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1.
Twenty maize landrace accessions regenerated and conserved in five maize genebanks were investigated for genetic integrity using 1,150 Single Nucleotide Polymorphisms (SNPs) and 235 SNP haplotypes. The genetic diversity of three accessions changed significantly in terms of the average number of alleles per locus. Ten out of twenty accessions had significantly different SNP allelic frequencies, either after regeneration or in the same accession held in different genebanks. The proportion of loci with significant changes in SNP allelic frequency was very low (37/1,150). Changes in the major allelic frequency (MAF) for the majority of SNP loci (60.2–75.2%) were less than 0.05. For SNP haplotypes, the genetic diversity of four accessions changed significantly in terms of average number of haplotype alleles and polymorphic information content (PIC) per locus. The proportion of SNP haplotype alleles lost in the later generations ranged between 0 and 22.6%, and at the same time 0–19.9% of the SNP haplotype alleles appeared in later generations, however, these were absent in the earlier generations. Dynamic changes in genetic integrity, in terms of presence and absence of genes (alleles), by both SNP and SNP haplotype analysis were detected during regeneration. A suboptimum number of ears harvested in one generation can be combined with those from another, repeated regeneration to capture the diversity of the previous generation. Use of molecular markers during regeneration of accessions can help in understanding the extent of genetic integrity of the maize accessions in ex situ genebanks and in recommending the best practice for maintaining the original genetic diversity of the genebank accessions.  相似文献   

2.
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3.
The origin of cultivated potatoes has remaining questions. In this study, 237 accessions of all cultivated species and 155 accessions of wild species closely related to cultivated potatoes, including their putative ancestors, were analyzed using 15 plastid microsatellites (SSRs) to investigate genetic diversity and their relationships with the wild species. We here used polymorphic plastid SSRs we developed from potato plastid genome sequences as well as already known plastid SSR markers. All 15 loci were polymorphic and identified a total of 127 haplotypes. Dramatic decreases in levels of genetic diversity were revealed in landraces in comparison with wild ancestor species. The plastid SSR results showed a decrease in haplotype number and diversity from Peru to both north and south. Phylogenetic analysis revealed two distinct groups. One of them, group A, contained the majority of accessions of cultivated species of the Solanum tuberosum Andigenum group including all accessions of cultivated diploid and triploid cytotypes of this group (S. chaucha, S. phureja, and S. stenotomum by a former taxonomic system) and most of tetraploid accessions of the S. tuberosum Andigenum group (S. tuberosum subsp. andigenum), and the majority of accessions of wild ancestors from the northern members of the S. brevicaule complex. Another group B comprised most of the wild species accessions and almost exclusively hybrid cultivated species which have introgressed plastid genomes from the other wild gene pools. Lack of clustering of traditional cultivated species (as used above) support a revised group classification of S. tuberosum.  相似文献   

4.
Genetic variation within and among several Sorghum populations from different agroecological zones in Malawi were investigated using random amplified polymorphic markers (RAPDs). DNA samples from individual plants were analyzed using 35 oligonucleotides of random sequence. Twenty five of these primers allowed amplifications of random polymorphic (RAPD) loci. Overall, 52% of the scored loci were polymorphic. Every accession was genetically distinct. The analysis of molecular variance revealed that the within-region (among accessions) variations accounted for 96.43% of the total molecular variance. Observed variations in allelic frequency was not related to agroecological differences. The degree of band sharing was used to evaluate genetic distance between accessions and to construct a phylogenetic tree. Further analysis revealed that the sorghum accessions analyzed were genetically close despite considerable phenotypic diversity within and among them. It is suggested that all the sorghum landraces currently available in Malawi should be conserved both ex situ and in situ to maintain the current level of genetic diversity.  相似文献   

5.
A total of 8117 suitable SSR-contaning ESTs were acquired by screening from a Malus EST database, among which dinudeotide SSRs were the most abundant repeat motif, within which, CT/TC followed by AG/GA were predominant. Based on the suitable sequences, we developed 147 SSR primer pairs, of which 94 pairs gave amplifications within the expected size range while 65 pairs were found to be polymorphic after a preliminary test. Eighteen primer pairs selected randomly were further used to assess genetic relationship among 20 Malus species or cultivars. As a result, these primers displayed high level of polymorphism with a mean of 6.94 alleles per locus and UPGMA cluster analysis grouped twenty Malus accessions into five groups at the similarity level of 0.6800 that were largely congruent to the traditional taxonomy. Subsequently, all of the 94 primer pairs were tested on four accessions of Pyrus to evaluate the transferability of the markers, and 40 of 72 functional SSRs produced polymorphic amplicons from which 8 SSR loci selected randomly were employed to analyze genetic diversity and relationship among a collection of Pyrus. The 8 primer pairs produced expected bands with the similar size in apples with an average of 7.375 alleles per locus. The observed heterozygosity of different loci ranged from 0.29 (MES96) to 0.83 (MES138), with a mean of 0.55 which is lower than 0.63 reported in genome-derived SSR marker analysis in Pyrus. The UPGMA dendrogram was similar to the previous results obtained by using RAPD and AFLP markers. Our results showed that these EST-SSR markers displayed reliable amplification and considerable polymorphism in both Malus and Pyrus, and will contribute to the knowledge of genetic study of Malus and genetically closed genera.  相似文献   

6.
For millennia, wheat (Triticum spp.) has been grown in traditional aflaj-irrigation systems of remote mountain oases in Oman. However, little is known about the diversity of the ancient landraces used. Given recent reports about the occurrence of novel germplasm in such material, the objective of this study was to evaluate the genetic diversity of hexaploid wheat (Triticum aestivum L.) landraces in relation to their geographic origin using microsatellites. The collection covered most of the cultivation areas in northern Oman where wheat landraces are growing. Total genomic DNA was extracted from six pooled plants representing each accession. A total of 161 wheat accessions were assayed using 35 microsatellite loci in which a total of 305 polymorphic bands were recorded for the 35 microsatellites. The polymorphic information content (PIC) across the 35 microsatellite loci ranged from 0.02 to 0.89 with an average of 0.50. A heterozygosity percentage value of 9.09 was determined and the highest level recorded for accessions from the Batinah district. Rare alleles averaged 1.85 with the highest value being from the Dakhilia district. The results indicated a significant correlation between gene diversity and number of alleles across districts. The correlation coefficient between these two variables over the 35 loci was 0.657, whereby correlation coefficients of 0.718, 0.706, 0.657 and 0.651, respectively, were found for the Batinah, Dhahira, Dakhilia and Sharqia materials. Genetic distances indicated that all landraces were closely related. The cluster analysis discriminated most of the landraces accessions. However, it failed to achieve region-specific groupings of landraces. The present study demonstrated the presence of high diversity in Omani landraces and also indicated the effectiveness of microsatellites to describe it.  相似文献   

7.
Diversity analysis was performed among 39 cultivated lentil (Lens culinaris Medik.) accessions of Central Asia and Caucasian origin using five highly polymorphic microsatellite markers. A total of 33 alleles determined ranging from 3 to 8 per locus. Estimated gene diversity value for 33 loci was 0.66. Genetic similarity indices among 39 accessions ranged from 0.24 to 1.0. Cluster analysis using the unweighted pair group method with arithmetic mean method classified accessions into six major groups at 0.5 similarity coefficient. More than half accessions from Tajikistan formed large cluster. On the other hand, a few accessions from each country showed unique genotypes. Overall, most of the accessions, except ones with closely related origin, were distinguished by the present high quality DNA fingerprinting. This molecular diversity information gives important basis for conservation strategy in gene bank and exotic germplasm introduction in breeding programs in Central Asia and Caucasian countries.  相似文献   

8.
Little is known about the genetic diversity of pale flax (Linum bienne Mill.), the wild progenitor of cultivated flax (L. usitatissimum L.), and ex situ germplasm of pale flax was scarce. Effort was made to collect 34 pale flax accessions and five landrace accessions of cultivated flax in Turkey. The inter simple sequence repeat (ISSR) technique was applied to characterize this set of flax germplasm, along with one Turkish cultivar, one Russian cultivar, five winter and four dehiscent type accessions of cultivated flax. Twenty-four ISSR primer pairs detected a total of 311 DNA fragments, of which 298 bands were polymorphic across 493 flax samples (roughly 10 samples per accession). These polymorphic bands had frequencies ranging from 0.002 to 0.998 and averaging 0.38. Accession-specific ISSR variation (Fst values) ranged from 0.469 to 0.514 and averaged 0.493. There was 49.3% ISSR variation resided among these 50 accessions, 35.9% harbored among landrace, winter, dehiscent types of cultivated flax and pale flax, and 38.2% present among 34 pale flax accessions. Pale flax displayed more ISSR variation than landraces and dehiscent type, but less than winter type, of cultivated flax. Clustering 493 individual plants revealed that these assayed plants were largely grouped according to their plant types and that pale flax was genetically more close to the dehiscent type, followed by the winter type and landrace, of cultivated flax. Pale flax collected within the geographic range of 180 km displayed a significant spatial genetic autocorrelation. Genetic distances among the pale flax accessions were significantly associated with their geographic distances and elevation differences. These findings are significant for understanding flax domestication and its primary gene pool.  相似文献   

9.
To assess the genetic diversity among China’s cultivated barley, sequence tagged site (STS) marker analysis was carried out to characterize 109 morphologically distinctive accessions originating from five Chinese eco-geographical zones. Fourteen polymorphic STS markers representing at least one in each chromosome were chosen for the analysis. The 14 STS markers revealed a total of 47 alleles, with an average of 3.36 alleles per locus (range 2–8). The proportion of polymorphic loci per population averaged 0.84 (range 0.71–1.00); the mean gene diversity averaged 0.39 (range 0.28–0.49). The means of P and He were highest in the Yangtze reaches and Southern zone (P = 1.00; He = 0.46) and lowest (P = 0.71 He = 0.28) in the Yellow river reaches zone. The STS diversity in different zones is quite different from the morphology diversity. The STS variation was partitioned into 17% among the zone and 83% within the zone. Both cluster and principal coordinate analyses clearly separated the accessions into a dispersed group (mostly two-rowed barley with a lower mean GS value) and a concentrated group (mostly six-rowed barley with a higher mean GS value) according to the spike characteristic with only a few exceptions. The accessions from the Qinghai-Tibet plateau formed a distinctive subgroup and can be distinguished from the concentrated group. The role of Tibet in the origin and evolution of cultivated barley has been discussed.  相似文献   

10.
黄颡鱼微卫星标记筛选及特征分析   总被引：3，自引：0，他引：3  
通过磁珠富集法首次筛选黄颡鱼微卫星标记并对其特征进行分析。用生物素标记的寡核苷酸探针(AC)8、(CT)8、(AT)7、(GATA)8、(GATT)7进行微卫星片断的富集,挑选部分阳性克隆测序获得38个含有微卫星的DNA序列,总计设计并合成了22对微卫星引物。以普通黄颡鱼基因组DNA为模板,进行PCR扩增,结果筛选出18个多态性微卫星标记,每对引物等位基因数2-8个（平均3.78）,遗传杂合度0.2225-0.8101（平均0.5755）,多态信息含量0.3425-0.7900（平均0.5336）。此外18对多态性微卫星引物中有16对在黄颡鱼属其它4种鱼类具有通用性,13对在鲇形目中的3种鱼类具有通用性。因此,可以推断筛选的多态性微卫星标记可用于黄颡鱼属和鲇形目鱼类的遗传分析。  相似文献   

11.
The management of genebank collections of cultivated potato is costly due to the need for in vitro maintenance and virus eradication. Therefore, it is important to set up conservation strategies, which prevent duplicates entering the collections. In this study, 32 Nordic potato landraces were studied for 57 morphological traits and analysed for amplified fragment length polymorphism (AFLP). Most landraces could be distinguished based on the morphological characters, except five accessions. Using five primer combinations to generate 114 reproducible AFLPs, of which 63 (55%) were polymorphic, the five morphologically indistinguishable accessions were placed into two groups with identical AFLP patterns, suggesting that some of the accessions were redundant for long-term preservation. The AFLP data showed that the Nordic collection of potato landraces is composed of genetically different clones, and morphological analysis revealed a wide range of variability. This variability seems to be distributed randomly over the Nordic region since the cluster analysis based on AFLPs and morphological traits revealed no grouping based on the country of origin. Principal component analysis suggests that fewer morphological traits than used in this study will be sufficient to discriminate between different genotypes of cultivated potato (Solanum tuberosum L.). Future possibilities for rationalising potato collections are discussed.  相似文献   

12.
Genetic diversity and relationships among 48 safflower accessions were evaluated using 22 inter-simple sequence repeats (ISSR) primers. A total of 429 bands were amplified, and 355 bands (about 82.7%) were polymorphic. Five to forty-one polymorphic bands could be amplified by each primer, with an average of 16.1 polymorphic bands per primer. The results showed that the polymorphism of the safflower germplasm was higher at the DNA level. All the 48 accessions could be distinguished by ISSR markers and were divided into 9 groups based on ISSR GS by using UPGMA method. The genetic relationships among the accessions from different continents were closer. Comparatively, the genetic diversity of the accessions originated from Asia was higher, from Europe assembled. The results also showed that the genetic variation of accessions from Indian and Middle Eastern safflower diversity centers were relatively higher. ISSR is an effective and promising marker system for detecting genetic diversity among safflower and give some useful information on its phylogenic relationships.  相似文献   

13.
Amplified fragment length polymorphism markers were evaluated to determine the genetic diversity and relationships among cultivated and weedy ryes (Secale cereale L.) using a large global set of accessions. On the basis of 395 polymorphic bands resulted from nine PstI-MseI primer combinations, cultivated rye exhibited higher average genetic diversity (Ht?=?0.34) than that of the weedy rye (Ht?=?0.27), however, it had lower genetic differentiation (Fst?=?0.16). The average genetic diversity of cultivated rye varied from region to region ranging from 0.21 to 0.31. As expected, all cultivated accessions clustered together both in dendrogram and principal coordinate diagram indicating common breeding program selection criteria based on similar value-added agronomic characteristics. A clustering of cultivated rye accessions into groups based strictly on geographical origin was not found. The relationships among cultivated, weedy and wild ryes were discussed.  相似文献   

14.
Glutenin largely determines wheat bread baking quality. As high-molecular-weight glutenin subunit (HMW-GS), related to Glu-1 loci, determines wheat flour elasticity, it correlates strongly with bread-making quality. This study was aimed at clarifying genetic variations in bread-making characteristics between East and West Asian wheat landrace germplasms, by investigating HMW-GS allelic composition of 1068 wheat accessions. Herein, the accession number having reported HMW-GS pattern in previous studies was 855. However, the accession number with newly detected HMW-GS patterns was 114. These new HMW-GS patterns were classified into 4 types based on similarity. Eight Korean accessions with these four types were identified. Concerning landrace germplasm nature, 99 accessions showed heterogeneous patterns caused by seed mixture. The Glu-1 loci allelic variation analysis, revealed that the percentages of Glu-A1c (73.6%), Glu-B1b (60.2%), and Glu-D1a (68.5%) were highest at Glu-A1, Glu-B1, and Glu-D1 loci, respectively. The incidence of preferable alleles for bread baking was high in Chinese accessions. In bread-making quality evaluation using Glu-1 score, 24 among 35 accessions with full score were from China. The polymorphic information content index of each origin based on HMW glutenin subunit combination showed that West Asian and neighboring-regional landraces, excluding Afghanistan ones, were more diverse than East Asian landraces excluding Chinese ones. Cluster analysis based on Glu-1 allelic combination showed that many Korean, Japanese, and Afghan accessions were in the same group. However, many Chinese and other West Asian accessions were in the other group despite geographical distance.  相似文献   

15.
The present study was performed to investigate genetic diversity of Kenyan landraces of the white-flowered gourd (Lagenaria siceraria), which exhibits tremendous morphological variation. RAPD analyses were performed on 53 landraces of the cultivated species L. siceraria and 42 accessions of three wild species (40 L. sphaerica, 1 L. abyssinica, and 1 L. breviflora). A total of 432 polymorphic bands were detected using 54 primers. The four species were clearly differentiated from one another. Intra-specific variations were investigated with L. siceraria and its wild relative L. sphaerica. Landraces of the cultivated species collected from different ethnic communities or regions were differentiated. Morphological variations were not associated with RAPD variations. Bitter landraces collected in Maasai communities showed two specific RAPD bands. In the wild species, accessions collected from the eastern and western sides of the Great Rift Valley were genetically differentiated from each other. In both species, genetic and geographical distance matrices computed among all pairs of accessions were significantly correlated, implying that the observed geographical variation can be explained by the 'Isolation by distance model'. Progeny plants derived from a common mother in L. siceraria showed a low level of segregation in RAPD pattern, suggesting that collected landraces are cultivated, maintaining their inherent traits although they are monoecious and insect-pollinated, whereas the wild relative L. sphaerica showed a higher level of segregation. The morphological diversity observed among landraces of L. siceraria is the result of human selection and their genetic identities are maintained by inbreeding probably resulting from frequent self-pollination.  相似文献   

16.
A total of 242 accessions of common wheat (Triticum aestivum L.) released in China since the 1940s were evaluated with AFLP (amplified fragment length polymorphism) technique. Genetic diversity was analyzed using five pairs of polymorphic primer combinations with 245 polymorphic bands. The highest genetic diversity was found in the accessions of the 1950s, and in the next place was that in the 1940s. The genetic diversity began to descend in the 1960s, and fell to the lowest in the 1970s. After that, the genetic diversity came back to some extent in the 1980s, however, it became much lower in the 1990s compared with that in the 1940–1950s. Landraces and introduced accessions from foreign countries showed greater genetic diversity in comparison to improved varieties. In addition, greater genetic diversity was observed in winter wheat. It was emphasized that great attention should be paid on further exploration of genetic diversity in wheat breeding program.  相似文献   

17.
Portuguese wheat landraces, ‘Arrancada’ were collected from the Aveiro region, Portugal before the 1950s. We found in eight accessions of `Arrancada' hexaploid wheat with the long glume phenotype. We assessed the comparative genetic diversity among Portuguese `Arrancada' wheat and Triticum petropavlovskyi Udacz. et Migusch. using AFLP assays and discuss the origin of long glumed `Arrancada' wheat. With the four primer pairs a total of 4885 visible bands were scored corresponding to 99 AFLP markers as putative loci, of which 55 markers (54%) were polymorphic. UPGMA clustering and PCO grouping showed that long glumed ‘Arrancada’ wheat and T. petropavlovskyi were genetically diverse. Long glumed ‘Arrancada’ hexaploid wheat separated into two clusters (groups) in both the UPGMA dendrogram and in PCO analysis. Four long glumed accessions fell in the cluster of tetraploid wheat. A similar argument could be made for another four accessions which belong to the cluster of hexaploid wheat. The substantial level of genetic variation indicated that long glumed ‘Arrancada’ wheat and T. petropavlovskyi originated independently. It is most likely that the P-gene of long glumed ‘Arrancada’ hexaploid wheat was introduced from T. turgidum ssp. polonicum (L.) Thell. to T. aestivum via natural introgression or breeding. We suggest that the long glumed ‘Arrancada’ hexaploid wheat did not originate from T. aestivum through spontaneous mutation at the P locus  相似文献   

18.
Guar [Cyamopsis tetragonoloba (L.) Taub.] is an important commercial crop of India, mainly cultivated in the northwestern part and neighboring areas of Pakistan. High morphological diversity is reported in guar. The present study attempts to analyze the genetic diversity in cultivated guar using allozyme polymorphism and compare it with reported morphological diversity. Accessions for the study were selected from a set of guar germplasm conserved at the National Bureau of Plant Genetic Resources, New Delhi. The morphological data of 108 selected accessions was subjected to UPGMA clustering. Fifty-five accessions were then picked randomly from the clusters generated. Tris-borate system (pH 8.3) was found to be most effective for detection of allozyme polymorphism in guar. Ten enzymes were selected for the study out of 18 systems tried, namely, malate dehydrogenase, malic enzyme, phosphogluco isomerase, glutamate oxaloacetate transaminase, esterase, peroxidase, alcohol dehydrogenase, glutamate dehydrogenase, glucose 6-phosphate dehydrogenase and shikimate dehydrogenase. A total of 20 loci were detected with 34 alleles. The number of polymorphic loci in different accessions was observed to be highly variable (0–9). An average of 1.27 allozyme per polymorphic locus was observed. The allele frequency data of the 55 accessions was used to determine genetic diversity parameters. The dendrogram generated on genetic distance showed three clusters in the distance range of 0–0.28. Most of the accessions were in the first clusters in a narrow distance range of 0–0.08. The second cluster consisted of improved varieties and accession from Pakistan. The third cluster of accessions was genetically more distant but there was no definite segregation of accessions according to the place of collection. The accessions from south west Rajasthan were scattered in all the three clusters showing higher variability in this region, also supported by higher morphological variation. The genetic distance was low among accessions of guar, indicating low diversity in India.  相似文献   

19.
大豆种质资源RAPD标记遗传多样性研究   总被引：1，自引：0，他引：1  
为深入研究并充分利用野生大豆资源,本文利用RAPD分子标记对40份大豆材料加以分析,旨在从DNA分子水平上探索野生大豆、地方品种和育成品种之间的遗传多样性状况。结果表明:50个RAPD引物筛选出具有多态性且扩增条带清晰的引物38个,共检测出407条带,其中多态谱带309条,多态性程度为75.92%。每个引物可扩增出2～14条多态性带,平均产生多态性谱带8.1条;平均多样性指数为2.3377,变幅范围为0.5865～4.2133。遗传相似系数变幅范围为0.44～0.92,平均为0.75。野生大豆的多态比例(94.35%)、多样性指数(2.2336)分别高于育成品种(87.47%、1.7331)和地方品种(83.54%、1.6198)。遗传相似系数为野生大豆(0.6498)地方品种(0.7015)育成品种(0.7177),育成品种与地方品种间为0.6599,育成品种与野生大豆间为0.6487,地方品种与野生大豆间为0.6045。UPGMA聚类分析结果表明,40份大豆材料聚为6类,育成品种和地方品种各自聚为一类,野生大豆聚为4类。野生大豆特异等位基因数远远高于育成品种和地方品种二者的相加之和。本研究从分子水平上揭示了野生大豆与栽培大豆区别明显,宜作为一个独立的种,同时野生大豆变异幅度大,遗传基础广,是大豆育种实践中的优良基因资源。  相似文献   

20.
为了探索中国大蒜种质个体的SSR位点的分布情况,为品种鉴定、保存及遗传改良提供分子生物学依据,利用6对SSR引物对40个大蒜(Allium sativumL.)品种进行聚类分析、主成分分析及遗传多样性评价。共检测到21个多态性位点,平均每对引物可扩增出约3.5条多态性片段,多态性百分率为56.76%;SSR引物组合平均有效等位基因数、Nei基因多样度和Shannon信息指数分别为1.5551、0.3414和0.5188。聚类分析显示,6对SSR引物可把40份大蒜种质资源从0.59相似系数水平上3个类群。第一类群包含28份种质,在相似系数为0.73的水平上进一步又被分成了3个亚类;第二亚类仅包含2份种质;第三亚类包含10份种质,在0.68的相似系数水平上分成了2个亚类。主成分分析和UPGMA的结果基本一致。不同地理来源的大蒜种质的Shannon-Weaver多样性指数的变幅为0.0576~0.4179,说明大蒜种质遗传多样性丰富。本研究利用SSR分子标记技术较准确地解析大蒜不同材料间的亲缘关系及遗传多样性,为中国大蒜SSR分子标记提供基础资料。  相似文献   

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