Comparative assessment of wheat landraces from AWCC, ICARDA and VIR germplasm collections based on the analysis of SSR markers

About 16,000 bread wheat landraces from three significant gene banks were amalgamated into a virtual collection. Each of the landraces was characterized by collection site coordinates (latitude and longitude). Climatic and edaphic attributes were estimated for each collection site. A core collection of 512 accessions and a drought targeted subset of landraces (from dry environments) of 479 accessions were selected based on all available information. In total 976 bread wheat landraces maintained in AWCC (187 accessions), ICARDA (338) and VIR (451) originated from 675 collection sites of 48 countries over the world were compared on the structure of 13 SSR loci mapped on different wheat chromosomes. Cluster analysis of the data was applied for evaluation of genetic diversity inside the two subsets of landraces. Four major and six minor clusters were identified on the dendrogram constructed by the analysis of 269 different SSR alleles. Landraces from the same country largely had a tendency for grouping into one of the clusters. For instance, the majority of landraces from Russia and Ukraine combined in cluster 1, from Turkey – in cluster 2, Afghanistan and Iran – 3, Kazakhstan – 4. Although there are no remarkable differences on the frequency of SSR alleles, accessions collected in dry areas are seldom in cluster 1 but more common in cluster 3, where mainly landraces from countries with dry climate are grouped. Peculiarities of geographical distribution of different SSR alleles and representation of ones in landraces from the three significant gene banks are discussed.