Unraveling multi-trait genetic control of drought tolerance and yield stability in black gram via genome-wide association analysis

Drought stress is a major abiotic constraint limiting productivity of black gram ( Vigna mungo L.) in rainfed agro-ecosystems, necessitating the identification of drought-resilient genotypes and associated adaptive traits. In the present study, a genome-wide association approach integrating morpho-physiological, biochemical and molecular analyses was employed to unravel the genetic architecture of drought tolerance, grain yield and its component traits. A panel of 60 diverse genotypes were evaluated under control and water-stress conditions using a randomized complete block design. Significant genotypic, treatment and genotypic × treatment variances were observed for most traits, indicating substantial genetic variability and differential drought responses. Drought stress caused marked reductions in seed yield, plant height, chlorophyll content, relative water content, membrane stability index, NDVI and canopy temperature depression, while proline and total soluble sugar contents increased substantially, reflecting osmotic adjustment mechanisms. Among genotypes IC546466, IPU9612, IPU243, IC331232 and IC426766 exhibited superior yield stability and physiological resilience under stress. Genotyping with 130 SSR markers revealed high allelic diversity (389 alleles; mean PIC = 0.57) and clear population stratification into two subpopulations. Genome-wide association analysis identified 28 and 40 significant marker-trait associations under control and drought stress conditions respectively, highlighting their potential utility in marker-assisted selection. Overall, these associations underscore the critical role of intrinsic tolerance mechanisms and cumulative traits in drought tolerance, identifying promising genotypes and SSR markers to accelerate breeding programs for drought-resilient crops.