Fig 1 - uploaded by Zulfi Jahufer
Content may be subject to copyright.
Somatic and meiotic chromosome configurations in F 1 and BC 1 hybrids: (A) An F 1 cell (2n = 4x = 32) at late metaphase with three satellited chromosomes (arrows), (B) a BC 1 cell (2n = 4x = 32) at late metaphase with three satellited chromosomes (arrows), (C) F 1 with two univalents, seven bivalents, and four quadrivalents at metaphase I, (D) BC 1 with two univalents, nine bivalents, and four quadrivalents at metaphase I, (E) F 1 with 16-16 chromosome disjunction at anaphase I, and (F) BC 1 with 16-16 chromosome disjunction at anaphase I.
Source publication
A significant constraint to the vegetative persistence of white clover (Trifolium repens L.) is summer moisture stress. A closely related species, T. uniflorum L., has a robust root system that could provide drought resistance. Hybridization of these two species leads to the generation of fertile hybrids. A study was conducted to generate F1 hybrid...
Context in source publication
Context 1
... F 1 and five BC 1 plants were evaluated for somatic chro- mosome counts (Table 5) and were all tetraploid (2n = 4x = 32). Hybridity of the F 1 plants was confirmed by the pres- ence of three satellited chromosomes ( Fig. 1), two derived from the T. uniflorum male parent and one from the T. repens female parent. Meiotic chromosome configurations of the five F 1 and five BC 1 plants consistently revealed both triva- lent and quadrivalent formation (Table 5), indicating close chromosome pairing homology between the genomes of the two species. The pollen fertility of the hybrid plants was negatively correlated with the frequency of odd-numbered configurations (univalents and trivalents, r = −0.85, P < 0.01). Mean frequencies of univalent and trivalent configu- rations for the F 1 and BC 1 did not differ, and mean pollen staining was similar (62-63%) for both generations. Mean Table 4. Pollen staining of the BC 1 families derived from three F 1 ...
Similar publications
Background:
Trifolium ambiguum occurs as a 2x, 4x, 6x polyploid series in W Asia. The 6x form is the most agronomically desirable, having strong rhizomatous spread and drought tolerance. These traits would be potentially very valuable if they could be transferred to white clover (T. repens) which is the most important agronomic clover species. How...
Citations
... In New Zealand, breeding efforts of hybridisation of white clover and Trifolium uniflorum, which has a thicker taproot, have focussed on increasing the taproot diameter and structure to elongate the lifespan of the seminal taproot (Hussain et al., 2017;Nichols et al., 2015;Nichols et al., 2016;Nichols, Hofmann, Williams, & Crush, 2014). In this work, a hybrid of white clover with T. uniflorum showed increased taproot survival but no significant difference between tap root sizes compared to white clover. ...
The expanded usage of white clover has increased the importance of understanding white clover dynamics in pastures. It is assumed that clover plants have a higher tolerance for moisture and nutrient deficiencies when the taproot is still present. Therefore, the survival of the seminal taproot can influence the dynamics of clover. Past breeding efforts in countries like New Zealand have focussed on increasing the taproot longevity through hybridisation with a close relative of white clover. However, there is no direct evidence whether increased survival of the taproot results in increased performance of white clover. In this study, we aimed to (i) assess the relationship between taproot volume and taproot survival, and (ii) whether the timing of death of the seminal taproot influences the population dynamics of white clover varieties. In a two‐year field experiment with 18 white clover varieties grown in monoculture and in mixture with Lolium perenne L, the taproot characteristics and population dynamics were studied. It was shown that taproot volume was positively correlated to both leaf size and taproot presence during autumn 2017, 1 year after sowing. The combination of the timing of death of the seminal tap root and the development of stolons seems to play a more important role in increasing the persistence of white clover than the absolute survival of the seminal taproot. Future research should focus on understanding the transition from a taprooted white clover to a stolonous white clover plant in relation to specific weather events such as winter frost conditions.
... The R sub-genomes (P r and O r ) never pair at meiosis in white clover, probably because of a genetic system preventing homoeologous pairing (Williams, 2014). However, they do pair in interspecific hybrids, as shown in 4x T. repens × T. uniflorum and 4x T. repens × T. occidentale hybrids (Hussain et al., , 2017. Probably they could also pair with each other in the P r O r AO hybrids, leading to novel P r -O r recombination. ...
Many crop gene pools are derived from a small number of founders. As a consequence of long histories of strong directional selection, crop gene pools have narrow genetic diversity available to provide inherent solutions to changing needs or challenges. Notoriously, plants can mate across taxonomically-determined species boundaries, and interspecific hybridization is widely used in plant genetics research. Interspecific hybridizations have conferred practical improvements to crops, some of which are unexpected based on the phenotypes of the parents.
Genomics has provided insights into the fundamental consequences of interspecific hybridization for plant biology. Additionally, genomics has allowed the development of molecular tools for dissecting the genetic control of phenotypic variation in interspecific hybrid populations and manipulating interspecific introgressions in crop improvement.
This Research Topic aims to publish peer-reviewed research to interspecific hybridization and its consequences, both fundamental and applied. While such work is prominent in plants, consideration will also be given to salient work in other taxa. A key threshold for publication will be the extent to which findings are of cross-cutting interest and importance, i.e. not only to those working on the target taxon but to a wide range of biological scientists.
... The R sub-genomes (P r and O r ) never pair at meiosis in white clover, probably because of a genetic system preventing homoeologous pairing (Williams, 2014). However, they do pair in interspecific hybrids, as shown in 4x T. repens × T. uniflorum and 4x T. repens × T. occidentale hybrids (Hussain et al., , 2017. Probably they could also pair with each other in the P r O r AO hybrids, leading to novel P r -O r recombination. ...
White clover (Trifolium repens) is an allotetraploid pasture legume widely used in moist temperate climates, but its vulnerability to drought, grazing pressure and pests has restricted its wider use. A related species, Caucasian clover (Trifolium ambiguum), is a potential source of resistances to drought, cold, grazing pressure and pests that could potentially be transferred to white clover by interspecific hybridization. Although direct hybridization has been achieved with difficulty, the hybrids have not been easy to backcross for introgression breeding and no interspecific chromosome recombination has been demonstrated. The present work shows that interspecific recombination can be achieved by using Trifolium occidentale, one of the ancestral parents of T. repens, as a bridging species and that large white clover breeding populations carrying recombinant chromosomes can be generated. A 4x hybrid between T. ambiguum and T. occidentale was crossed with T. repens and then backcrossed for two generations. Five backcross hybrid plants with phenotypes appearing to combine traits from the parent species were selected for FISH-GISH analyses. Recombinant chromosome segments from T. ambiguum were found in all five plants, suggesting that recombination frequencies were significant and sufficient for introgression breeding. Despite early chromosome imbalances, the backcross populations were fertile and produced large numbers of seeds. These hybrids represent a major new resource for the breeding of novel resilient forms of white clover.
... The three species that have been popularly bred as hybrids are Trifolium uniflorum, Trifolium occidentale and Trifolium ambiguum. Trifolium uniflorum have been successful in breeding programmes and have shown promising results in producing hybrids that have increased performance under drought tolerance and reduced phosphate levels [44,[68][69][70][71]. ...
Background:
Prebreeding in plants is the activity designed to identify useful characteristics from wild germplasm and its integration in breeding programs. Prebreeding aims to introduce new variation into the populations of a species of interest. Pedigree analysis is a valuable tool for evaluation of variation in genebanks where pedigree maps are used to visualize and describe population structure and variation within these populations. Margot Forde Germplasm Centre (MFGC) is New Zealand's national forage genebank and holds a collection of ~ 75 species of the genus Trifolium, of which only a dozen have been taken through prebreeding programs. The main objective of this study was to construct pedigree maps and analyse patterns of relatedness for seven minor Trifolium species accessions contained at the MFGC. These species are Trifolium ambiguum, Trifolium arvense, Trifolium dubium, Trifolium hybridum, Trifolium medium, Trifolium subterraneum and the Trifolium repens x Trifolium occidentale interspecific hybrids. We present a history of Trifolium spp. prebreeding in New Zealand and inform breeders of possible alternative forage species to use.
Results:
Pedigree data from accessions introduced between 1950 and 2016 were used and filtered based on breeding activity. Kinship levels among Trifolium spp. remained below 8% and no inbreeding was found. Influential ancestors that contributed largely to populations structure were identified. The Australian cultivar 'Monaro' had a strong influence over the whole population of accessions in T. ambiguum. T. subterraneum and T. repens x T. occidentale had the largest number of generations (3). T. ambiguum and T. medium had the highest cumulative kinship across the decades.
Conclusions:
We conclude that there are high levels of diversity in the seven Trifolium spp. studied. However, collection and prebreeding efforts must be strengthened to maximize utilization and bring useful genetic variation.
... However, some potential genes have been identified to be involved in flower pigmentation and other chemical characteristics of white clover [22][23][24]. Hybrid varieties have been developed with enhanced physicochemical and biological potential, especially from T. repens and Trifolium uniflorum [25]. However, genotypic and phenotypic diversity does not affect productivity and drought response in competitive stands of T. repens [26]. ...
Trifolium repens belongs to the family Leguminosae and has been used for therapeutic purposes as traditional medicine. The plant is widely used as fodder and leafy vegetables for human uses. However, there is a lack of a detailed review of its phytochemical profile and pharmacological properties. This review presents a comprehensive overview of the phytochemical profile and biological properties of T. repens. The plant is used as antioxidants and cholinesterase inhibitors and for anti-inflammatory, antiseptic, analgesic, antirheumatic ache, and antimicrobial purposes. This review has summarized the available updated useful information about the different bioactive compounds such as simple phenols, phenolic acids, flavones, flavonols, isoflavones, pterocarpans, cyanogenic glucosides, saponins, and condensed tannins present in T. repens. The pharmacological roles of these secondary metabolites present in T. repens have been presented. It has been revealed that T. repens contain important phytochemicals, which is the potential source of health-beneficial bioactive components for food and nutraceuticals industries.
Clover which is an herbaceous, annual, and self-pollinated plant belongs to fabaceae family (legumes) and has become naturalized in Iran, Asia Minor and the Mediterranean eastern suburban countries. The aim of the present study is ITS molecular evaluation of the nuclear ribosomal genes of lines and landraces of Persian Clover. The sequences were aligned using ClustalW method and by MegAlign software and the dendrogram of different phylogenetic and matrix relationships between the sequences were drawn. The results showed little genetic diversity between the lines and the landrace. The conserved sequence of the analyzed gene in the Persian clover is 561 base. Totally, 740 loci (69 and 671 loci, respectively, with and without removal and addition), 9 Singletons, and 5 haplotypes were identified. The highest rate of transfer was observed in pyrimidine (%16.3). The numerical value of the ratio (dN/dS) was 0.86, and since it was less than 1, the pure selection on the studied gene happened. The lines and landraces were not separated based on their geographic locations. In general, the results indicated that the highest rate of the regional diversity belonged to the clover plants in Lorestan region. Moreover, ITS markers did not seem suitable enough for evaluating the intra-species genetic variation, but it was quite well-suited for inter-species or intergeneric evaluation.
