Studies on genetic diversity and variability in cluster bean [Cyamopsis tetragonoloba (L.) Taub.] genotypes through morphological and molecular characterization

The present study was carried out at the Horticulture Research Farm-I of the Department of Applied Plant Science (Horticulture), Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, to assess genetic diversity and variability among thirty cluster bean genotypes from Rajasthan and Punjab, India, using 21 ISSR markers. A total of 263 fragments were amplified, with 204 (77.57%) being polymorphic and 59 (22.43%) monomorphic. The number of polymorphic fragments per primer ranged from four (UBC-854) to fifteen (ISSR-5 and IS-7), with an average of 9.71. Polymorphism percentage varied from 58.33% (UBC-856) to 100% (UBC-820 and ISSR-8), with an average of 77.06%. The UPGMA tree constructed using Jaccard’s similarity coefficient revealed genetic relationships among the genotypes. Genetic diversity parameters, including an observed and effective number of alleles, Nei’s genetic diversity, and Shannon’s index, were 1.781, 1.462, 0.267, and 0.398, respectively. The total genotype diversity (Ht) was 0.2639, while within-population diversity (Hs) was 0.253. The mean coefficient of gene differentiation (Gst) was 0.041, with gene flow estimated at 11.549. Desirable genotypes identified based on both morphological and molecular characterization include IC-421834, IC-421855, IC-421828, IC-258087, IC-258092, and IC-369868. These genotypes hold the potential for breeding, gene mapping, and functional genomics to enhance cluster bean genetics.Keywords: Genetic diversity, variability, cluster bean, Cyamopsis tetragonoloba, ISSR, germplasm.