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1.
Amplified fragment length polymorphisms (AFLPs) were used to evaluate genetic relationships within cowpea [Vigna unguiculata (L.) Walp.] and to assess the organization of its genetic diversity. Nei’s genetic distances were estimated for a total of 117 accessions including 47 domesticated cowpea (ssp. unguiculata var. unguiculata), 52 wild and weedy annuals (ssp. unguiculata var. spontanea), as well as 18 perennial accessions of the wild subspecies pubescens, tenuis and alba. AFLP variation was also used to study genetic variation among and within domesticated and wild accessions based on their geographical origin (western, eastern and southern Africa). Wild annual cowpea (var. spontanea) (H T =0.175) was more diverse than domesticated cowpea (H T =0.108). Wild cowpea was more diverse in eastern (H S =0.168) than in western Africa (H S =0.129), suggesting an eastern African origin for the wild taxon. The AFLP data were consistent with earlier findings of a unique domestication event in cowpea in the northern part of the continent and suggested that domestication in eastern or southern Africa was unlikely. It did not allow a more precise localization of domestication due to extensive gene flow between wild and domesticated forms that has led to a large crop-weed complex distributed over the entire African continent. In addition, wild materials from northeastern Africa are still lacking. Overall, the superiority of the AFLP technique over isozymes resided in its ability to uncover variation both within domesticated and wild cowpea, and should be a powerful tool once additional wild material becomes available. Received: 11 September 2000 / Accepted: 14 June 2001  相似文献   

2.
Twenty-one independent chloroplast DNA polymorphisms were identified in Vigna unguiculata defining 19 different chloroplast DNA molecules (plastome types). Two plastome types, differing by a single character, were found among 32 accessions of cultivated cowpea (Vigna unguiculata ssp. unguiculata). Eighteen different plastome types were found among 26 accessions of wild cowpea (V. unguiculata ssp. dekindtiana). The very low level of chloroplast DNA diversity found in cultivated accessions relative to wild cowpea suggests that 1) the domesticated form was derived from a narrow selection of the wild germplasm and 2) chloroplast gene flow between wild and cultivated types has been very limited. Cladistic analysis of the cpDNA data generated a robust tree completely lacking homoplasy. Three wild accessions from Nigeria possessed a plastome type indistinguishable from one present in cultivated accessions, suggesting that Nigeria represents one center of domestication of the cowpea. The other plastome type within the cultivated germplasm was not found among wild accessions.  相似文献   

3.
In 1992, Vaillancourt and Weeden discovered a very important mutation for studying cowpea evolution and domestication. A loss of a BamHI restriction site in chloroplast DNA characterized all domesticated accessions and a few wild (Vigna unguiculata ssp. unguiculata var. spontanea) accessions. In order to screen a larger number of accessions, primers were designed to check this mutation using PCR RFLP or direct PCR methods. Using these new primers, 54 domesticated cowpea accessions and 130 accessions from the wild progenitor were screened. The absence of haplotype 0 was confirmed within domesticated accessions, including primitive landraces from cultivar-groups Biflora and Textilis, suggesting that this mutation occurred prior to domestication. However, 40 var. spontanea accessions distributed from Senegal to Tanzania and South Africa showed haplotype 1. Whereas this marker could not be used to identify a precise center of origin, it did highlight the widely distributed cowpea crop-weed complex. Its very high frequency in West Africa could be interpreted as a result of either genetic swamping of the wild/weedy gene pool by the domesticated cowpea gene pool or as the result of domestication by ethnic groups focusing primarily on cowpea as fodder.  相似文献   

4.

Cowpea (Vigna unguiculata (L.)) is an important crop for food security in Senegal; therefore, understanding the genetic diversity of local germplasm is relevant for crop improvement and genetic maintenance in the era of climate change. For this purpose, 15 microsatellite markers were used to estimate the genetic diversity of Senegalese cowpea germplasm, including 671 accessions grown in eight regions and 66 wild relatives and intermediate forms (weedy). For the cultivated, the main expected heterozygosity (mHe) ranged between 0.317 (Fatick) and 0.439 (South). A narrow genetic variation between accessions from the different regions was observed with genetic similarity ranging from 0.861 to 0.965 and genetic differentiation indices (Fst) between 0.018 and 0.100. The accessions from southern Senegal (Kédougou, Sédhiou, and Kolda regions) are more diverse than the others. However, the accessions from the North (Saint-Louis) are genetically different from other regions. The diversity analysis in wild relatives from Senegal, which had never been performed before, revealed that the wild/weedy forms remain more diverse than the cultivated with genetic diversity values (He) of 0.389 and 0.480, respectively. STRUCTURE software divided the Senegalese germplasm into five subpopulations. Three of them (i, ii, and iii) included only cultivated accessions from several regions, one (v) mainly from Saint-Louis, and one (iv) the wild/weedy with some cultivated accessions. Our results support the hypothesis that Vigna unguiculata var. spontanea is the wild progenitor of cowpea. The accessions from the South, the northern recession accessions, and the wild/weedy could serve as sources of new genes for the genetic improvement of cowpea in Senegal.

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5.
One hundred and six accessions of wild barley collected from Tibet, China, including 50 entries of the two-rowed wild barley Hordeum vulgare ssp. spontaneum (HS), 29 entries of the six-rowed wild barley Hordeum vulgare ssp. agriocrithon (HA), and 27 entries of the six-rowed wild barley Hordeum vulgare ssp. agriocrithon var. lagunculiforme (HL), were analyzed using 30 SSR markers selected from the seven barley linkage groups for studying genetic diversity and evolutionary relationship of the three subspecies of Tibetan wild barley to cultivated barley in China. Over the 30 genetic loci that were studied, 229 alleles were identified among the 106 accessions, of which 70 were common alleles. H. vulgare ssp. spontaneum possesses about thrice more private alleles (2.83 alleles/locus) than HS (0.93 alleles/locus), whereas almost no private alleles were detected in HL. The genetic diversity among-subspecies is much higher than that within-subspecies. Generally, the genetic diversity among the three subspecies is of the order HS > HL > HA. Phylogenetic analysis of the 106 accessions showed that all the accessions of HS and HA was clustered in their own groups, whereas the 27 accessions of HL were separated into two groups (14 entries with group HS and the rest with group HA). This indicated that HL was an intermediate form between HS and HA. Based on this study and previous works, we suggested that Chinese cultivated barley might evolve from HS via HL to HA.  相似文献   

6.
The genus Beta L. is a morphologically and genetically variable group composed of wild, weedy, and domesticated forms that are used for sugar production or as vegetables. In this study, we have evaluated genetic variation in 64 germplasm accessions of wild and domesticated beets and examined the origin of wild beet accessions in California using allozyme analysis. UPGMA analysis showed overall that domesticated and wild beets form genetically coherent groups. Wild beets in California have two different origins, from European Beta vulgaris or from Beta macrocarpa. Population-level patterns of allozyme variation for wild California beets related to B. vulgaris suggest that those populations evolved from naturalized populations of the cultivated B. vulgaris ssp. vulgaris which had hybridized to varying degrees with the sea beets B. vulgaris ssp. maritima. Wild California beets related to B. macrocarpa are essentially genetically identical to European accessions. In addition, we found substantial evidence for hybridization and introgression of B. vulgaris alleles in one B. macrocarpa accession in California. The obligate outcrosser B. vulgaris exhibits more allelic diversity than the self-compatible B. macrocarpa. Beta vulgaris ssp. maritima exhibits more genetic diversity than domesticated B. vulgaris ssp. vulgaris. Received: 2 November 1998 / Accepted: 29 April 1999  相似文献   

7.
Eighty-one cultivated and 55 wild accessions were characterized using one- and two-dimensional isoelectric focusing (1D and 2D IEF)/SDS-PAGE and immuno-detection techniques to examine genetic diversity present within cultivated and wild taxa inVigna unguiculata (L.) Walp. Twenty-seven unique banding patterns were identified in the vignin (or Gl) fraction of the major seed storage proteins. These patterns were controlled by at least four interacting genes, two of which were tightly linked and a third which also may be linked. Due to the tremendous amount of variation in these wild taxa it is not possible to make definitive statements about either the taxonomic or geographic distribution of vignin types. These results give no final answer to the identity of the progenitor of cowpea or the center of domestication, but do pose some interesting questions to be asked as the genetic relationships among the wild and cultivated taxa in this species are unraveled.  相似文献   

8.
The wild grapevine, Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi, considered as the ancestor of the cultivated grapevine, is native from Eurasia. In Spain, natural populations of V. vinifera ssp. sylvestris can still be found along river banks. In this work, we have performed a wide search of wild grapevine populations in Spain and characterized the amount and distribution of their genetic diversity using 25 nuclear SSR loci. We have also analysed the possible coexistence in the natural habitat of wild grapevines with naturalized grapevine cultivars and rootstocks. In this way, phenotypic and genetic analyses identified 19% of the collected samples as derived from cultivated genotypes, being either naturalized cultivars or hybrid genotypes derived from spontaneous crosses between wild and cultivated grapevines. The genetic diversity of wild grapevine populations was similar than that observed in the cultivated group. The molecular analysis showed that cultivated germplasm and wild germplasm are genetically divergent with low level of introgression. Using a model‐based approach implemented in the software structure , we identified four genetic groups, with two of them fundamentally represented among cultivated genotypes and two among wild accessions. The analyses of genetic relationships between wild and cultivated grapevines could suggest a genetic contribution of wild accessions from Spain to current Western cultivars.  相似文献   

9.
应用微卫星标记研究西藏野生大麦的遗传多样性   总被引:9,自引:0,他引:9  
以西藏不同地区的106份野生大麦为材料,其中包括50份野生二棱大麦(HS),27份野生瓶形大麦(HL)和29份野生六棱大麦(HA),用Liu等(1996)发表的SSR连锁图的每个连锁群的两个臂的不同位置上选取3~5个共30个SSR标记,研究了西藏3类野生大麦的遗传多样性。结果表明,这3类野生大麦在遗传组成及等位变异频率分布上存在着明显的遗传分化。在总样本中,共检测到229个等位变异,平均每个SSR位点检测到7.6个等位变异,其中70个为这3类野生大麦间共同的等位变异,等位变异数在这3类野生大麦间有明显的差异,亚种问的遗传多样性明显高于亚种内的遗传多样性。其遗传多样性大小顺序为HS〉HL〉HA。聚类分析表明,野生二棱大麦、野生六棱大麦分别聚在不同的两类,而野生瓶形大麦中各有约50%的材料分别聚在这两类。根据本研究及前人研究结果,我们认为中国栽培大麦是从野生二棱大麦经野生瓶形大麦向野生六棱大麦进化的。该结果支持了栽培大麦起源的“野生二棱大麦单系起源论”的观点。  相似文献   

10.
Asparagus bean (V. unguiculata ssp. sesquipedialis), a specific form of cowpea (V. unguiculata L. Walp.), is cultivated as a vegetable crop throughout eastern and southern Asia for its tender long pods. Little is known about the genetic relationship between asparagus bean and the broader species, particularly the dominant ssp. unguiculata. We report here the development and transferability of simple sequence repeat (SSR) markers, over 40% of which are EST-derived, from ssp. unguiculata to asparagus bean and the use of a subset of the polymorphic markers to assess the genetic diversity of asparagus bean cultivars from diverse geographic origins across China. A total of 410 EST derived SSR (eSSR) markers and 600 SSR markers derived from cowpea genespace sequences (GSS) were developed, with a cross-subspecies transferability of 100% and 98.5%, respectively. In a recombinant inbred line population of asparagus bean, a 1:1 segregation was observed for most loci. Principal coordinate analysis (PCA) and phylogenetic clustering based on 62 alleles detected by 14 polymorphic SSR markers distinguished ssp. unguiculata and sesquipedialis into separate groups. Improved asparagus bean cultivars in China generally have a narrow genetic basis compared with landraces varieties. This suggests that asparagus bean breeding programs need to consider utilizing landrace germplasm to enhance genetic variability and ensure long-term gains from selection and reduce genetic vulnerability to pathogen/pest epidemics. Because of their transferability across subspecies, the SSR markers described in this study could be effectively employed in cross-subspecies trait introgression breeding from ssp. unguiculata to sesquipedialis.  相似文献   

11.
A restriction-site analysis of chloroplast DNA (cpDNA) variation in Lens was conducted to: (1) assess the levels of variation in Lens culinaris ssp. culinaris (the domesticated lentil), (2) identify the wild progenitor of the domesticated lentil, and (3) construct a cpDNA phylogeny of the genus. We analyzed 399 restriction sites in 114 cultivated accessions and 11 wild accessions. All but three accessions of the cultivar had identical cpDNAs. Two accessions exhibited a single shared restriction-site loss, and a small insertion was observed in the cpDNA of a third accession. We detected 19 restriction-site mutations and two length mutations among accessions of the wild taxa. Three of the four accessions of L. culinaris ssp. orientalis were identical to the cultivars at every restriction site, clearly identifying ssp. orientalis as the progenitor of the cultivated lentil. Because of its limited cpDNA diversity, we conclude that either the cultivated lentil has passed through a genetic bottleneck during domestication and lost most of its cytoplasmic variability or else was domesticated from an ancestor that was naturally depauperate in cpDNA restriction-site variation. However, because we had access to only a small number of populations of the wild taxa, the levels of variation present in ssp. orientalis can only be estimated, and the extent of such a domestication bottleneck, if applicable, cannot be evaluated. The cpDNA-based phylogeny portrays Lens as quite distinct from its putative closest relative, Vicia montbretii. L. culinaris ssp. odemensis is the sister of L. nigricans; L. culinaris is therefore paraphyletic given the current taxonomic placement of ssp. odemensis. Lens nigricans ssp. nigricans is by far the most divergent taxon of the genus, exhibiting ten autapomorphic restriction-site mutations.  相似文献   

12.
Relationships among cultivated and wild lentils revealed by RAPD analysis   总被引:5,自引:0,他引:5  
RAPD markers were used to distinguish between six different Lens taxa, representing cultivated lentil and its wild relatives. Twenty-four arbitrary sequence 10-mer primers were identified which revealed robust and easily interpretable amplification-product profiles. These generated a total of 88 polymorphic bands in 54 accessions and were used to partition variation within and among Lens taxa. The data showed that, of the taxa examined, ssp. orientalis is most similar to cultivated lentil. L. ervoides was the most divergent wild taxon followed by L. nigricans. The genetic similarity between the latter two species was of the same magnitude as between ssp. orientalis and cultivated lentil. In addition, species-diagnostic amplification products specific to L. odemensis, L. ervoides and L. nigricans were identified. These results correspond well with previous isozyme and RFLP studies. RAPDs, however, appear to provide a greater degree of resolution at a sub-species level. The level of variation detected within cultivated lentils suggests that RAPD markers may be an appropriate technology for the construction of genetic linkage maps between closely related Lens accessions.On sabbatical leave from HP Agricultural University, Palampur 176 062, India  相似文献   

13.
An electrophoretic comparison of variation at 37 presumptive isozyme gene loci was performed for 55 wildVigna unguiculata accessions. The analysis included seven subspecies, covering the whole range of variation available in wildVigna unguiculata. The results of the isoenzymatic study broadly confirmed the previous infraspecific classification inferred from morphological data. Although the southern taxa (e.g., subsp.tenuis, subsp.stenophylla) are as yet too poorly sampled to discuss in depth, wildVigna unguiculata can be divided into one mainly autogamous annual group (including subsp.pubescens and var.spontanea) and several widely divergent perennial subspecies.  相似文献   

14.
Intensive greenhouse screening using potted plants demonstrated a high level of resistance in the wild cowpea, Vigna unguiculata (ssp. mensensis), to the cowpea moth, Cydia ptychora. Two closely related cvs (TVu 946 and TVu 2994) also showed some resistance. Further investigations in the laboratory and in the greenhouse indicated that resistance was due mainly to oviposition preference and to antibiosis. Pods of the wild cowpea, and those of cvs TVu 946 and TVu 2994, were not attractive to egg-laying females whereas no oviposition preference was seen among the genetically improved cultivars. Pronounced antibiosis was detected in the wild cowpea, and to a lesser extent in the closely related cvs, when pods were infested with first-instar larvae. Fecundity of females was also significantly reduced. These effects were thought to be partly due to nutritional deficiencies in the resistant cvs but there may also be an antibiotic factor in the wild cowpea progenitor. Apparently, pod-wall thickness was not related to resistance although differences in successful penetration of pods by larvae were observed.  相似文献   

15.
A compromise classification of the genus Zea, reflecting both phylogeny and practical needs, recognizes six taxa, as follows: Section Luxuriantes : Zea perennis. Zea diploperennis, Zea luxurians. Section Zea : Zea mays ssp. mexicana (Neo-volcanic Plateau), Zea mays ssp. parviglumis Iltis & Doebley ssp. n. var. parviglumis (Rio Balsas drainage, Pacific slope from Guerrero to Jalisco), Zea mexicana ssp. parviglumis var. huehuetenangensis Iltis & Doebley var. n. (Pacific slope, western Guatemala, Prov. Huehuetenango), Zea mays ssp. mays. The new subspecies is distinguished by smaller spikelets and rachis joints, the varieties by different habitats, blooming dates and their genetic behavior in relation to cultivated Zea mays. Zea mays ssp. mexicana is the ancestor of corn.  相似文献   

16.
Levels of seed proteins in Citrullus and Praecitrullus accessions   总被引:1,自引:0,他引:1  
Variation among 17 accessions of Citrullus lanatus from different geographic regions and interspecific relationships of six taxa of Citrullus and Praecitrullus were studied using electrophoretic patterns of their seed storage proteins. Globulins, the salt soluble proteins, represented the major fraction with their proportion varying between 56.6% and 67.0%. These were followed by albumins (16.6–20.8%) and glutelins (13.5–18.5%) with prolamins as the lowest (2.2–4.1%) of the four fractions. Two-dimensional gel electrophoresis under nonreducing conditions in the first dimension and reducing conditions in the second revealed disulphide-bonded subunit pairs of molecular weight 53, 52, 50 and 41 kDa, unlike the single subunit pair generally reported in different cucurbits, each consisting of a large and a small subunit. In the UPGMA dendrogram based on polypeptide patterns, the occurrence of C. lanatus var. lanatus, C. lanatus var. citroides and C. lanatus accession PI 482318 in one subcluster suggested that phylogenetically C. lanatus var. citroides and C. lanatus var. lanatus are closely related. The recently described annual wild species, Citrullus rehmii, occurred independently nearest to the subcluster of these cultivated and wild taxa. Citrullus colocynthis, the perennial wild species occurred farther from this cluster showing relatively more genetic distance from the watermelons. Praecitrullus fistulosus was outclustered and appeared genetically distant from all the Citrullus taxa; this supported its placement in a separate genus unlike its nomenclature as a botanical variety of watermelon or as a separate species of Citrullus proposed in certain earlier studies.  相似文献   

17.
Summary Fifty-six accessions of cultivated and wild sorghum were surveyed for genetic diversity using 50 low-copy-number nuclear DNA sequence probes to detect restriction fragment length polymorphisms (RFLPs). These probes revealed greater genetic diversity in wild sorghum than in cultivated sorghum, including a larger number of alleles per locus and a greater portion of polymorphic loci in wild sorghum. In comparison to previously published isozyme analyses of the same accessions, RFLP analysis reveals a greater number of alleles per locus. Furthermore, many RFLP alleles have frequencies between 0.25–0.75, while the vast majority of isozyme alleles are either rare (< 0.25) or near fixation (> 0.75). Correlations between genetic and geographic distances among the accessions were stronger when calculated with RFLP than with isozyme data. Systematic relationships revealed by nuclear and chloroplast restriction site analysis indicate that cultivated sorghum is derived from the wild ssp. arundinaceum. The portion of the wild gene pool most genetically similar to the cultivars is from central-northeastern Africa. Previous published data also suggested that this is most likely the principal area of domestication of sorghum. Introgression between wild and cultivated sorghum was inferred from disconcordant relationships shown by nuclear and chloroplast DNA markers. Introgression apparently occurs infrequently enough that the crop and its wild relatives maintain distinct genetic constitutions.  相似文献   

18.
Sixty-two single-copy sorghum DNA clones were used to compare restriction fragment patterns of 53 sorghum accessions from Africa, Asia and the United States. Included were accessions from five morphological races of the cultivated subspecies bicolor, and four races of the wild subspecies verticilliflorum. From two to twelve alleles were detected with each probe. There was greater nuclear diversity in the wild subspecies (255 alleles in ten accessions) than in the domestic accessions (236 alleles in 37 accessions). Overall, 204 of the 340 alleles (60%) that were detected occurred in both subspecies. Phylogenetic analysis using parsimony separated the subspecies into separate clusters, with one group of intermediate accessions. Though exceptions were common, especially for the race bicolor, accessions classified as the same morphological race tended to group together on the basis of RFLP similarities. Selection for traits such as forage quality may have led to accessions genetically more similar to other races being classified as bicolors, which have a loose, small-grained panicle similar to wild races. Population statistics, calculated using four nuclear and four cytoplasmic probes that detect two alleles each, revealed a low but significant amount of heterozygosity, and showed little differentiation in alleles in the wild and cultivated subspecies. Outcrossing with foreign pollen appears to have been more important than migration via seed dispersal as a mechanism for gene flow between the wild and domestic accessions included in this study.  相似文献   

19.
Summary Thirty accessions of domesticated (Lens culinaris ssp. culinaris) and wild (L. culinaris ssp. orientalis, L. culinaris ssp. odemensis, L. nigricans ssp. ervoides and L. nigricans ssp. nigricans) lentil were evaluated for restriction fragment length polymorphisms (RFLPs) using ten relative low-copy-number probes selected from partial genomic and cDNA libraries of lentil. Nei's average gene diversity was used as a measure of genetic variability for restriction fragment lengths within subspecies and a dendrogram was constructed from genetic distance estimates between subspecies. The wild lentils L. culinaris ssp. orientalis and L. culinaris ssp. odemensis showed the greatest variability for restriction fragment lengths and were closely positioned to domesticated lentil in the dendrogram. Little variability for restriction fragment lengths was observed within accessions of L. nigricans ssp. ervoides and L. nigricans ssp. nigricans. This observation is consistent with a previously published proposal that nigricans may have been independently domesticated. Estimates of genetic variability based on RFLPs tended to be greater than estimates from isozymes.  相似文献   

20.
Broadening of the genetic base and systematic exploitation of heterosis in cultivated lentils requires reliable information on genetic diversity in the germplasm. The ability of random amplified polymorphic DNA (RAPD) to distinguish among different taxa of Lens was evaluated for several geographically dispersed accessions/cultivars of four diploid Lens species. This study was carried out to assess whether RAPD data can provide additional evidence about the origin of the cultivated lentil and to measure genetic variability in lentil germplasm. Three cultivars of Lens culinaris ssp. culinaris, including one microsperma, and two macrosperma types, and four wild species (L. culinaris ssp. orientalis, L. odemensis and L. nigricans) were evaluated for genetic variability using a set of 1 11-mer and 14 random 10-mer primers. One hundred and fifty-eight reproducible and scorable DNA bands were observed from these primers. Genetic distances between each of the accessions were calculated from simple matching coefficients. Split decomposition analysis of the RAPD data allowed construction of an unrooted tree. This study revealed that (1) the level of intraspecific genetic variation in cultivated lentils is narrower than that in some wild species. (2) L. culinaris ssp. orientalis is the most likely candidate as a progenitor of the cultivated species, (3) L. nigricans accession W6 3222 (unknown) and L. c. ssp. orientalis W6 3244 (Turkey) can be reclassified as species of L. odemensis and (4) transmission of genetic material in Lens interspecific hybrids is genotypically specific, as identified by the RAPD markers in our study.  相似文献   

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