Drought-induced changes in the accumulation of boiling-soluble proteins (p40, GST, HSP90) in the grains of drought-tolerant and drought-sensitive cultivars of Triticum aestivum

Abstract

Approximately 70% of crop yield losses are caused by abiotic stresses, with drought being the most serious threat to crop production in many areas of the world. Plants have developed physiological and biochemical responses at multiple levels to allow them to grow and survive under drought stress. Among these, hydrophilins (BSPs, proteins soluble after boiling), representing 0.2% of the total genome, play an important role in the stress adaptation in plants. In this study, we examined the effect of drought on BSPs at different developmental stages of leaves and seeds in drought-tolerant (cv. PBW 175) and drought-susceptible (cv. PBW 621) cultivars of Triticum aestivum. The BSP profiles of seeds were outlined via SDS-PAGE followed by immunoblot analysis using anti-HSP (heat shock protein-90), anti-GST (glutathione S-transferases) and anti-p40 (protein 40). In SDS-PAGE profile, BSPs were detected in a genotype- and treatment-dependent manner. Notably, no BSPs were detected in shoots at any stage, whereas in seeds, many BSPs were detected, indicating organ-specific regulation of BSPs. In western blotting, the induced accumulation of protein bands Bsp40-51 and 59 and presence of differential band of BsHSP44 under drought conditions was observed only in tolerant cv. PBW 175, not in sensitive cv. PBW 621, indicating the roles of such proteins in drought-stress adaptation. BSPs were accumulated at different developmental stages in a cultivar- and stage-dependent manner. The induced expression of different BSPs under drought conditions in tolerant cv. PBW 175 implies the relevance of these BSPs under drought conditions. Notably, the different BSPs were also expressed under normal growth and developmental stages at 57 and 76 days post-anthesis, implying their key role in earlier stages and maturity of grain development.