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.
Highlights
The genus Juglans is characterized by monoecious and heterodichogamous character, counting approximately 40 species, caterogised into three sections, Dioscaryon Dode, Cardocaryon Dode and Thyoscaryon Dode
Thirteen Random Amplified Polymorphic DNA (RAPD) primers used in present study produced 54 scorable fragments out of which 15 (27.78%) were polymorphic across 96 walnut genotypes
The number of polymorphic alleles found at each RAPD locus ranged from 0 to 7 with an average of 1.15 loci per primer
Summary
The genus Juglans is characterized by monoecious and heterodichogamous character, counting approximately 40 species, caterogised into three sections, Dioscaryon Dode, Cardocaryon Dode and Thyoscaryon Dode. Juglans regia L. belongs to Dioscaryon Dode Section and is the most economically important nut and oil species. India contributes 2% to the world’s total walnut production. Worldwide production of walnut has been rising speedily in recent years mainly in Asian countries due to its high nutritional value and antioxidant properties [3]. In India, walnuts are grown in Arunachal Pradesh, Himachal Pradesh, Uttarakhand and Jammu and Kashmir. J&K is the main centre for commercial walnut production in India and contributes around 98% of the country’s output and the state has been declared as the “Agri. Most walnuts produced for export by India are produced in this state. According to the United Nations Development Programme Special Unit for South-South Cooperation (UNDP SU/SSC), 63,000 hectares of Jammu and Received: July 28, 2019; Accepted: September 03, 2019; Published: September 10, 2019
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