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1.
Results of archaeological studies indicate a millennia-old cultivation history for wheat (Triticum spp.) in Oman. However, in spite of numerous collection surveys and efforts for phenotypic characterization of Omani wheat landraces, no attempts have been made using molecular tools to characterize this germplasm. To fill this gap, 29 microsatellite markers revealing 30 loci were used to study the genetic diversity of 38 tetraploid wheat landrace accessions comprising the species T. dicoccon, T. durum and T. aethiopicum. A total of 219 alleles were detected whereby the number of alleles per locus ranged from 2 to 16 with an average number of 7.1 alleles per locus. The highest number of alleles occurred in the B genome with on average 7.9 alleles per locus as compared to the A genome with 6.5 alleles per locus. Heterogeneity was detected for all microsatellites except for GWM 312, GWM 601 and GWM 192B with an average heterogeneity over all primers and lines of 14.4%. Approximately 10% of the accessions contained rare alleles with an average allele frequency <4%. Gene diversity across microsatellite loci ranged from 0.26 to 0.85. The pairwise comparison of genetic similarity ranged from 0.03 to 0.91 with an average of 0.2. Cluster analysis revealed a clear separation of the two species groups T. dicoccon versus T. durum and T. aethiopicum. Within the species clusters regional patterns of subclustering were observed. Overall, this study confirmed the existence of a surprisingly high amount of genetic diversity in Omani wheat landraces as already concluded from previous morphological analyses and showed that SSR markers can be used for landraces’ analysis and a more detailed diversity evaluation.  相似文献   

2.
Accurate and reliable means for identification are necessary to assess the discrimination between landraces of tetraploid wheat [T.␣turgidum L. subsp. durum (Desf.) Husn.] and hexaploid wheat (T. aestivum L. em. Thell.). In Afghanistan, farmers usually cultivate mixed landraces, and thus distinction between bread and durum is difficult. A set of 18 microsatellites derived from the DuPont EST-database were used to describe genetic diversity in a sample of 82 Afghan wheat landraces. A total of 101 alleles were detected, with allele number per locus ranging from 2 to 13, and a mean allele number of 6.31. The percentage of polymorphic loci was 89%. The EST-SSRs markers showed different level of gene diversity: the highest Polymorphism Information Content value (0.921) was observed with DuPw 221. Our results demonstrated that with a reasonable number of expressed sequences target microsatellites (EST-SSRs) it is possible to discriminate between T. durum and T. aestivum species of wheat germplasm. Our results showed that EST-databases could be a useful source for species-specific markers and have the potential for new genic microsatellites markers that could enhance screening germplasm in gene banks.  相似文献   

3.
A comprehensive characterization of crop germplasm is critical to the optimal improvement of the quality and productivity of crops. Genetic relationships and variability were evaluated among 63 durum wheat landraces from the Mediterranean basin using amplified fragment length polymorphisms (AFLPs) and microsatellites markers. The genetic diversity indices found were comparable to those of other crop species, with average polymorphism information content (PIC) values of 0.24 and 0.70 for AFLP and microsatellites, respectively. The mean number of alleles observed for the microsatellites loci was 9.15. Non-metric multi-dimensional scaling clustered the accessions according to their geographical origin with the landraces from the South shore of the Mediterranean Sea closely related. The results support two dispersal patterns of durum wheat in the Mediterranean basin, one through its north side and a second one through its south side.  相似文献   

4.
The present study demonstrates utilization of 11 microsatellite markers to explore genetic diversity held in Perilla frutescens (L.) Britt. landrace accessions growing on farms in different parts of Korea and Japan and to assess their genetic relationships. All microsatellite loci were polymorphic and produced a total of 96 alleles ranging from 4 to 20, with an average of 8.7 alleles per locus. Of the 96 alleles found, a total of 15 unique landrace-specific alleles were observed at 9 different loci. The locus GBPFM203 provided the highest number of alleles (20), of which five were unique and each specific to a particular landrace accession. The occurrence of unique, accession-specific alleles presented molecular evidence for the generation of new alleles within on-farm collection of Perilla. The mean values of observed (H O) and expected heterozygosity (H E) were 0.39 and 0.68, respectively, indicating a considerable amount of polymorphism within this collection. A genetic distance-based phylogeny grouped the two Perilla varieties, var. frutescens and var. crispa (Thunb.) Decne into two distinct groups. Accessions belonging to var. frutescens could also be divided into two subgroups at a close genetic distance (GD = 0.432). The overall clustering pattern did not strictly follow the grouping of accessions according to their geographic origins. These observations are indicative of extensive germplasm exchange among farms from different geographical regions. The genetic similarity observed among the Perilla landraces may be useful for future Perilla crop variety identification, conservation, and improvement programs.  相似文献   

5.
Little is known about genetic diversity and geographic origin of wheat landraces from Oman, an ancient area of wheat cultivation. The objectives of this study were to investigate the genetic relationships and levels of diversity of six wheat landraces collected in Oman with a set of 30 evenly distributed SSR markers. The total gene diversity, (HT), conserved in the three durum wheat (Triticum durum desf.) landraces (HT = 0.46) was higher than in the three bread wheat (Triticum aestivum L.) landraces (HT = 0.37), which were similar to Turkish and Mexican bread wheat landraces calculated in previous studies. Genetic variation partitioning (GST) showed that variation was mainly distributed within rather than among the durum (GST = 0.30) and bread wheat (GST = 0.19) landraces. Based on modified Rogers’ distance (MRD), the durum and bread wheat landraces were distinct from each other except for a few individuals according to principal coordinate analysis (PCoA). One bread wheat landrace (Greda) was separated into two distinct sub-populations. A joint cluster analysis with other landraces of worldwide origin revealed that Omani bread wheat landraces were different from other landraces. However, two landraces from Pakistan were grouped somewhat closer to Omani landraces indicating a possible, previously unknown relationship. Implications of these results for future wheat landrace collection, evaluation and conservation are discussed.  相似文献   

6.
The genetic diversity in a Triticum durum Desf. collection, consisting of 102 Bulgarian landraces, nine Bulgarian and 25 introduced cultivars was studied using 14 highly polymorphic microsatellite markers. A total of 100 alleles were identified, with an average of 7.14 alleles per marker. The gene diversity values (He) of the markers for the total samples ranged from 0.23 (WMS357 and WMS631) to 0.77 (WMS46), with an average of 0.52. Within the landraces that were collected from 18 sites in Southern Bulgaria showed 2–11 alleles per locus with an average of 6.07. The microsatellite analysis suggests that the genetic diversity among landraces is lower compared to the diversity levels for durum wheat in countries close to the main centers of wheat domestication. Breeding activities have caused significant reduction of the allelic polymorphism, elimination of rare alleles, and increase in the number of common alleles and the frequency of dominating alleles.  相似文献   

7.
Bread wheat (Triticum aestivum L.) landraces held within ex situ collections offer a valuable and largely unexplored genetic resource for wheat improvement programs. To maximise full utilisation of such collections the evaluation of landrace accessions for traits of interest is required. In this study, 250 accessions from 21 countries were screened sequentially for tolerance to aluminium (Al) using haematoxylin staining of root tips and by root regrowth measurement. The staining test indicated tolerance in 35 accessions, with an intermediate response to Al exhibited in a further 21 accessions. Of the 35 accessions classified as tolerant, 33 also exhibited increased root length following exposure to Al. The tolerant genotypes originated from Bulgaria, Croatia, India, Italy, Nepal, Spain, Tunisia, and Turkey. AFLP analysis of the 35 tolerant accessions indicated that these represent diverse genetic backgrounds. These accessions form a valuable set of germplasm for the study of Al tolerance and may be of benefit to breeding programs for expanding the diversity of the gene pool from which tolerant cultivars are developed.  相似文献   

8.
Field and controlled environmental tests indicated that the 49 accessions of closely related species and 12 landraces of wheat (Triticum aestivum L. em. Thell.) from the National Gene Bank of China showed different reactions to powdery mildew (Blumeria graminis (DC.) E. O. Speer. f. sp. tritici) and stripe rust (Puccinia striiformis Westend f. sp. tritici) at adult and seedling stages. Unknown Pm genes or alleles were postulated with Triticum baeoticum Boiss. accessions BO 3 and Triticum monococcum L. MO 4 and MO 5 when inoculated with 21 powdery mildew isolates at seedling stage. Fourteen accessions of T. baeoticum, T. monococcum, Triticum durum, and wheat landraces were inoculated with 30 stripe rust isolates at seedling stage. Unknown Yr genes or alleles were postulated with T. baeoticum Boiss. accession BO 5, as well as wheat landraces Xiaobaimai, Laomangmai, and Shaanxibai. Heterogeniety in reaction to powdery mildew isolates and stripe rust races were observed in related species and landraces of wheat.  相似文献   

9.
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   

10.
Morphological spike diversity of Omani wheat   总被引：2，自引：2，他引：0  
Little is known about the diversity of field crops in Oman. The objective of this study therefore was to characterize wheat accessions from this country using individual spikes collected from different wheat cultivation areas. The phenotypic assessment of 15 qualitative and 17 quantitative characters showed variations among Omani wheat landraces. The standardized phenotypic diversity index (H′) was with 0.66 higher for quantitative characters than for qualitative characters (0.52) in tetraploid wheats and with 0.63 and 0.62, respectively, in hexaploid wheats. Overall, the morphological data revealed a surprisingly high diversity among landraces and showed that simple morphological characters can be used for an effective characterization of diversity in Omani wheat.  相似文献   

11.
Little is known about the diversity of wheat (Triticum spp.) in Oman. Results of a survey conducted in two remote mountain oases of northern Oman indicate that there exists considerable morphological variation within and among the five traditional landraces of wheat cultivated. Within two of the landraces grown on irrigated terraces, sized between 2 and 100 m2, two new botanical wheat varieties (Triticum aestivum var. baladseetense and var. maqtaense) were identified of which the agronomic properties, in particular tolerance to drought and heat, and the nutritional value require further investigation.  相似文献   

12.
We used amplified-fragment-length polymorphism (AFLP) markers to evaluate genetic variation in a set of bread wheat (Triticum aestivum L.) landraces and improved materials. Landraces collected from different geographic and agro-ecological zones in Pakistan in 1987, 1989 and 1991 were separated into two groups based on their geographic origins: northern (Himalaya) and south-western (Balochistan) Pakistan. Six AFLP primer combinations detected 453 AFLP markers in the 43 landrace accessions and four high-yield varieties (HYVs). Of these, 225 (49.67%) were rare (shared with < 5% of all accessions). Among these rare alleles, 23 (10.22%) were common in the Himalaya (shared with > 10% of accessions collected there) but were not found in Balochistan. We conclude that there is a higher probability of collecting rare alleles at overall, but which are in contrast locally common ones in the Himalayan region. Gene diversity was 0.17 in the Himalayan group and 0.15 in the Balochistan group. Considerable genetic variability was found in both groups. Accessions from different agro-ecological zones were indistinguishable by cluster analysis, indicating intensive seed trading within the country. Cluster analysis indicated that the landraces and the HYVs are genetically distinct; suggesting that genetic erosion of wheat landraces has been unlikely taken in place. This study provides an example of how analysis of existing materials and data, can serve as a basis for future collection planning and conservation policies.  相似文献   

13.
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   

14.
The polymorphism of gliadins was studied in 98 Bulgarian durum wheat (Triticum durum Desf.) landraces and classified according to the existing catalogues of blocks of gliadin components. In total, 31 alleles, including 12 new ones, were revealed for five gliadin-coding loci. Nine allele families, which included several alleles coding similar blocks differed only by minor components, were found. The gliadin loci had a high genetic diversity (H = 0.70), and Gli-A2 d was the most polymorphic locus. Significant differences in allele distribution were observed through the Bulgarian region under study. The results made it possible to explain the distribution by historical factors. Presumably, the genetic material flew into the country via two different ways and different durum wheat subgroups contributed to the formation of Bulgarian landraces. The landraces were a result of long-term selection and, probably, had a close association with the history of the human populations of the region.  相似文献   

15.
Temporal variation of diversity in Italian durum wheat germplasm   总被引：1，自引：0，他引：1  
The aim of this work is to analyse the temporal change of genetic diversity in Italian durum wheat germplasm. The germplasm deployed in this study (158 accessions), belonging to 5 different historical classes, was characterised for its microsatellite and gliadin markers. The level of genetic diversity (He), based on gliadin and SSR markers results – on average – greater in indigenous landraces present in Italy before 1915, with the exception of pure line material which had been selected from landraces (showing highest level of heterozigosity for gliadin markers). Genotypes obtained from crosses or mutagenesis (referring to the 1950–1960 period) along with those resulting from crosses between CIMMYT lines and old materials (1970s and beyond) were also genetically more diverse. Forty-nine percent of indigenous landraces were genetically heterogeneous. Nine out of 53 landrace accessions were able to capture 4 different SSR private alleles. It is speculated that the reduction of allele richness is an indicator of the genetic erosion of the pre-breeding germplasm and it is pointed out that the implementation of appropriate methods of genetic conservation of this germplasm is a priority for breeding and food safety.  相似文献   

16.
Random amplified polymorphic DNA markers (RAPD) were used to estimate the variability of 35 tomato accessions (Lycopersicon esculentum Mill.). A total of 257 reproducibly scorable bands were obtained from 20 primers, 78.6% of which were polymorphic. The percentage distribution of RAPD markers shows a bimodal distribution, and the frequency of rare alleles is similar in commercial and landrace accessions. Genetic distances among accessions were calculated and a dendrogram showing the genetic relationships among them was constructed allowing for the separation of four groups. Twenty out of 23 Brazilian landraces fell within one group, whereas commercial cultivars were distributed in the four groups. AMOVA analysis of RAPD data showed that, despite the high within Brazilian landraces and commercial cultivars variation, these two groups are significantly different, indicating that landraces can be a source of variation for breeding programs.  相似文献   

17.
The extent and patterns of microsatellite diversity in 141 Ethiopian tetraploid wheat landraces consisting of three species Triticum durum Desf., T. dicoccon Schrank and T. turgidum L. were analyzed using 29 microsatellite markers. A high level of polymorphism and a large number of alleles unique for each species were detected. Compared to emmer (T. dicoccon) and poulard (T. turgidum) wheats, a higher genetic diversity was observed in T. durum. The A-genome was more polymorphic than the B-genome in all the three species. Microsatellites with (GA) n -repeats had a higher number of alleles than (GT) n -repeats. A species pairwise comparison was made to determine the percentage of shared alleles and a large number of common alleles among species were observed. Average gene diversity, across the 29 microsatellite loci, was 0.684 for T. durum, 0.616 for T. dicoccon and 0.688 for T. turgidum. Genetic distances were lower between T. durum and T. turgidum (0.26) than between T. durum and T. dicoccon (0.34) or between T. turgidum and T. dicoccon (0.38). A significant correlation (p < 0.01) was found between the number of alleles per locus and the gene diversity in all the three species. Allelic frequency variation was highest between T. turgidum and T. dicoccon (10.62%) and lowest between T. durum and T. turgidum (4.86%). A genetic similarity coefficient of 0.34, 0.46 and 0.37 was found in T. durum, T. dicoccon, and T. turgidum, respectively. The dendogram, which was constructed on the basis of a similarity matrix using the UPGMA algorithm, distinguished all accessions represented in the study.  相似文献   

18.
Genetic diversity and population genetic structure of Aegilops tauschii in Northern Iran were studied based on nine microsatellite loci. A high level of genetic diversity was observed from the accessions collected from six regions (provinces). These accessions include 79 samples of the two subspecies (tauschii and strangulata), the intermediate form (among morphologically distinguished subspecies) and ten accessions of Triticum aestivum. The nine microsatellites revealed a total of 141 alleles, with an average of 15.7 alleles per locus. A comparison of the parameters showing genetic diversity, including the observed heterozygosity (Ho), gene diversity (He) and Shannon’s information index (I) of Ae. tauschii accessions from different provinces in Northern Iran, indicated that subsp. tauschii possesses the highest genetic diversity, followed by intermediate form. Genetic distance between subsp. strangulata and subsp. tauschii was low, confirming high gene flow between these two subspecies. However, intermediate form was more distinct from both of them. It was also found that the genetic diversity of T. aestivum is obviously lower than that of Ae. tauschii accessions. Moreover, the level of genetic diversity for Gilan, Golestan and Mazanderan provinces was higher than for Ardebil, Ghazvin and Semnan provinces, suggesting that these regions may provide a readily available source of potentially useful variation for wheat improvement.  相似文献   

19.
We used AFLP analysis to explore the genetic relationship and diversity between and within 4 Mangifera species. We analyzed 35 accessions comprising 8 cultivars and 3 landraces of M. indica L., 11 landraces of M. odorata Griff., 7 landraces of M. foetida Lour., and 6 landraces of M. caesia Jack. Using 8 primer combinations produced a total of 518 bands, 499 (96.3%) of which were polymorphic among the 35 accessions. Clustering analysis showed that all 35 accessions were basically classified into 4 groups corresponding to the 4 Mangifera species. Our results indicate that the genetic relationship of these 4 Mangifera species based on AFLP analysis is in good agreement with their classification by classic methods. In addition, it was clearly revealed the genetic diversity between and within 4 Mangifera species. The findings obtained in this study are useful for the breeding in Mangifera species.  相似文献   

20.
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   

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