversity between races (Dst = 0.11) was similar for both categories of markers. These results corroborate previous studies on the characterization of genetic diversity in common bean that clearly showed two distinct gene pools, Middle American and Andean. Moreover, RFLP markers are superior to isozymes because they provide better coverage of the genome and reveal higher level of polymorphisms.
Subfam. Maloideae (x = 17) has been held to be tetraploid since 1931 while later, Sax elaborated by Stebbins, specifically implicated subfam. Spiraeoideae (x = 9) and Amygdaloideae (x = 8) in an allotetraploid ancestry. The allotetraploid theory has gained considerable credibility with many workers on Rosaceae but, although support for it is not unanimous, and it is sometimes ignored, there has never been any attempt at refutation. To date, the theory has depended mainly on chromosome constitution, and, in a rather general way, on the morphological characteristics of the respective taxa. In this paper we review the allotetraploid hypothesis and generally verify it by an extensive character analysis of the Maloideae, Amygdaloideae, and Spiraeoideae. Since no specifically rosoid or quillajoid characters exist in the Maloideae, no candidate near-ancestral genera in subfam. Rosoideae or tribe Quillajeae can be pinpointed. The autapomorphic fruit of the Maloideae-the pome-is derivable from spiraeoid or proto-amygdaloid characters. In a parsimony analysis of a 96 taxa x 36 variable data matrix the phenetic genera were, for the most part, returned as clades, but their placement was to a significant extent, peculiar. The consistency index was extremely low. Furthermore, the addition of only three OTUs resulted in major relocations of some of the genera. We concluded that, in this type of situation, parsimony analysis is not robust, and sought other explanations for the relationships suggested. We favour the idea that several clades of Maloideae originated independently in a highly reticulate system existing shortly after the original allotetraploid cross. This notion of polychotomous early evolution alone, we feel, makes sense of the general correspondence of phenetic genera to cladistic genera, remarkably low consistency index, great instability of the cladogram with respect to changing only a few OTU's, and the manifestly great ability of most maloidean genera to hybridize. Thus, the precise phylogeny of the Maloideae must remain quite unknown until a very different kind of investigation has been successfully conducted.
... THE IMPACT OF HYBRIDS ON CLADISTIC ANALYSIS Lucinda A. McDade Department of Botany, Duke University, Durham ... Acanthaceae, Aphelandra, cladistics , hybrids, phylogenetic ... Interspecific hybridization is thought to bridization is thought to be of less evolu- be common ...
Restriction fragment length polymorphisms (RFLP) were assessed among accessions within six peanut species of the Arachis section: tetraploid cultivated species, A. hypogaea; tetraploid wild species, A. monticola; and four diploid wild species, A. batizocoi,A. cardenasii, A. duranensis and A. glandulifera. While the two tetraploid species did not show polymorphism with 16 PstI-generated random genomic probes, two of seven seed cDNA probes detected polymorphisms. The RFLP variation detected by two seed cDNA probes appeared to be related to structural changes occurring within tetraploid species. The botanical var. 'fastigiata' (Valencia market type) of A. hypogaea subspecies fastigiata was shown to be the most variable. Arachis monticola was found to be more closely related to A. hypogaea subspecies hypogaea than to subspecies fastigiata. Diploid species A. cardenasii, A. duranensis, and A. glandulifera showed considerable intraspecific genetic diversity, but A. batizocoi showed little polymorphism. The genetic distance between the cultivated peanut and wild diploid species was found to be closest for A. duranensis.
Eleven apple cultivars were differentiated using randomly amplified polymorphic DNA (RAPD) markers obtained by the polymerase chain reaction (PCR). The variability of the technique and of the origin of the DNA extract was analyzed. A set of bands consistent in their presence or absence was chosen to create a differentiating band pattern. A key is proposed by which one can differentiate apple cultivars using commercially available prime.
RAPD (random amplified polymorphic DNA) markers were used to fingerprint eight commercially available apple rootstocks (Nertchinsk, Northern Spy, Osman, Heyer 12, M.1, M.9, M.26 and MM.106), 10 winter hardy offsprings derived from the cross of Nertchinsk x M.9, six winter hardy offsprings derived from the cross of Nertchinsk x M.26 and one winter hardy offspring derived from each of the two crosses between Osman x Heyer 12 and Northern Spy x M.1. Phylogeny analysis using parsimony allowed us to draw the genetic relationship between these lines using only RAPD markers data. The resulting cladogram was compared to the true genetic relationship between these lines in order to assess the efficiency of RAPD markers in determining accurately the phylogenetic relationship. We also developed a DNA fingerprinting system based on 13 informative RAPD loci amplified by five RAPD primers that allowed the rapid identification of apple rootstocks.
Five chloroplast DNA (ctDNA) types (W, T, C, S, and A) have previously been identified in the Andean tetraploid cultivated potatoes (Solanum tuberosum ssp. andigena) and three types (C, S, and A) in diploid cultivated potatoes (S. stenotomum). In this study, ctDNA types were determined for an additional 35 accessions of S. stenotomum and 97 accessions of putative ancestral wild species (15 of S. brevicaule, 26 of S. bukasovii, 4 of S. candolleanum, 25 of S. canasense, 17 of S. leptophyes, and 10 of S. multidissectum). The first five ctDNA types were also identified in S. stenotomum. The wild species were also polymorphic for ctDNA types except for S. brevicaule, which had only W-type ctDNA. T-type ctDNA was not found in any of the wild species and could have originated from W-type ctDNA after S. stenotomum arose. The other types of ctDNA evolved in wild species. The geographical distribution of each ctDNA type indicated that A-type ctDNA arose in central Peru and T-type ctDNA in the Bolivia-Argentine boundary. It is implied that potatoes were successively domesticated and that, in parallel, several wild species were differentiated from time to time and place to place from the 'ancestral species' complex. Subsequent sexual polyploidization formed a wide ctDNA diversity among the Andean tetraploid potatoes, and selection from them formed the limited ctDNA diversity found in Chilean tetraploid potatoes (ssp. tuberosum).
The chloroplastic atpB-rbcL spacer and the first 53 codons of the rbcL coding sequence was sequenced for 40 apple cultivars and 15 wild species. This chloroplast DNA region is 904 base pairs long, and only five mutations sites were found among the tested samples. Although the cpDNA variation was low, some parentages are proposed based on the maternal inheritance of plastid DNA: the male and female parents are specified, or else suggested, for Worcester, Discovery, Starking, Starkrimson, Kidd's Orange Red, Priscilla, and Gloster, as well as for the putative wild origin for Malus x domestica.
Phylogenetic relationships between 14 wild and 3 cultivatedSolanum species, including the European potato,Solanum tuberosum ssp.tuberosum, were inferred using DNA restriction fragment length polymorphisms (RFLPs) as discriminating characters. Phenetic trees were obtained based on distance matrices as well as on parsimony methods, which were not significantly altered either by the computational method used, or by the individual plant genotypes or RFLP markers chosen for the analysis. The reliability of the tree topologies was assessed and, as expected, it increased with the number of polymorphic restriction fragments scored. The individual genotypes within each species, the different species themselves, and the main branches of the trees were clearly separated from each other. The least reliable parts in the trees were the positions of closely related species within the main clusters.S. tuberosum spp.tuberosum formed one group closely related withS. tuberosum spp.andigena,S. stenotomum, andS. canasense. This was well separated from a second group formed byS. sparsipilum,berthaultii,kurtzianum,gourlayi,vernei,spegazzinii,chacoense, andmegistacrolobum. Two further branches were formed byS. demissum andS. acaule, and byS. polyadenium,S. pinnatisectum,S. stoloniferum, andS. etuberosum. The phenetic trees presented here supported the description of relationships amongSolanum species based on biosystematic studies, with the exception of the placement ofS. chacoense andS. megistacrolobum.
Flowers of 169 species of Rosaceae subfamily Maloideae, which were chosen to represent the taxonomic and geographic diversity of the group, were studied to ascertain their morphological variation and its systematic relevance. We describe and illustrate variation in size, indumentum, color, and macroscopic structural features. Most maloid species have syncarpous flowers with two to five carpels in which the ovary is at least three-quarters inferior, whereas species of other Rosaceae subfamilies have apocarpous or unicarpellate flowers with superior ovaries. However, maloid flowers show significant variation in the degree of carpel connation and of ovary adnation to the hypanthium. Coloneaster, Heteromeles, and Pyracantha are completely apocarpous, and Dichotomanthes is perigynous with a completely superior ovary. Thus, no one floral character is sufficient to separate the Maloideae from other subfamilies of Rosaceae. Differences among their flowers support our recognition of Malus, Pyrus, and Sorbus as separate genera. Further, we argue for removal of Docyniopsis and Eriolobus from Malus. division of Sorbus into several genera, and union of Aronia, Photinia, and Stranvesia. No floral characters support the traditional dichotomy of the subfamily into tribes Crataegeae and Sorbeae.
The emergence of agriculture in the Near East also involved the domestication of einkorn wheat. Phylogenetic analysis that
was based on the allelic frequency at 288 amplified fragment length polymorphism molecular marker loci indicates that a wild
group of Triticum monococcum boeoticum lines from the Karacadağ mountains (southeast Turkey) is the likely progenitor of cultivated einkorn varieties. Evidence
from archeological excavations of early agricultural settlements nearby supports the conclusion that domestication of einkorn
wheat began near the Karacadağmountains.
The potential use of RAPD markers for taxonomic studies in Malus was investigated using 18 accessions of wild species and 27 apple cultivars. 29 preselected random decamer primers were applied to three sets of Malus genotypes. Random amplified polymorphic DNA (RAPD) ‘fingerprints’ were analysed for polymorphic amplification fragments, and coefficients estimating genetic similarity were calculated on the basis of about 50 polymorphic RAPD loci in each set of genotypes. Cluster analysis by an unweighted pair-group method with arithmetic averages (UPGMA) revealed that, in the cultivars, the molecular classification was in good agreement with the known lineage. A dendrogram generated for the wild species gave relationships that were, in principle, in accordance with the known phylogenetic information. Closely related species from section I were clearly distinguishable from those of sections III and IV. On the molecular level, a high degree of genetic diversity was found among both different apple cultivars and wild species of the genus Malus. The results gave additional evidence for the hypothesis that M. pumila and M. sylvestris were involved in the origin of the cultivated apples.
TheSolanum brevicaule complex is a group of morphologically very similar wild and cultivated potato taxa (Solanum sect.Petota). This study uses single to low-copy nuclear RFLPs and RAPDs to investigate their species boundaries and relationships. Cladistic analyses of both data sets are largely concordant with each other and with a recently published phenetic analyses of the same accessions using morphology. All three data sets separate members of the complex into populations from Peru and immediately adjacent northwestern Bolivia, including most cultivated species accessions, and populations from northwestern Bolivia to Argentina. The molecular results suggest that the complex is paraphyletic as currently circumscribed. Many species of theS. brevicaule complex should be relegated to synonymy.
The recent accumulation of cytogenetic evidence on the ancestry of the earliest domesticated plants provides an empirical test of the relative importance of independent invention and diffusion in the origin and spread of agriculture. The most parsimonious interpretation of the data is that plant species were domesticated no more than a few times, and perhaps only once, in the Near East and Mexico. Multiple domestications of species may have taken place in the central Andes, but it is impossible to say whether any such cases were truly independent, because of the scantiness of the archaeological as well as botanical record. Evidence from other agricultural centers is limited, and does not negate the conclusion that multiple independent domestications within regions were rare, while domestications of the same species or genus in different regions did not occur as frequently as some authorities have claimed. The prevailing tendency to interpret archaeological sequences as almost entirely the result of local in situ development is not entirely in accord with theory, nor with the genetic evidence summarized here.
The origin of avocado (Persea americana Mill) cultivars, as well as the genetic relationships between Persea species, are not well defined and are based mainly on morphological parameters. Minisatellite DNA markers were used to analyze
24 P. americana cultivars in an attempt to define their racial allocation. DNA mixes representing the three races were evaluated and used
for analysis. The allocation of 19 of the above cultivars was substantiated by the DNA markers, while new suggestions were
offered regarding the remaining five. Eight cultivars, of unknown racial origin, were also examined, and a phylogenetic tree
suggesting their origin is offered. Selfing progeny of five cultivars were analyzed for six morphological traits which differentiate
the three races, and were compared to their parents in order to assess their origin. Eleven Persea species were analyzed, using DNA fingerprint patterns and SSR (simple sequence repeat) alleles, in order to identify the
genetic relationships among the Persea species, and between them and the three P. americana races. The phylogenetic tree obtained is presented. The high value of variation between the avocado cultivars and Persea species observed in this work, suggests that the validity of race and species definition within Persea be treated with caution.
Earlier analyses of chloroplast and mitochondrial DNA restriction site variations within 17 rose species gave two to three groups based on the cytoplasmic relatedness. The species were from seven sections within the subgenus Rosa. This study investigated the molecular systematics based on the cytoplasmic relatedness of the genus Rosa. Included in our study were the subgenera Hulthemia, Platyrhodon, and Hesperhodos, and the sections Indicae, Laevigatae and Bracteatae in the subgenus Rosa, all of which had not been examined previously. We used matK sequence variation for detailed analysis of phylogenetic relationships. Our molecular classification conformed closely to the traditional classification of botanical sections. Six out of the seven original species that contributed to modern roses were found to belong to only one clade. This confirms the narrow genetic background of modern roses.
The internal transcribed spacers (ITS) of nuclear ribosomal DNA of 33 species of genus Paeonia (Paeoniaceae) were sequenced. In section Paeonia, different patterns of nucleotide additivity were detected in 14 diploid and tetraploid species at sites that are variable in the other 12 species of the section, suggesting that reticulate evolution has occurred. Phylogenetic relationships of species that do not show additivity, and thus ostensibly were not derived through hybridization, were reconstructed by parsimony analysis. The taxa presumably derived through reticulate evolution were then added to the phylogenetic tree according to additivity from putative parents. The study provides an example of successfully using ITS sequences to reconstruct reticulate evolution in plants and further demonstrates that the sequence data could be highly informative and accurate for detecting hybridization. Maintenance of parental sequences in the species of hybrid origin is likely due to slowing of concerted evolution caused by the long generation time of peonies. The partial and uneven homogenization of parental sequences displayed in nine species of putative hybrid origin may have resulted from gradients of gene conversion. The documented hybridizations may have occurred since the Pleistocene glaciations. The species of hybrid origin and their putative parents are now distantly allopatric. Reconstruction of reticulate evolution with sequence data, therefore, provides gene records for distributional histories of some of the parental species.
Phylogenetic relationships of 30 diploid species of Triticeae (Poaceae) representing 19 genomes were estimated from the sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The ITS sequence phylogeny indicated that: (i) each genome group of species is monophyletic, concordant with cytogenetic evidence; (ii) Hordeum (I) and Critesion (H) are basal; (iii) Australopyrum (W) is closely related to Agropyron (P); (iv) Peridictyon (G), Heteranthelium (Q), and Dasypyrum (V) are closely related to Pseudoroegneria (S); (v) most of the annuals, Triticum s.l. (A, B, D), Crithopsis (K), Taeniatherum (T), Eremopyrum (F), Henrardia (O), Secale (R), and two perennials, Thinopyrum (J) and Lophopyrum (E), all of Mediterranean origin, are a monophyletic group. However, phylogenetic trees based on morphology group these Mediteranean species with various perennial lineages of the Arctic-temperate region. The molecular data and biogeography of the tribe suggest that the Mediterranean lineage is derived from the Arctic-temperate lineage and that the two lineages have evolved in parallel. Extensive morphological parallelism apparently obscures the true genealogical history of the tribe when only morphology is considered.
Nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences from artificial hybrids and backcrosses between Armeria villosa ssp. longiaristata and A. colorata were studied to assess the possible effects of concerted evolution in natural hybrids. F1 artificial hybrids show the expected pattern of additive polymorphisms for five of the six variable sites as estimated from direct sequences. However, homogenization of polymorphism is already observed in the F2, and is biased towards A. colorata except for one site. In backcrosses, an expected tendency towards homogenization of polymorphic sites in the direction of the recurrent parent is observed for five sites, although this does not necessarily imply concerted evolution. Conversely, the sixth site appears to elude such a mechanism and thus provides additional support for the occurrence of biased concerted evolution. Our findings are relevant to interpreting phylogeographic patterns involving gene flow and are also consistent with the hypothesis of a hybrid origin of A. villosa ssp. carratracensis.
The article reviews the available information on the start of fruit tree cultivation in the Old World. On the basis of (i) evaluation of the available archeological remains and (ii) examination of the wild relatives of the cultivated crops, it was concluded that olive, grape, date, and fig were the first important horticultural additions to the Mediterranean grain agriculture. They were most likely domesticated in the Near East in protohistoric time (fourth and third millennia B.C.) and they emerge as important food elements in the early Bronze Age.
Domestication of all four fruit trees was based on a shift from sexual reproduction (in the wild) to vegetative propagation of clones (under domestication). Olive, grape, date, and fig can be vegetatively propagated by simple techniques (cuttings, basal knobs, suckers) and were thus preadapted for domestication early in the development of agriculture.
The shift to clonal propagation placed serious limitations on selection and on fruit set under cultivation. We have examined the consequences of this shift in terms of the genetic makeup of the cultivars and traced the various countermeasures that evolved to ensure fruit set.
Finally, it was pointed out that in each of these classic fruit trees we are confronted with a variable complex of genuinely wild types, secondary weedy derivatives and feral plants, and groups of the domesticated clones, which are all interfertile and interconnected by occasional hybridization. It was concluded that introgression from the diversified wild gene pool facilitated the rapid buildup of variation in the domesticated crops.
Identifying Crabapple cultivars by isozymes Phylogenetic analyses of the genus Rosa using the matK sequence: molecular evidence for the narrow genetic background of modern roses Hybrids and phylogenetic systematics II. The impact of hybrids on cladistic analysis
- R D Marquard
- C R Chan
- ±
- S Matsumoto
- M Kouchi
- J Yabuki
- M Kusunoki
- Y Ueda
- H Fukui
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