24-Epibrassinolide (24-EBL) Mediated Regulation of Chlorophyll, Protein and Osmolyte Metabolism in Wheat (Triticum aestivum L.) Genotypes under Heat Stress
Gali Suresh
Department of Botany and Plant Physiology, Chaudhary Charan Singh Haryana Agricultural University (CCS HAU), Hisar, 125004, India.
Priyanka Sharma *
Department of Crop Physiology, Assam Agricultural University (AAU), Jorhat, 785013, Assam, India.
Pravin Prakash
Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), Varanasi, 221 005, Uttar Pradesh, India.
Basant Kumar Dadrwal
*
Department of Plant Physiology, Sri Karan Narendra Agriculture University, Jobner, 302024, Rajasthan, India.
Asha Kumari
ICAR-Indian Agricultural Research Institute (ICAR-IARI), Gauria Karma, Hazaribagh, 825405, Jharkhand, India.
Madisetty Sai Venkata Ravi Teja
Department of Crop Physiology, University of Agricultural Sciences (GKVK), Bengaluru, 560065, Karnataka, India.
*Author to whom correspondence should be addressed.
Abstract
High temperature stress poses a major threat to wheat productivity by reducing chlorophyll stability, impairing protein metabolism, and altering osmolyte accumulation. Brassinosteroids, a class of plant steroidal hormones, are known to enhance plant tolerance against environmental stresses through biochemical regulation. In the present study, the effect of foliar-applied 24-epibrassinolide (24-EBL) at different concentrations (0.01, 0.02, and 0.03 mM) was investigated in two contrasting wheat (Triticum aestivum L.) genotypes HUW-510 (heat tolerant) and HUW-468 (heat susceptible) grown under field conditions. Heat stress led to significant declines in chlorophyll content, nitrate reductase activity, and protein levels, while osmolytes such as proline and soluble sugars accumulated as protective responses. Exogenous application of 24-EBL, particularly at 0.02 mM, effectively mitigated these negative impacts by maintaining higher chlorophyll levels, enhancing nitrate reductase activity, improving protein stability, and promoting osmolyte accumulation. The tolerant genotype (HUW-510) exhibited stronger biochemical resilience compared to the susceptible genotype (HUW-468). These findings demonstrate that 24-EBL plays a crucial role in alleviating heat stress-induced biochemical impairments in wheat, offering a potential strategy for sustaining productivity under future climate scenarios.
Keywords: 24-epibrassinolide, chlorophyll, heat stress, nitrate reductase, proline, protein, soluble sugars, wheat