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1.
Andrographis paniculata is a medicinal plant of immense therapeutic value. The present study was aimed to elucidate its genetic diversity based on morphochemical and RAPD markers from 53 accessions belonging to 5 eco-geographic regions. Analysis of variance and D 2 statistics revealed significant differences in all the metric traits and sufficient inter-cluster distances indicating considerable diversity among the accessions. The complementary approach of RAPD was used to evaluate the genetic dissimilarities among all the accessions using 6 highly polymorphic primers. The average proportion of polymorphic loci across primers was 96.28%. The molecular genetic diversity based on Shannon index per primer averaged 5.585 with values ranging from 3.08 to 8.70 indicating towards wide genetic base. RAPD based UPGMA and D 2 cluster analysis also revealed that various accessions available in different eco-geographic regions might have originated from native places of wild abundance. Similarity matrices were generated for molecular markers and morphometric data to determine the degree of congruence between the two. A highly significant but low correlation (r = 0.547, P < 0.001) was obtained thus implying the correspondence between the two. The species is hermaphroditic and a habitual inbreeder. The present study yielded a typical triangular congruence between its breeding system, morphometric traits and RAPD markers thus elucidating the usefulness of complementary approaches to make diversity analysis more explanatory and purposeful for optimum genetic amelioration and effective conservation of its genotypic variability.  相似文献   

2.
Sweet potato (Ipomoea batatas L.) is the fifth most important crop in the developing countries after rice, wheat, maize and cassava. The amplified fragment length polymorphism (AFLP) method was used to study the genetic diversity and relationships of sweet potato accessions in the germplasm collection of Sokoine University of Agriculture, Morogoro and Sugarcane Research Institute, Kibaha, Tanzania. AFLP analysis of 97 sweet potato accessions using ten primer combinations gave a total of 202 clear polymorphic bands. Each one of the 97 sweet potato accessions could be distinguished based on these primer combinations. Estimates of genetic similarities were obtained by the Dice coefficient, and a final dendrogram was constructed with the un-weight pair-group method using arithmetic average. AFLP-based genetic similarity varied from 0.388 to 0.941, with a mean of 0.709. Cluster analysis using genetic similarity divided the accessions into two main groups suggesting that there are genetic relationships among the accessions. Principal Coordinate analysis confirmed the pattern of the cluster analysis. Analysis of molecular variance revealed greater variation within regions (96.19%) than among regions (3.81%). The results from the AFLP analysis revealed a relatively low genetic diversity among the germplasm accessions and the genetic distances between regions were low. A maximally diverse subset of 13 accessions capturing 97% of the molecular markers diversity was identified. We were able to detect duplicates accessions in the germplasm collection using the highly polymorphic markers obtained by AFLP, which were found to be an efficient tool to characterize the genetic diversity and relationships of sweet potato accessions in the germplasm collection in Tanzania.  相似文献   

3.
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4.
Total 65 lotus accessions in genus Nelumbo mainly collected from China, were subjected to random amplified polymorphic DNA (RAPD) markers to estimate the genetic diversity and to test the genetic basis of the relationships between morphotypes and molecular markers. Seventeen primers generated a total of 195 highly reproducible and discernible loci, among which 173 were polymorphic. Percent polymorphism varied from 66.7 to 100 with an average of 88.72, and five primers out of them, OPC05, OPG10, OPN20, OPP09 and OPS17, showed 100% polymorphism. A relatively high genetic diversity was detected among all the samples with the similarity coefficient values ranging from 0.45 to 0.85, and Nei’s gene diversity (h) 0.30, and Shannon index (I) 0.46. The UPGMA dendrogram clustered 65 accessions in four clusters and the clustering pattern showed two groups, N. nucifera ssp. nucifera and those accessions related to the American lotus, and some special cultivars, landraces, hybrids and the American lotus. Principal Coordinate Analysis (PCA) further indicated that the genetic diversity of Nelumbo accessions was not evenly distributed, instead, was presented by a clustered distribution pattern. Similar to the results revealed by the dendrogram, two main groups representing the two subspecies of N. nucifera, as well as some special landraces, cultivars of Chinese lotus, the Japanese lotus and hybrids out of the two groups were obtained. Neither the UPGMA dendrogram nor the PCA analysis exhibited strict relationship with geographic distribution and morphotypes among the accessions.  相似文献   

5.

Anchote (Coccinia abyssinica (Lam.) Cogn.) is a perennial root crop belonging to Cucurbitaceae family. It is endemic to Ethiopia and distributed over wide range of agro-ecologies. For further improvement and efficient conservation of this crop, characterization of its genetic diversity and its pattern of distribution is a vitally important step. Expressed sequence tags-simple sequence repeats (EST-SSRs) markers were developed from publicly available watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] ESTs in the GenBank database. Among those novel markers, eight were polymorphic and subsequently used for genetic diversity and population structure analyses of 30 anchote accessions collected from western Ethiopia. A total of 24 alleles were obtained across the eight polymorphic loci and 30 accessions that revealed moderate level of genetic diversity in this minor crop. Among the eight loci, locus CA_06 was the most informative with six alleles and polymorphic information content (PIC) of 0.76. The accessions showed about threefold variation in terms of genetic diversity, with expected heterozygosity (He) ranging from 0.15 (accession An) to 0.44 (accession Dg). Other accessions with higher genetic diversity include Ar and Gu (He?=?0.43 and 0.41, respectively). Analysis of molecular variance (AMOVA) revealed that the variation within accessions and among accessions accounted for 84.7% and 15.3% of the total variation, respectively. The study revealed low but significant population differentiation in this crop with no clear pattern of population structure. The EST-SSR markers developed in this study are the first of their kind for anchote and can be used for characterization of its wider genetic resources for conservation and breeding purposes.

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6.
The extent and patterns of distribution of genetic variation among 80 sorghum (Sorghum bicolor (L.) Moench) germplasm accessions from Ethiopia and Eritrea were investigated using RAPD with 20 oligonucleotide primers. The primers generated a total of 147 polymorphic bands across the 80 accessions with a mean of 7.35 bands per primer. Estimation of the extent of variation by the Shannon-Weaver diversity index revealed an intermediate level of overall variation (H = 53), although the levels varied among regions of origin of the accessions. Partitioning of the total variation revealed considerable variation (77%) within the region of origin of the accessions and the remainder (23%) among regions of origin. Similarly, a large portion (94%) of the total variation was found within the adaptation zones compared to among the adaptation zones (6%). The results suggest a weak differentiation of the sorghum material both on regional and agro-ecological bases, which could be ascribed to the high rate of outcrossing in cultivated sorghum and its free natural hybridization with its wild and weedy relatives, as well as to seed movement by humans. The average genetic dissimilarity was found to be 36% among the 80 accessions and 13% among the 15 regions of origin. Cluster analysis failed to group accessions of the same region or the same adaptation zone, which further confirmed the weak differentiation of the material studied. The clustering pattern of the regions of origin was broadly concordant with previous clustering patterns obtained using morphological characters, in which regions with broad agro-climatic conditions were grouped together.  相似文献   

7.
Oryza granulata, an upland wild rice species, represents an unique germplasm for possessing abilities of tolerance to shade and drought, immune to bacterial blight and resistance to brown planthopper. Although low degree of genetic variability has been revealed within its populations, little genetic information at the species level is available in determining rational conservation strategies. Here we used dominant DNA marker random amplified polymorphism DNA (RAPD) to assess the genetic variability among 23 accessions of O. granulata that collected from main distribution areas worldwide. Twenty decamer primers generated a total of 243 bands, with 83.5% of them (203 bands) being polymorphic. Calculation of Shannon index of diversity revealed an average value of 0.42 ± 0.25, indicating that O. granulata maintains a relatively high degree of genetic diversity on the species level. Analysis of genetic dissimilarity (GD) showed that genetic differentiation occurred among studied accessions, which supports the feasibility of current ex situ conservation strategies. We also suggested that information based on population studies, which could be achieved by international co-operation, is needed to conserve this widespread germplasm more effectively.  相似文献   

8.
Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the semi-arid regions of the world including Asia and Africa. Its genetic diversity is contained mostly in traditional varieties and modern cultivars used by farmers. In this study, agro-morphological traits and molecular markers were used to assess genetic diversity in 22 accessions of cultivated sorghum from five countries (Botswana, Namibia, Swaziland, Zambia and Zimbabwe) in the Southern African Development Community (SADC) region. The study revealed a significant variation among 22 accessions in both qualitative and quantitative morphological traits, indicating the accessions’ promising potential as breeding material. For molecular analysis, 11 microsatellite primer-pairs were used, and generated a total of 70 alleles across 20 accessions. Analysis of molecular variance revealed a high level of genetic variation; 67 % among the accessions and 10 % among the five countries. The patterns of genetic diversity and the relationships observed in this study should provide insights for genetic resource conservation and utilization of sorghum germplasm in the SADC region.  相似文献   

9.
As an oilseed crop, the cultivation of Ethiopian mustard (Brassica carinata) is restricted only to Ethiopia. Even though geographic diversity is a potent source of allelic diversity, the extent of genetic diversity among germplasm material of Ethiopian mustard from different countries has not been assessed. Forty-three accessions, comprising 29 accessions from eight different geographic regions of Ethiopia and 14 exotic accessions from Australia, Pakistan, Spain, and Zambia were analysed for their genetic diversity using random amplified polymorphic DNA (RAPD) technique. A set of 50 primers yielded a total of 275 polymorphic bands allowing an unequivocal separation of every Ethiopian mustard accession. The usefulness of the 50 RAPD primers in measuring heterozygousity and distinguishing accessions was variable such that polymorphic information content (PIC) varied from 0.05 to 0.40, band informativeness (BI) from 0.05 to 0.65 and primer resolving power (RP) from 0.15 to 6.83. Jaccard's similarity coefficients ranged from 0.44 to 0.87 indicating the presence of a high level of genetic diversity. On the average, Australian and Ethiopian accessions were the most similar while, Spanish and Zambian accessions were the most distant ones. Cluster analysis grouped the 43 accessions into four groups, which has quite a high fit (r = 0.80) to the original similarity matrix. With no prior molecular information, the RAPD technique detected large genetic diversity among the 43 accessions from five different countries and their grouping by dendrogram and principal coordinate analysis (PCoA) was inclined towards geographic differentiation of RAPD markers. Conversely, RAPD differentiation along geographic origin was not apparent within the Ethiopian accessions.  相似文献   

10.
AFLP markers were used to characterize diversity and asses the genetic structure among 17 accessions of kale landraces, cultivars and wild populations from Europe. The range of average gene diversity in accessions was 0.11–0.27. Several landraces showed higher levels of diversity than the wild populations and one cultivar had the lowest diversity measures. The landraces that were most genetically diverse were from areas where kales are known to be extensively grown, suggesting in situ conservation in these areas as a supplement to storage of seeds in gene banks. An analysis of molecular variance (AMOVA) showed that 62% of the total variation was found within accessions. For most accessions, genetic distance was not related to geographic distance. Similarities among accessions were probably not caused by recent gene flow since they were widely separated geographically; more likely the relationship among them is due to seed dispersal through human interactions. Our results indicate that a kale population found in a natural habitat in Denmark was probably not truly wild but most likely an escape from a cultivated Danish kale that had subsequently become naturalized.  相似文献   

11.
Using the 8 specific primer pairs based on the conserved motifs of plant resistance genes, the plant disease resistance gene analog polymorphisms (RGAPs) in 15 wild emmer wheat (Triticum dicoccoides) populations from Israel had been detected. High genetic variations at the RGAP loci were observed in T. dicoccoides populations. A total of 254 discernible bands were obtained among 115 accessions, and 192 bands (75.6%) were polymorphic. Each genotype had a unique banding profile, and the genetic similarity coefficient ranged from 0.094 to 0.862. In T. dicoccoides, the proportion of polymorphic loci (P), the genetic diversity (He) and Shannon’s information index were 0.756, 0.362 and 0.541, respectively. The proportion of polymorphic loci (P) per population averaged 0.732 (range: 0.515–0.932); genetic diversity (He) averaged 0.271 (range: 0.212–0.338); and Shannon’s information index averaged 0.404 (range: 0.310–0.493). The coefficients of genetic distance (D) among populations averaged 0.107 (range: 0.043–0.178), and the results of Mantel test (r = 0.168, P = 0.091) showed that the estimates of genetic distance were geographically independent. Neighbor-joining cluster analysis suggested that the genetic relationships of T. dicoccoides populations were associated with their ecogeographic distribution. The hierarchical analysis of molecular variance (AMOVA) and the coefficient of gene differentiation (G ST ) values revealed that most of the variations were presented within populations, although significant differences among populations and regions were also detected. The values of P and Shannon’s information index were negatively correlated with the two factors: Tdd (day–night temperature difference) and Ev (mean annual evaporation), whereas they were positively correlated with one water factor: Rn (mean annual rainfall). The correlation matrix between He in the RGAPs and geographic variables contained 20 significant (P < 0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at RGAP loci at least partly correlated with ecological factors.  相似文献   

12.
A collection of sorghum, including more than 12,000 Chinese landraces, has been constructed and maintained in China. However, the genetic diversity of Chinese sorghum landraces has not been fully investigated, and the origin of Chinese sorghum is still in dispute. In this study, the complete chloroplast genome sequence of sorghum line Tx623B was searched for simple sequence repeats (SSRs). 31 SSR loci with at least 10 mononucleotide repeats or five dinucleotide repeats were identified, and primer pairs for 27 loci were designed. Chloroplast DNA variation in cultivated sorghum was investigated by using these primer pairs on 185 Chinese sorghum landraces and 70 cultivated sorghum accessions from other countries. Among the 27 loci, 14 were polymorphic. The number of alleles per polymorphic locus ranged from 2 to 5 with an average of 2.79. Allelic data at 14 polymorphic loci were combined to give 12 haplotypes. The average allelic diversity index across the 14 polymorphic loci and corresponding haplotype diversity were markedly lower for Chinese sorghum landraces than were those for accessions from other countries. However, Chinese sorghum landraces shared a predominant allele at each polymorphic locus and a predominant haplotype with foreign accessions. Our results indicate that Chinese landraces experienced a severe maternal bottleneck during the introduction process with a predominant haplotype being present in 171 of 185 accessions analyzed. Except for one rare exception, haplotypes found in Chinese landraces were either identical or closely related to those found in foreign accessions and could not be separated clearly from them by cluster analysis. Our results are consistent with the hypothesis of African origin of Chinese sorghum.  相似文献   

13.
Genetic diversity among 26 cucumber (Cucumis sativus L. var. sativus) accessions from five African countries [Algeria (1), Egypt (21), Ethiopia (2), Kenya (1), and Libya (1)] present in the U.S. National Plant Germplasm System (NPGS) were examined by assessing variation at 71 polymorphic random amplified polymorphic DNA (RAPD) loci. Genetic distances (GD; simple matching coefficient) were estimated among these African accessions and a reference array (RA) of 21 accessions representative of the genetic variation in cucumber. GD among African accessions ranged between 0.41 and 0.97. GD among accessions in the reference array ranged between 0.36 and 0.88. Multivariate analysis identified three distinct groupings (1–3) of African accessions; Group 1 contained 21 accessions (Egypt, Ethiopia and Libya), Group 2 consisted of two accessions (Kenya, Algeria), and Group 3 possessed three accessions (Egypt). These groupings were distinct from each other (P > 0.001). Accessions in Group 1 differed genetically from all other accessions examined (P > 0.01), and accessions in Groups 2 and 3 were uniquely associated with several RA accessions. While GD among accessions in Group 1 ranged between 0.52 and 0.90, distances among Group 2 accessions varied between 0.93 and 0.97. The GD between the two accessions in Group 3 was 0.65. An accession from Syria (PI 181874) and from one Turkey (PI 199383) were genetically more similar to accessions in Group 1 than to other accessions in the RA. Likewise, accessions in Group 2 were genetically similar to two RA accessions from China and a European glasshouse cucumber line, and Group 3 accessions showed genetic affinities with the U.S. market class cultivar Dasher II. Data suggest that some Egyptian accessions (Group 1) possess unique genetic variation, that this germplasm has potential for broadening the genetic base of commerical cucumber, and that further collection of African germplasm is likely to enhance genetic diversity of cucumber in NPGS.  相似文献   

14.
The molecular diversity and population structure present in the Ethiopian sorghum collection maintained at the USDA–ARS National Plant Germplasm System (NPGS) has not been studied. In addition, 83 % of the accessions in the Ethiopian collection lack passport information which has constrained their evaluation and utility. Therefore, 137 Ethiopian accessions from NPGS were randomly selected and characterized with 20 strategically selected simple sequence repeat markers. These markers indentified 289 alleles with average polymorphic information content of 0.78. The allele frequency distribution reflects that 62 % of the alleles were rare (<0.05), 17 % range from 0.05 to 0.10, and 22 % were higher than 0.10. Expected and observed heterozygosity were estimated at 0.78 and 0.23, respectively, demonstrating Ethiopia has high sorghum genetic diversity germplasm. Population structure analysis indentified two subpopulations of 77 and 41 accessions, respectively, while a third group was constituted by 19 accessions whose classifications were not defined (i.e. hybrids). Analysis of molecular variances determined variation within subpopulations as the major source of variation. Likewise, genetic differentiation between subpopulations was moderate (Fst = 0.10). These results indicated that a continuous exchange of genes between subpopulations of sorghum exists in Ethiopia. The absence of a well defined population structure positioned this germplasm as an important resource for the study and dissection of agricultural traits by association mapping. However, genetic redundancy analysis indicated the presence of highly related accessions, therefore, strategic selected accessions must be consider prior to phenotype evaluation of larger number of accessions. The Ethiopian collection is composed of highly genetically diverse germplasm, and the genetic information presented herein is valuable to ex situ and in situ conservation programs to promote the use of this germplasm for breeding programs.  相似文献   

15.
Germplasm conserved as seeds in genebanks requires regular regeneration. In this process, selection and genetic drift may cause loss of genetic diversity from accessions. In the case of selfing crops, separation of distinct lines into different accessions may be an efficient strategy to avoid these negative effects. In order to evaluate the applicability of this method for collection management, knowledge about the level of intra-accession genetic diversity is required. By means of AFLP analysis intra-accession variation was investigated in two cultivars, two landraces and two wild populations of ex situ conserved barley germplasm. In the total sample of 216 individuals analysed (36 per accession), 22 genotypes were observed based on 104 polymorphic loci. The number of genotypes detected ranged from 1 to 3 per accession, except for a Nepalese landrace that revealed 12 genotypes. An UPGMA cluster analysis grouped the genotypes unambiguously into the accession they belonged to and genotypes within accessions were generally found to be closely related. In order to determine the repeatability of the results obtained, 11 individuals belonging to 4 genotypes from the Nepalese landrace were scored for a second set of AFLP markers. Matrices of genetic distances calculated for the two AFLP datasets were found to be highly correlated (r = 0.9346, P < 0.001). Separation of genotypes into different accessions was considered a relevant option only for the Nepalese landrace. Analysis of molecular variance indicated that this accession could be well divided into 8 distinct lines. Further implications of the results for genebank practices are discussed.  相似文献   

16.
We established protocols for the analysis of genetic diversity in chayote (Sechium edule) by using isozyme markers, thereby determining the level of genetic diversity present in 42 accessions of chayote from Costa Rica. We obtained clear and reproducible zymograms for eight enzyme staining systems: PGM, 6-PGD, PGI, IDH, MDH, SOD, SKD, and EST, and were able to score 14 putative loci. Eight of the 14 loci examined were polymorphic. We found 35 distinct multilocus genotypes among these accessions. Five of these multilocus genotypes were homozygous for all loci. In addition, our data also revealed that most of the multilocus genotypes (24) were heterozygous for only one of the eight loci, and the rest were heterozygous for two or three loci (9 and 4 accessions, respectively). Seven multilocus genotypes were found in two different accessions. Dice similarity coefficient was used to study the relationship between accessions. This analysis, based on the presence and absence of alleles, revealed that accessions collected in the same location seldom shared the same multilocus genotype. The value of isozyme polymorphisms as tools to continue studies on the characterization of chayote is discussed.  相似文献   

17.
The genetic diversity of 38 cultivated populations of Sesamum indicum L. from four different regions of Turkey was estimated at the DNA level with the random amplified polymorphic DNA (RAPD) technique. Sixty-one bands were obtained for all populations 78% of which were polymorphic. Analysis of molecular variance (AMOVA) was used to investigate the genetic diversity of the populations which yielded highly significant differences among populations within regions (91.9% of the total genetic diversity). According to AMOVA and Shannon's index that were performed separately for each region, the highest value of genetic variation was observed among Northwest region populations (CV = 7.7; H0 = 0.304) and lowest in the Southeast regions' populations (CV = 2.6; H0 = 0.068). Nei and Li's similarity index was calculated and phylogenetic tree was established using the neighbor-joining algorithm. This phenetic analysis grouped 35 of 38 accessions in six groups leaving three highly diverse accessions outside. Wagner phylogenetic method was used to assess the phylogenetic relationships among the populations. In the majority-rule consensus tree, only 7 of the 32 forks showed above 60% occurrence. Using Principal Coordinate Analysis (PCO) of the RAPD data set, the groups were clearly separated along the first three axis. These results indicate that RAPD technique is useful for sesame systematics, and should be valuable for the maintenance of germplasm banks and the efficient choice of parents in breeding programs.  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.
Summary Management of a genetic resources collection is more effective if a curator can accurately identify genotypes and accessions as well as assess intraspecific genetic relationships and the genetic structure of species. Consequently, a study was conducted to determine whether data from starch gel electrophoresis of a specific set of isozymes from plants of Brassica oleracea (cole crops) would be useful in answering four questions the answers to which are essential for effective curatorial activities: Can individual plants be identified? Can specific accessions be identified? What are the genetic relationships among botanical varieties within B. oleracea? What is the genetic structure of the species B. oleracea? Six loci from 4 enzyme systems (LAP, PGD, PGI, and PGM) were analyzed. Individuals and accessions could not usefully be identified using these isozymes, but genetic relationships within and genetic structure of the species were easily determined, resulting in specific recommendations for improving collection management. As expected, highly selected commercial lines exhibited less diversity than average, and so may be of limited value when trying to maximize diversity with a minimum number of accessions. In contrast, landraces and weakly selected lines are more diverse than average, and thus are useful in maximizing per accession diversity. Not only was 93% of the genetic variability in B. oleracea found among accessions and a mere 7% among varieties, but also a cluster analysis showed that accessions of a single botanical variety are often more similar to those of a different variety than to each other. These results suggest that in order to create a genetic resources collection of B. oleracea that faithfully represents the diversity in the species, a curator should assemble a broad array of accessions originating from diverse agroecological niches, having different levels of improvement, and representing all botanical varieties.Abbreviations LAP Leucine amino peptidase - PGD 6-Phosphogluconate dehydrogenase - PGI Phosphoglucoisomerase - PGM Phosphoglucomutase - RAPD Random amplified polymorphic DNA - RFLP Restriction fragment length polymorphism - UPGMA Unweighted pair-group method using arithmetic averages  相似文献   

20.
Rice genetic diversity partitioning between farms, varieties and, within-variety diversity, were analysed in two villages of Maritime Guinea with contrasted agroecological conditions. One thousand and two hundred individual plants belonging to 45 accessions collected in eight farms were genotyped using 10 SSR markers. The molecular variance was evenly shared between and within accessions, while the farm effect was almost nil. Local varieties had a multi-line genetic structure. The number of multilocus genotypes was proportional to the utilisation rate of the variety in the village. The F ST values between different accessions of each variety were significant which indicated low genetic consistency in the variety names. This varietal structure could mainly be explained by the migration phenomenon and the high varietal turnover. Compared to allelic diversity, multilocus genotypic diversity seemed to be the most suitable indicator of the quantitative distribution of diversity at different management scales (accession, farm and village). The within- and between-farm F ST values were in the same order of magnitude. The within-farm diversity was not farm-specific but quantitatively high, i.e. up to 50% of the total genotypic diversity of a given village. Given the relative importance of the within-variety diversity, the in situ approach stands out as the most effective solution. As farms do not host specific diversity the in situ approach could be implemented by working with a small number of farms.  相似文献   

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