Assessment of genetic diversity and population structure in two wild wheat species Aegilops cylindrica and Ae. crassa using microsatellite (SSR) markers

Aegilops genus is the main genetic source of variation for wheat breeders due to its breeding potential such as tolerance to both abiotic and biotic stresses. The main objective of this study were to evaluate the genetic diversity in 91 Aegilops accessions belonging to Ae. cylindrica and Ae. crassa using microsatellite (SSR) markers. A total of 49 fragments were amplified using 25 tested primers in which 48 products were polymorphic. The average values of polymorphic information content (PIC) and gene diversity (H), resolving power (Rp) and marker index (MI) were 0.26, 0.34, 1.29 and 0.51, respectively. The results of molecular variance analysis (AMOVA) showed the highest portion of genetic variance referred to inter-species compared to intra-species. Based on genetic variation parameters, the highest values of variation parameters were recorded in Ae. crassa than Ae. cylindrica accessions. Cluster analysis based on Jaccard’s coefficients and neighbor-joining algorithm grouped all investigated accessions into two main clusters, so that all accessions were clearly separated from each other. The result of principal coordinate analysis (PCoA) revealed that the first two components accounted for 64.98% of the total molecular variation. The PCoA-based biplot grouped all investigated accessions into two main groups. The result of population structure showed that all investigated accessions were recognized into five subpopulations, and FST index among them varied between 0.52 and 0.76 with an average of 0.76. In conclusion, these results indicated high genetic variation in Aegilops genus collection and could be used in Wheat improvement programs and other genetic studies like QTL and association mapping are recommended.