Fig 15 - uploaded by Aveliano Fernandez
Content may be subject to copyright.
Cromosomas somáticos de Arachis. A. helodes (6325) 2n=20: A, metafase. A. Kuhlmannii, 2n=20: B, 6344, metafase; e y D, 30017, profase y metafase respectivamente. A. stenosperma (410), 2n=20: E, metafase. A. villosa (357), 2n=20: F, metafase. A. hypogaea ssp. hypogaea varo hypogaea (Nambiquarae), 2n=40: G, profase, 2n=40. Escala igual a 5 pm. Cromosomas SAT: .... brazo 1 + segmento proximal, i satélite. Cromosomas l/A": 1\. Centrómero extendido: 1. Flechas blancas: coloración diferencial.
Source publication
Fueron analizadas citológicamente cuarenta y un especies pertenecientes a ocho de las nueve secciones del género Arachis. Se analizaron en detalle los cariotipos veinticuatro de las cuarenta y un especies. Todas las especies tienen un par de cromosomas con satélite, excepto A. valida, que tiene dos pares. Los satélites se clasifican en diez tipos....
Citations
... Genotyping data using the 48 (Table 1). For PI 468319, SNP data were obtained from four individuals to account for the genetic variation observed within the accession. ...
... Results from the analysis of population structure presented here support previous findings documenting the complex patterns of genetic variability of A. duranensis [2,7,48]. The number of accessions and molecular markers used in the analysis allowed for the detection of admixed genomes and the estimation of their ancestry proportions. ...
The genetic diversity that exists in natural populations of Arachis duranensis , the wild diploid donor of the A subgenome of cultivated tetraploid peanut, has the potential to improve crop adaptability, resilience to major pests and diseases, and drought tolerance. Despite its potential value for peanut improvement, limited research has been focused on the association between allelic variation, environmental factors, and response to early (ELS) and late leaf spot (LLS) diseases. The present study implemented a landscape genomics approach to gain a better understanding of the genetic variability of A . duranensis represented in the ex-situ peanut germplasm collection maintained at the U.S. Department of Agriculture, which spans the entire geographic range of the species in its center of origin in South America. A set of 2810 single nucleotide polymorphism (SNP) markers allowed a high-resolution genome-wide characterization of natural populations. The analysis of population structure showed a complex pattern of genetic diversity with five putative groups. The incorporation of bioclimatic variables for genotype-environment associations, using the latent factor mixed model (LFMM2) method, provided insights into the genomic signatures of environmental adaptation, and led to the identification of SNP loci whose allele frequencies were correlated with elevation, temperature, and precipitation-related variables ( q < 0.05). The LFMM2 analysis for ELS and LLS detected candidate SNPs and genomic regions on chromosomes A02, A03, A04, A06, and A08. These findings highlight the importance of the application of landscape genomics in ex situ collections of peanut and other crop wild relatives to effectively identify favorable alleles and germplasm for incorporation into breeding programs. We report new sources of A . duranensis germplasm harboring adaptive allelic variation, which have the potential to be utilized in introgression breeding for a single or multiple environmental factors, as well as for resistance to leaf spot diseases.
... & Rigoni are allotetraploids (2n=4x=40) with a genome formula AABB (Lavia et al., 2009;Stalker, 2017 and references therein; Seijo et al., 2021). Six genome types, A, B, D, F, K, and G, have been described for the diploid species in section Arachis, differing on the chromosome morphology, distribution patterns of heterochromatic bands and rDNA loci, and cross-compatibility (Smartt et al., 1978;Stalker, 1991;Fernandez and Krapovickas, 1994;Robledo and Seijo, 2010;Silvestri et al., 2015). ...
Introduction
Fungal foliar diseases can severely affect the productivity of the peanut crop worldwide. Late leaf spot is the most frequent disease and a major problem of the crop in Brazil and many other tropical countries. Only partial resistance to fungal diseases has been found in cultivated peanut, but high resistances have been described on the secondary gene pool.
Methods
To overcome the known compatibility barriers for the use of wild species in peanut breeding programs, we used an induced allotetraploid (Arachis stenosperma × A. magna)4x, as a donor parent, in a successive backcrossing scheme with the high-yielding Brazilian cultivar IAC OL 4. We used microsatellite markers associated with late leaf spot and rust resistance for foreground selection and high-throughput SNP genotyping for background selection.
Results
With these tools, we developed agronomically adapted lines with high cultivated genome recovery, high-yield potential, and wild chromosome segments from both A. stenosperma and A. magna conferring high resistance to late leaf spot and rust. These segments include the four previously identified as having QTLs (quantitative trait loci) for resistance to both diseases, which could be confirmed here, and at least four additional QTLs identified by using mapping populations on four generations.
Discussion
The introgression germplasm developed here will extend the useful genetic diversity of the primary gene pool by providing novel wild resistance genes against these two destructive peanut diseases.
... Brazil is the largest holder of wild Arachis, as 65 species of all nine sections occur in its territory and 46 are exclusive to the country. Most of the Arachis species are diploid with 2n = 2x = 20, five are tetraploid (2n = 4x = 40), and four are aneuploid or dysploid, with 2n = 2x = 18 chromosomes (Fernández and Krapovickas 1994;Krapovickas and Gregory 1994;Lavia 1998;Peñaloza and Valls 2005;Ortiz et al. 2017;Silvestri et al. 2017). ...
... The section Arachis is the most important because it contains the cultivated A. hypogaea, and its wild progenitors: A. duranensis and A. ipaënsis (Kochert et al. 1996;Seijo et al. 2004;Fávero et al. 2006;Grabiele et al. 2012;Moretzsohn et al. 2013;Bertioli et al. 2016). Within section Arachis, six genome types (A, B, D, F, G, and K) have been described, based on classical and molecular cytogenetic studies (Husted 1933;Stalker 1991;Fernández and Krapovickas 1994;Seijo 2008, 2010;Silvestri et al. 2015). Most species in the Arachis section have an A genome type, characterized by the presence of a so-called A chromosome pair, which has a reduced size (Husted 1936) and a lower level of euchromatin condensation in comparison to the other chromosomes (Seijo et al. 2004). ...
... Arachis glandulifera was also placed in Group 3. This D genome species has a unique karyotype within section Arachis (Stalker 1991;Fernández and Krapovickas 1994;Samoluk et al. 2019), but FISH mapping of rRNA loci and DAPI banding have shown homologies between A. glandulifera and A. batizocoi (Robledo and Seijo 2008). Additionally, A. glandulifera tends to group with the K genome species, when analyzed by molecular markers (Moretzsohn et al. 2004(Moretzsohn et al. , 2013Tallury et al. 2005;Bechara et al. 2010). ...
The genus Arachis is endemic to South America and contains 83 described species assembled into nine taxonomical sections. The section Arachis is of particular interest because it includes the cultivated peanut (A. hypogaea) and its closely related wild species. In this study, we used 26 microsatellite markers to analyze the genetic variability and relationships of some recently collected germplasm accessions of species in the Arachis section, with emphasis on the B genome species. The knowledge of the genetic relationships among species and accessions is necessary for a more efficient management of germplasm collections and use of wild species for crop improvement. This is especially important for the B genome species, as only one accession of A. ipaënsis, the B genome donor to the allotetraploid A. hypogaea (AABB), is available in germplasm collections worldwide. The results shed more light on the genetic relationships between accessions of A. ipaënsis, A. gregoryi, A. magna, A. valida and A. williamsii, what expands the number of accessions for incorporation of useful genes from the species associated with the peanut B genome. The analyses also showed a generally high level of intraspecific genetic variability, but usually grouped the accessions according to their genome types and species. However, accessions of some species did not group as expected, and these results suggest the need of further taxonomic revision of a few taxa, especially some accessions of A. gregoryi, A. magna and A. kuhlmannii and the circumscriptions of sections Erectoides and Procumbentes.
... This species was formerly considered to belong to the B genome group, but it was reassigned to the F genome, due to differences in amount and distribution of heterochromatin and the presence of centromeric bands (Robledo and Seijo 2010). Arachis benensis is a peculiar species, since it has the type 9 satellited chromosome that is typical of section Procumbentes (Fernández and Krapovickas 1994 from the B genome species and also support the validity of the genome reassignment made by Robledo and Seijo (2010). ...
... Additionally, species that currently belong to these three sections were formerly classi ed in the section Erectoides (Krapovickas 1969;Gregory et al. 1973). Their separation into three sections was based on cytogenetic (Fernández and Krapovickas 1994) and hybridization studies (Gregory and Gregory 1979;Krapovickas and Gregory 1994), which included only one (A. lignosa) of the four species of section Procumbentes included in this study. ...
... ;Fernández and Krapovickas 1994;Samoluk et al. 2019), but FISH mapping of rRNA loci and DAPI banding have shown homologies between A. glandulifera and A. batizocoi(Robledo and Seijo 2008). Additionally, A. glandulifera tends to group with the K genome species, when analyzed by molecular markers(Moretzsohn et al. 2004; Tallury et al. 2005; Bechara et al. 2010; Moretzsohn et al. 2013). ...
The genus Arachis is endemic to South America and contains 83 described species assembled into nine taxonomical sections. The section Arachis is of particular interest because it includes the cultivated peanut ( A. hypogaea ) and its closely related wild species. The knowledge of the genetic relationships among species and accessions is necessary for a more efficient management of germplasm collections and use of wild species for crop improvement. In this study, we used 26 microsatellite markers to analyze the genetic variability and relationships of some recently collected accessions of species in the Arachis section, with emphasis on the B genome species. The analyses showed a generally high level of intraspecific genetic variability, but usually grouped the accessions according to their genome types and species. However, accessions of some species did not group as expected, and these results suggest the need of further taxonomic revision of a few taxa, especially some accessions of A. gregoryi , A. magna and A. kuhlmannii and the circumscriptions of sections Erectoides and Procumbentes .
... Around 5-10 mm of at least five root tips was collected from 4-week-old plants (5 plants for each genotype) and treated with 2 mM 8-hydroxyquinoline for 2 h at room temperature followed by an extra hour at 4 °C with fresh hydroxyquinoline solution (Fernández and Krapovickas, 1994). The samples were incubated in the fixative solution containing absolute ethanol:glacial acetic acid (3:1, v/v) for 12 h at 4 °C and the spreads of somatic chromosomes were prepared according to the previous protocol (Schwarzacher and Heslop-Harrison 2000). ...
Telomeres are the physical ends of eukaryotic linear chromosomes that play critical roles in cell division, chromosome maintenance, and genome stability. In many plants, telomeres are comprised of TTTAGGG tandem repeat that is widely found in plants. We refer to this repeat as canonical plant telomeric repeat (CPTR). Peanut (Arachis hypogaea L.) is a spontaneously formed allotetraploid and an important food and oil crop worldwide. In this study, we analyzed the peanut genome sequences and identified a new type of tandem repeat with 10-bp basic motif TTTT(C/T)TAGGG named TAndem Repeat (TAR) 30. TAR30 showed significant sequence identity to TTTAGGG repeat in 112 plant genomes suggesting that TAR30 is a homolog of CPTR. It also is nearly identical to the telomeric tandem repeat in Cestrum elegans. Fluorescence in situ hybridization (FISH) analysis revealed interstitial locations of TAR30 in peanut chromosomes but we did not detect visible signals in the terminal ends of chromosomes as expected for telomeric repeats. Interestingly, different TAR30 hybridization patterns were found between the newly induced allotetraploid ValSten and its diploid wild progenitors. The canonical telomeric repeat TTTAGGG is also present in the peanut genomes and some of these repeats are closely adjacent to TAR30 from both cultivated peanut and its wild relatives. Overall, our work identifies a new homolog of CPTR and reveals the unique distributions of TAR30 in cultivated peanuts and wild species. Our results provide new insights into the evolution of tandem repeats during peanut polyploidization and domestication.
... The genus Arachis is related to the genera Stylosanthes, Chapmannia, Arthrocarpum and Pachecoa in the sub-tribe Stylosanthinae of the tribe Aeschynomeneae on the basis of the shared morphological characters of a staminal tube with alternately attached basal and dorsal anthers, flowers in terminal or axillary spikes or small heads (which are sometimes raceme-like), pinnate leaves and leaflets without stipules. The taxonomic treatment of the cultivated groundnut is as follows: Based on geographic distribution, cross compatibility, cytogenetic behaviour and morphology, Arachis species have been grouped to nine taxonomic sections: Trierectoides, Erectoides, Procumbentes, Rhizomatosae, Heteranthae, Caulorrhizae, Extranervosae, Triseminatae and Arachis (Fernandez and Krapovickas 1994;Krapovickas and Gregory 1994;Lavia 1999;Valls and Simpson 2005). The section Arachis includes both annual and perennial species of different chromosome numbers, ploidy levels and karyotype. ...
... Stalker (1991) described A. glandulifera Stalker as 'D' genome species while the B genome was divided into B, F and K genomes by Seijo et al. (2004) and Robledo and Seijo (2010). As compared to A genome species the B genome species are karyotypically more diverse (Fernandez and Krapovickas 1994;Seijo et al. 2004). On the basis of cross-compatibility data, it was inferred that the evolution of the genomic groups in the genus mainly followed sectional designations ( (Smartt and Stalker 1982;Stalker 1991). ...
Groundnut or peanut is one of the major oilseeds and food crops cultivated globally. This oilseed can be directly consumed as a foodstuff, is a rich source of oil, protein and carbohydrates and other nutrition like tocopherol, niacin and folic acid; mineral components like Cu, Mn, K, Ca and P; dietary fibres, flavonoids, phytosterols like resveratrol, beta-sitosterol; and phenolic acids. The cultivated groundnut Arachis hypogea is a segmental amphidiploid (4x = 40), and cytogenetic and molecular evidences suggest that the origin of cultivated groundnut was from a hybridization of two diploid wild species Arachis duranensis (AA) and Arachis ipaensis (BB). Eighty-three species of Arachis have been described and most of species in the genus Arachis are diploid with x = 10 (2n = 20), while a few aneuploid (2n = 2x = 18) and tetraploid (2n = 4x = 40) species are also reported, and new taxa continue to be discovered. Higher yield has been the most frequently targeted trait in the breeding programmes, and the enhanced yield attained in the Indian cultivars has been attributed to the improvement in seed size, seed weight, and number of pods per plant. The other trait which have been in focus is tolerance/resistance to diseases and drought, which have been the major production constraints. Improving quality of the produce also is now being taken up in addition to enhancement of yield. Early leaf spot (ELS; caused by Cercospora arachidicola), late leaf spot (LLS; caused by Phaeoisariopsis personata) and rust (caused by Puccinia arachidic) are the most prevalent foliar fungal diseases in groundnut. Among the viral diseases reported in groundnut from India, peanut bud necrosis virus (PBNV), tobacco streak virus (TSV), peanut mottle virus (PeMoV), and Indian peanut clump virus (IPCV) are the economically important. Among nematodes, peanut root-knot nematode (Meloidogyne spp.) and the root-lesion nematode (Pratylenchus brachyrus) are prominent. The breeding programmes across the groundnut growing countries mainly focus on these.
... Section Arachis is the largest and more diverse taxonomic section of the homonymous genus (Krapovickas et Gregory 1994;Valls et Simpson 2005). It is composed of 31 species arranged in six different genomes: A, B, D, F, G and K, with two different basic chromosome numbers (x= 9, 10) and ploidy (2x and 4x) levels (Smartt et al., 1978;Gregory et Gregory, 1979;Fernández et Krapovickas 1994;Stalker, 1991;Seijo et al., 2004Seijo et al., , 2007Robledo et Seijo, 2008, 2010Robledo et al., 2009;Silvestri et al. 2015). Germplasm of these wild species (mainly with 2n= 2x= 20) is economically important, because they are the Seijo, G. J., M. Atahuachi, C. E. Simpson & A. Krapovickas. ...
Great efforts have been done to collect germplasm of the Arachis genus in South America, however, many regions still remain underexplored. Under the hypothesis that these regions have new and diverse populations/species of Arachis, several expeditions were carried out since 2000 in Bolivia, to increase the documentation of the genus diversity. As a first result of these explorations, a new species of section Arachis with B genome is formally described. Arachis inflata is closely related to A. magna and A. ipaënsis, but it can be clearly distinguished from them, and from any other species of the genus, for having a type of fruit with a completely distinct morphology. The fruit has a smooth epicarp, but shows a bullated aspect, due to the presence of air chambers in the mesocarp.
... As a member of the Dalbergioids clade, peanut shows a lot of atypical features of development, as well as atypical symbiosis. The cultivated peanut A. hypogaea is polyploid (Husted 1936;Fernández and Krapovickas 1994), unlike all other related diploid (2n = 2 × = 20 chromosomes) species in the genus Arachis. About 9,400 years ago (Bertioli et al. 2016), human-influenced hybridization of two diploid parental genotypes A. ipaensis and A. duranensis gave rise to A. hypogaea. ...
The phytohormone auxin is involved in the regulation of plant growth, nutrient acquisition, and response to environmental stimuli. Auxin response factors (ARFs) are transcription factors containing B3 DNA binding domain. ARFs play central role in auxin response, using Aux/IAA proteins as partners. Arachis is a genus within the Dalbergioid clade of papilionoid legumes, which out-branched from other members of papilionoids. Cultivated peanut (Arachis hypogaea L.) is an allotetraploid formed by hybridization of two parental genotypes Arachis duranensis, and Arachis ipaensis merely 10,000 years ago. We have made a genome-wide inventory of all the ARFs present in tetraploid A. hypogaea, as well as in two diploid parental genotypes. Our data show that Arachis contains more ARFs per diploid genome (around 31), compared to other legumes (around 25). We further observed few ARF-like genes which are defective in important domains. Most of the ARFs in tetraploid Arachis are redundant, representing the A and B sub-genomes. Some of the ARFs show expression bias from either A or B sub-genome, while some of the pairs are expressed from both sub-genomes. Many ARFs do not express in any of the conditions for which we have expression data. Finally, few pairs show differential spatio-temporal expression pattern from A and B sub-genomes, indicative of diversification of function. This is the first effort to list all the ARFs from an allotetraploid legume. The list of ARFs in all three species of Arachis will help the scientific community working to understand auxin regulation in crop legumes.
... However, different ploidy levels impose a barrier for direct gene transfer. While the common peanut has 2n=4x=40 chromosomes, most wild species of the taxonomic section Arachis are diploid, with 2n=2x=20 or 2n=2x=18 (Fernández et Krapovickas, 1994;Lavia et al., 2009). The section Arachis includes at least six distinct genomes, A (Robledo et al., 2009), D (Stalker, 1991;Robledo et Seijo, 2008), B, F, K (Robledo et Seijo, 2010), and G (Silvestri et al., 2015), considering the distribution patterns of both heterochromatic bands and rDNA loci. ...
... Seven accessions of A. hoehnei are available in the Embrapa Wild Arachis Genebank, all from the state of Mato Grosso do Sul, Brazil. But they are not uniform, showing differences in their reproductive cycle and crossing behavior, and doubts still persist about the presence or absence of the A chromosome pair in distinct accessions of the species (Fernández et Krapovickas, 1994;Custodio et al., 2013). ...
p>Estudios de compatibilidad cruzada en Arachis L. han sacado a la luz posibles
nuevas fuentes de genes para introgresión en el maní cultivado. Se hicieron un total de 32
cruzamientos distintos, utilizando A. gregoryi C.E. Simpson, Krapov. & Valls accesión V14957
como progenitor femenino y especies de Arachis que contienen siete genomas distintos
como progenitores masculinos. Las 3167 polinizaciones resultaron en 153 híbridos inter e
intraespecíficos confirmados. Estimaciones de viabilidad del polen paternal por tinción (PVS)
variaron de 46.75 a 99.17%, mientras que el recuento de polen de los híbridos varió de 0.30
a 43.60 %, ese PVS más alto resultando de una combinación intraespecífica, lo que sugiere
variabilidad apreciable entre accesiones de A. gregoryi. Las estimaciones de viabilidad del
polen paterno por germinación (PVG) resultaron en valores consistentemente más bajos para
todos los materiales, que van desde 41.91% a los 88.00%. Arachis gregoryi es importante para
expandir la diversidad disponible de especies asociadas con el genoma B del maní; tiene el
potencial de incorporarse como progenitor en cruzamientos que apuntan a la expansión de la base genética del maní y puede ser útil para concentrar genes importantes en líneas de pre-mejoramento asociadas al genoma B.</p
... Seeds were germinated for 5 days at 25°C, then plantlets were transferred to pots with soil and maintained in an open plan greenhouse at Embrapa Genetic Resources and Biotechnology, Brasília, DF, Brazil. After four weeks, root tips (5-10 mm long) were isolated from five plants, for each genotype and treated with 2 mM 8-hydroxyquinoline for 3 h at room temperature (Fernández and Krapovickas, 1994). Samples were incubated in a fixative solution containing absolute ethanol: glacial acetic acid (3:1, v/v) for 12 h at 4°C. ...
Peanut is a crop of the Kayabi tribe, inhabiting the Xingu Indigenous Park, Brazil. Morphological analysis of Xingu accessions showed variation exceeding that described for cultivated peanuts. This raised questions as to the origin of the Xingu accessions: are they derived from different species, or is their diversity a result of different evolutionary and selection processes? To answer these questions, cytogenetic and genotyping analyses were conducted. The karyotypes of Xingu accessions analyzed are very similar to each other, to an A. hypogaea subsp. fastigiata accession and to the wild allotetraploid A. monticola. The accessions share the number and general morphology of the chromosomes; DAPI+ bands; 5S and 45S rDNA loci distribution and a high genomic affinity with A. duranensis and A. ipaënsis genomic probes. However, the number of CMA3+ bands differs from those determined for A. hypogaea and A. monticola, which are also different from each other. SNP genotyping grouped all Arachis allotetraploids into four taxonomic groups: Xingu accessions were closer to A. monticola and A. hypogaea subsp. hypogaea. Our data suggests that the morphological diversity within these accessions is not associated with a different origin and can be attributed to morphological plasticity and different selection by the Indian tribes.
