首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 62 毫秒
1.
Genetic diversity among some important Syrian wheat cultivars was estimated using Amplified Fragment Length Polymorphism (AFLP) markers. Five Triticum aestivum L. and 10 Triticum turgidum ssp. durum were analyzed with 11 EcoRI–MseI primer pair combinations. Of the approximately 525 detected AFLP markers, only 46.67% were polymorphic. Cluster analysis with the entire AFLP data divided all cultivars into two major groups reflecting their origins. The first one contained T. aestivum L. cultivars, and the T. turgidum ssp. durum cultivars and landraces were grouped in the second. Narrow genetic diversity among all cultivars was detected with an average genetic similarity of 0.884. The lowest similarity index (0.9) was found between Cham5 and Hamary (durum wheat), whereas this value was 0.93 between Salamony and Bouhouth 4 (T. aestivum L.). The narrow genetic diversity level indicates that these genotypes could be originated from the same source. AFLP analysis provides crucial information for studying genetic variation among wheat cultivars and provides important information for plant improvement.  相似文献   

2.
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   

3.
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   

4.
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   

5.
  相似文献   

6.
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   

7.
The genetic diversity of a subset of the Ethiopian genebank collection maintained at the IPK Gatersleben was investigated applying 22 wheat microsatellites (WMS). The material consisted of 135 accessions belonging to the species T. aestivum L. (69 accessions), T. aethiopicum Jacubz. (54 accessions) and T. durum Desf. (12 accessions), obtained from different collection missions. In total 286 alleles were detected, ranging from 4 to 26 per WMS. For the three species T. aestivum, T. aethiopicum and T. durum on average 9.9, 7.9 and 7.9 alleles per locus, respectively, were observed. The average PIC values per locus were highly comparable for the three species analysed. Considering the genomes it was shown that the largest numbers of alleles per locus occurred in the B genome (18.4 alleles per locus) compared to A (10.1 alleles per locus) and D (8.2 alleles per locus) genomes. Genetic dissimilarity values between accessions were used to produce a dendrogram. All accessions could be distinguished, clustering in two large groups. Whereas T. aestivum formed a separate cluster, no clear discrimination between the two tetraploid species T. durum and T. aethiopicum was observed.  相似文献   

8.
In order to evaluate and compare the germplasm resources of wheat in Tibet, we analyzed the genetic diversity of 136 Triticum aestivum ssp. tibetanum Shao and 119 Tibetan wheat landraces (Triticum aestivum L.) by using Intron-Splice Junction (ISJ) primers. The results showed that polymorphism of PCR products were obtained by 33 primer combinations, which accounted for 11% of the 300 primer combinations produced by 26 ISJ primers. A total of 333 stable bands can be amplified from the T. aestivum ssp. tibetanum Shao and 243 bands were polymorphic, which accounted for 72.9% of the total bands. Tibetan wheat Landraces produced 316 stable bands, of which 197 bands were polymorphic. The polymorphic bands accounted for 62.34% of the total bands produced from Tibetan wheat landraces. The genetic diversity of T. aestivum ssp. tibetanum Shao was higher than that of Tibetan wheat landraces in Tibet, suggesting that T. aestivum ssp. tibetanum Shao can be used as important genetic resource for the breeding and genetic improvement of wheat in Tibet. Matrix (1, 0) was generated according to the presence or absence of the bands produced from a particular wheat accession. Clustering and principle coordinates analysis showed that T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces were divided into two groups. We conclude that high polymorphisms produced by ISJ primers can reflect the genetic diversity between T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces.  相似文献   

9.
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   

10.
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   

11.
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   

12.
Carbon isotope discrimination (Δ) has been proposed as physiological criterion to select C3 crops for yield and water use efficiency. The relationships between carbon isotope discrimination (Δ), water use efficiency for grain and biomass production (WUEG and WUEB, respectively) and plant and leaf traits were examined in 20 Iranian wheat genotypes including einkorn wheat (Triticum monococcum L. subsp. monococcum) accessions, durum wheat (T. turgidum L. subsp. durum (Desf.) Husn.) landraces and bread wheat (T. aestivum L. subsp. aestivum) landraces and improved cultivars, grown in pots under well-watered conditions. Carbon isotope discrimination was higher in diploid than in hexaploid and tetraploid wheats and was negatively associated with grain yield across species as well as within bread wheat. It was also positively correlated to stomatal frequency. The highest WUEG and grain yield were noted in bread wheat and the lowest in einkorn wheat. Einkorn and bread wheat had higher WUEB and biomass than durum wheat. WUEG and WUEB were significantly negatively associated to Δ across species as well as within bread and durum wheat. The variation for WUEG was mainly driven by the variation for harvest index across species and by the variation for Δ within species. The quantity of water extracted by the crop, that was closely correlated to root mass, poorly influenced WUEG. Environmental conditions and genetic variation for water use efficiency related traits appear to highly determine the relationships between WUEG and its different components (water consumed, transpiration efficiency and carbon partitioning).  相似文献   

13.
Wheat (Triticum spp.) landrace populations in Ethiopia are mostly species mixtures. However, no quantitative data is available with regard to their species components. We studied here 32 wheat landrace populations originating from two regions (Bale and Wello). A total of 2559 individual plants, 45–110 plants representing each population, were classified into their species components. Five tetraploid (2n = 4x = 28) and one hexaploid (2n = 6x = 42) wheat species were found in mixtures of varying proportions. These included the tetraploids Triticum durum Desf., Triticum turgidum L., Triticum aethiopicum Jakubz., Triticum polonicum L., Triticum dicoccon Schrank and the hexaploid Triticum aestivum L. Also found, however in a rare frequency, in two populations from Wollo was T. durum Desf. convar. durocompactoides Flaksb. (Triticum pyramidale Percival), which is a very dense spiked durum. Discriminant analysis using seven qualitative traits revealed 91.5% correct classification of the wheat species, beak awn and awn length with the most significant importance. Single species were found in eight of the populations; six were for T. durum and two for T. aethiopicum. Two to three species-combinations were the most frequent; a maximum of four species was recorded in one population. The highest diversity index (H′) observed was 0.44. T. durum was the most predominant species. The hexaploid T. aestivum was found in nine of the Wollo populations and, in one population, its frequency reached up to 35.5%. On altitudinal basis, no clear trend of clinal variation was observed both from the frequency distributions and H′ estimates. The results confirmed that Ethiopian wheats, despite the morphological overlaps, could be classified into their species components with high degree of certainty. For the future, therefore, genetic diversity estimations should be dissolved into their species components for more expeditious utilization and conservation of this important genetic resource.  相似文献   

14.
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   

15.
In the last few years, the renewed interest for emmer wheat (Triticum dicoccon Schrank) in Italy has stimulated breeding programs for this crop releasing improved genotypes obtained not only by selection from landraces, but even by crosses with durum wheat (Triticum durum Desf.) varieties. The purpose of this work has been to uncover the genetic make-up of some emmer × durum derivatives, specifically by comparing the differences from their parents. Genetic diversity of advanced breeding lines and varieties derived from a durum × emmer cross has been evaluated on the basis of AFLP and SSR markers in comparison with the corresponding emmer and durum wheat parent for addressing the seminal question of how much ‘wild’ variation remains after selection for agronomic type.  相似文献   

16.
Bread wheat Triticum aestivum L. possesses a genetic variation for the ability to survive and reproduce under salt stress conditions. Durum wheat (T. durum Desf.) is in general more sensitive in comparison to bread wheat, however, exceptions can be found showing the same extent of salt tolerance. Endemic wheats in general are characterised by a high adaptability to their environment. The level and variability of salt tolerance were assessed in a germplasm collection of 144 winter and spring wheat accessions from Georgia comprising Triticum aestivum L., T. durum Desf., T. dicoccon Schrank, T. polonicum L. and Georgian endemics: T. carthlicum Nevski, T. karamyschevii Nevski, T. macha Dekapr. et Menabde, T. timopheevii (Zhuk.) Zhuk. and T. zhukovskyi Menabde et Ericzjan. The accessions were tested for salt tolerance at the germination stage. Large variability in salt tolerance within the Georgian germplasm was found among the different wheat species. The endemic hexaploid winter wheat T. macha and the endemic tetraploid wheat T. timopheevii were among the most tolerant materials, thus presenting promising donors for salt tolerant traits in future breeding efforts for salinity tolerance in wheat.  相似文献   

17.
Assessing genetic erosion has been suggested as the first priority in any major effort to arrest loss of genetic diversity. In Ethiopia, although it is generally accepted that significant amount of genetic erosion has occurred and is still occurring, there is little data on its amount and extent. Thus, this study is conducted to quantify the extent of genetic erosion in Ethiopian tetraploid wheat landraces and to identify major causes of genetic erosion. To this end, a field survey of 126 farmers, randomly selected over five districts in eastern, south-eastern and central highlands of Ethiopia during 2001/2002 and 2002/2003 main cropping seasons was undertaken. Questioner was used to collect primary data from farmers who are potentially rich sources of information on genetic erosion at the variety level. Additional data were collected through key informant interviewing. Moreover, resampling was made from Tulo, Chiro and Harar Zuriya districts in eastern Ethiopia. Analysis of history profiles from primary and secondary data indicated a reduction in the use of local varieties over years. Triticum polonicum and T. turgidum are becoming very localized, and therefore, they are under greater threat of extinction. Using the calculation scheme: gene erosion=100%−gene integrity, i.e., the still extant landraces, genetic erosion was calculated for the three different areas where resamplings were made. Genetic erosion of 100% was observed both in T. durum and T. dicoccon in Tulo district. Likewise, genetic erosion of 85.7, 100 and 77.8%, respectively, was calculated for T. durum, T. turgidum and T. dicoccon in Chiro district. In Harar Zuriya, a genetic erosion of 88.9% for T. durum and 100% both in T. turgidum and T. dicoccon was detected. Number of farmers growing landraces of tetraploid wheats drastically decreased in all surveyed areas in the past decades. Displacement of landraces by other crops was the prominent factor for ending landrace cultivation. Farmers’ preference to yield potential and cash crops subsequently reduced the chance of maintaining landraces. Institutional factors like access to credit and the extension advice have influenced farmers’ decision regarding cultivar choice. In all surveyed areas, the most important initial source of seed of improved wheat varieties is the seed credit from the Ministry of Agriculture which uses a ‘plant now, pay later’ scheme to promote the distribution of improved varieties and fertilizers. The problem of genetic erosion through inappropriate maintenance of ex situ collections was also recognized and discussed.  相似文献   

18.
In several regions of Italy as well as other parts of southern Europe, the heterogeneity of the land, the climate and the soil favour the survival in cultivation of a large number of landraces specifically adapted to local conditions. Knowledge on the level and distribution of their genetic variation can help to develop appropriate strategies, in order to suistainably manage in situ these germplasm resources at risk of genetic erosion. C. annuum is an herbaceous diploid species and is considered to be self-pollinating, although different rates of out-crossing have been recorded. We used random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers to assess genetic diversity within and between five populations of a landrace of Capsicum annuum L., grown in a limited area in north-west Italy and locally known as Cuneo pepper. Partitioning the genetic variation with Shannon's diversity index revealed that 41.6% occurred between and 58.4% within populations. Analogous results were obtained when the analysis was based only on RAPD or AFLP markers. However, AFLP was more reliable, since a lower range of variation was observed among primer combinations in detecting the two components of genetic variation. Notwithstanding the rather high level of within genetic variation detected, the five populations were clearly differentiated and differed in the frequency of alleles exclusive and/or present at very low frequencies. Our results show the need for accurate estimation of allele frequencies, in order to identify populations to which priority should be given for dynamic conservation of landraces.  相似文献   

19.
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   

20.
The genetic diversity of high and low molecular weight glutenin subunits of 63 durum wheat landraces from different geographical regions in the Mediterranean Basin was studied using SDS-PAGE. Great variability in glutenin composition was found, with 42 high and low molecular weight glutenin haplotypes, 20 allele combinations at the HMW-GS loci, and 18 at the LMW-GS. All five possible LMW models were detected in all Mediterranean regions. Rare alleles were found at Glu-B1 locus in high frequencies and a priori related alleles to grain quality were also observed. Global genetic diversity index was relatively high (0.67); it ranged from 0.33 to 0.66. Cluster analysis on the frequency patterns of origins grouped genotypes following a geographical structure. Rogers’ distance coefficient on frequency pattern for each region of origin showed two germplasm pools with distinct quality profiles, where South West Asian landraces were very different from the landraces of other Mediterranean areas. The relationship between different regions of origin is discussed and two possible ways of introduction of wheat in the Iberian Peninsula (N Africa and SE Europe) are hypothesized. The use of Mediterranean durum wheat landraces as source of genetic variability for grain quality improvement is highly recommended.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号