Effect of heat stress on seed protein quality in mungbean [Vigna radiata (L.) Wilczek]

Abstract Abiotic and biotic stresses impair the productivity of agricultural crops. Among abiotic stresses, the higher temperature (i.e., heat stress) is unfavourable for plant growth and development. In recent years, the mungbean [Vigna radiata (L.) Wilczek] demand has been increasing, which can satisfy human protein requirements. However, its productivity and quality are negatively impacted by heat stress due to climate change. This requires a broadening scope of mungbean adaptation to warmer climates. Hence, the objective of this study was to assess the effects of heat stress on various mungbean genotypes for their seed protein characteristics (total seed protein content, proportion of four protein fractions, and electrophoretic patterns on SDS‐gels). The 13 mungbean genotypes were grown under normal and heat‐stressed conditions by sowing seeds at two different times, that is, the normal sowing time in the last week of March and late sowing in the last week of April in the experimental plots. In late‐sown plants, the total seed proteins decreased by 4.1% to 9.3%. In addition, the relative proportion of glutelins and prolamins increased significantly while globulins and albumins decreased at high temperatures. Moreover, the intensity of polypeptides decreased under high temperatures. In our studies, some polypeptides appeared, and others disappeared in late‐sown genotypes. The disappearance of bands reveals a higher rate of protein degradation than synthesis under heat stress. The detrimental effects of heat stress on seed protein characteristics studied were more prominent in MH 318, IPM 02‐3 and PM‐5 and less noticeable in MH 125, MH 421 and PDM 139 genotypes.