Physiological and Biochemical Regulation Associated with Southern Blight Resistance in Mung Bean (Vigna radiata L.)

Abstract Mung bean (Vigna radiata L.) is an essential pulse crop valued for its nutritional and economic importance, yet southern blight disease caused by Sclerotium rolfsii severely threatens its physiology and productivity. Understanding the physiological responses associated with resistance characters is vital for improving stress resilience. The present study aims to characterise contrasting mung bean genotypes under artificial disease pressure to assess the agro-morphological parameters, antioxidant enzyme activities, and key biochemical constituents. Resistant mung bean genotypes were characterized by shorter stature, medium seed size, and reduced yield losses (<43%), whereas susceptible mung bean genotypes suffered >60% yield reduction with chlorophyll degradation and reduced antioxidant enzyme activity (particularly superoxide dismutase, peroxidase, and catalase (CAT)) being most severely impacted. This led to a reduction in photosynthetic efficiency and overall plant health. Biochemical profiling revealed that the resistant lines maintained higher CAT activity and carotenoid content, along with more stable chlorophyll levels, supporting efficient photosynthesis under stress conditions. Correlation and PCA analyses consistently linked CAT and carotenoids with survival and yield, establishing them as reliable biochemical markers of resistance. These findings not only identify novel resistant genetic resources but also provide key physiological markers for breeding programs aimed at developing durable, climate-resilient mung bean cultivars to strengthen food security.