Genetic Diversity Analysis of Walnut (Juglans regia L.) from Kashmir Valley Using RAPD and ISSR Markers

Abstract

Walnut (Juglans regia) is one of the most essential nutritive and economic nut crops. Genetic diversity analysis of 96 walnut genotypes from Kashmir was done using 13 RAPD and 19 ISSR markers. RAPD diversity analysis revealed 27.78% polymorphism while as ISSR analysis showed 93.05% of polymorphic bands. Jaccards similarity co-efficient ranged from 0.78 to 1 with an average of 0.91 for RAPD and 0.22 to 0.85 with an average of 0.58 for ISSR markers and 0.59 to 0.92 with an average of 0.74 for combined data. Cluster analysis using UPGMA by RAPD and ISSR markers obviously revealed distinct diversity between genotypes. The dendrogram constructed from the combination of RAPD and ISSR markers categorized the 96 genotypes into one major cluster and five minor clusters. Effective number of alleles (Ne), Nei’s gene diversity (H) and Shannon’s Information index (I) of 96 samples were 1.12, 0.08 and 0.12 respectively for RAPD data and 1.48, 0.29 and 0.44 for ISSR data respectively. Positive correlation (r=0.11) was observed between RAPD and ISSR markers using the Mantel test and thus supporting the validity of the dendrogram. The high number of alleles and a broad range of genetic diversity were observed among all the genotypes, accounting them as potential candidates for selective breeding for particular traits and expanding the genetic base. Based on our results, RAPD and ISSR analysis can be used for the characterization and categorizing of walnut genotypes and indicate that Jammu and Kashmir has a significant genetic diversity pool and rich genetic variance of walnuts.