SSR-Based Assessment of Genetic Diversity in Iranin Walnut (Juglans regia L.)

Genetic variation assessment in plant gene pools is the first step in identifying, maintaining and conserving the genetic resources and also the basis for breeding programs. Molecular markers provide the important tools to evaluate the genetic diversity in native plants. In order to evaluate the genetic diversity of 62 Iranian walnut seedlings, 10 SSR primer pairs were used. The used SSR loci generated 53 alleles. The minimum and maximum number of alleles were for SSR loci WGA69, WGA71 (4 alleles) and WGA1 (7 alleles), respectively. The most value of observed heterozygosity was recorded by loci WGA276. All used SSR loci showed deviation from Hardy–Weinberg equilibrium (p≤0.01). UPGMA cluster analysis using Dice similarity coefficient classified four groups among 62 studied walnuts. Population structure analyses using Structure 2.3.1 software identified two possible groups (k=2). Membership coefficient matrix and Fst values of the each identified subgroup indicated no remarkable differentiation among the subgroups. In conclusion, information obtained from the current study could be useful for identification of the seedlings with enough genetic distance in walnut hybrid production programs to exploit the heterosis.