Association analysis and evaluation of genetic diversity in wheat genotypes using SSR markers

A population of 105 wheat genotypes (including 94 hexaploid and 11 tetraploid genotypes) was used to determine genetic diversity. Samples were grown based on the randomized complete block design with three replications under salinity stress (120 mM NaCl (and control (10 mM NaCl (conditions. Morpho-physiological traits associated with tolerance of salinity at the seedling stage were recorded. The results of the analysis of variance showed that there were significant differences between genotypes in all studied traits, except K⁺/Na⁺ ratio. The amount of potassium content of leaves and roots in control was higher than salt stress conditions. Salinity significantly decreased all traits measured except Na⁺ concentration in root and shoot and leaf stomata conduction. A total of 12 SSR (simple sequence repeats) markers were assessed for the existence of polymorphism between genotypes. The highest Nei (Nei 1973) gene diversity was observed for gwm410 (0.72) and gpw2181 (0.71) markers, and PIC (polymorphic information content index) values ranged from 0.2 to 0.67. According to PIC, only six markers were informative during this study. These markers could be more efficient in displaying the genotypic differentiation of the near-wheat species as they showed the highest genetic diversity. Simple regression analysis showed that barc212 marker had the most significant relationship with root dry weight, leaf moisture and stomatal conductance (at 0.01 significant level). The gpw2181 marker showed a significant correlation with different traits under stress conditions. It was suggested that this marker could be used for marker-assisted selection to improve salt stress tolerance of wheat.