Study of Genetic Structure and Diversity of Iranian Wheat Lines and Cultivars using SSR Markers

Genetic improvement of crop plants such as wheat, relies on genetic diversity. In the current investigation, the genetic diversity of 99 wheat lines and 49 cultivars were assessed using 20 SSR primers. Out of the primers used, 19 were polymorphic among studied lines and cultivars and a total of 67 alleles were amplified. The number of alleles per locus ranged from 1 (Xgwm44) to 7 (Xgwm47), with a mean value of 3.5. The mean of expected heterozygosity (He) ranged from 0.71 (Xgwm149) to 0.27 (Xgwm469). The mean of polymorphism information content (PIC) and the maximum value of Shannon’s information index (I) were 0.52 and 0.88 respectively. The number of alleles (Na), Shannon’s information index (I) and mean of expected heterozygosity (He), for lines were slightly more than those of cultivars. Average of gene differentiation coefficients (Fst) and gene flow (Nm) for all primers were 0.067 and 6.96 respectively. Analysis of molecular variance (AMOVA) revealed a higher level of genetic variation within lines + cultivars (89%) compared to among lines and cultivars (11%). Cluster analysis using UPGMA method and simple matching coefficients placed the lines and cultivars in five groups. Similarity coefficients ranged from 0.40 to 1 with a mean value of 0.70. Some cultivars with the same geographic origin were located in the same cluster. The high level of genetic similarity detected in cultivars may demonstrate the narrow genetic base of Iranian wheat germplasm. However, according to the genetic distance between different groups, lines in divergent groups could be potentially used as parents in wheat breeding programs.