Morphological, physiological and biochemical insights into heat stress response in mungbean (Vigna radiata (L.) Wilczek)

Abstract

Mungbean (Vigna radiata) is a warm-season legume crop and plays a crucial role in food and nutritional security in South and Southeast Asia. Being a legume crop, it also plays a role in ecosystem sustainability. However, crop cultivation is facing an imminent threat amid the recent rise in global temperature. The optimum temperature range for mungbean cultivation is 28–35°C, although some genotypes can grow well even up to 40°C of atmospheric temperature. Therefore, in this study, 1515 mungbean accessions were initially screened for heat-responsive morphological and physiological traits to identify superior genotypes. From this preliminary screening, 75 diverse accessions were selected for a more comprehensive evaluation of heat-responsive traits. Subsequently, 32 promising genotypes were chosen for an in-depth analysis of enzymatic and nonenzymatic antioxidant activities under both heat-stressed and non-stressed conditions. Certain genotypes, namely IC76475, IC418452 and IC489062, were superior for multiple heat stress-responsive traits. The phenotypic expression of these genotypes was further validated under controlled environmental conditions. Their heat stress tolerance was confirmed through RT-PCR analysis of key candidate genes (GmAKT2, Cu/ZnSOD, APX1 and CAT1). The findings from this study will aid in developing mungbean cultivars with enhanced tolerance to heat stress.