Exploring genetic diversity of potential legume, Vigna angularis (Willd.) Ohwi and Ohashi through agro-morphological traits and SSR markers analysis

Adzuki bean, an underutilized grain legume, has a significant potential for enhancing food and nutritional security. The main obstacles to developing new cultivars and promoting the adzuki bean as a mainstream pulse crop are a lack of awareness about its potential and insufficient information on crop its genetic diversity. Here, we aimed to explore the untapped potential of adzuki bean germplasm by evaluating its agro-morphological traits and diversity at the molecular level and also to identify trait-specific germplasm by utilizing 100 adzuki bean accessions conserved in the Indian National Genebank. Significant variations was recorded for the morphological traits and identified promising accessions exhibiting desirable traits, such as early flowering (IC341945, EC340257 and EC340283), number of primary branches (IC341945 and IC469175), number of clusters per plant (EC000264, IC167611 and IC341939), number of pods per plant (IC469175, EC34264, EC000264), early maturity (EC340283; EC120460; IC341941) and number of seeds per pod (EC340240, IC455396 and IC341955). Molecular characterization of diverse accessions using 22 polymorphic SSR markers identified a total of 50 alleles, with a mean of 2.27 alleles per loci. The polymorphic information content (PIC) ranged from 0.03 to 0.46, indicating informativeness of markers in distinguishing diverse accessions. Further, the gene diversity among the accessions ranged from 0.03 to 0.57 with a mean of 0.19. Population structure analysis grouped the accessions into three genetic groups, supported by Principal Coordinate Analysis (PCoA) and a phylogenetic tree. Additionally, Analysis of Molecular Variance (AMOVA) confirmed a substantial genetic diversity among the adzuki bean accessions. Thus, the combined assessment of agro-morphological traits and molecular markers effectively distinguished adzuki bean accessions and provided valuable insights in understanding untapped variation at both morphological and molecular levels. The promising accessions identified in the study hold potential for integration into legume improvement programs through introgression breeding, contributing to the development of adzuki bean varieties with target trait.