Exogenous 24-epibrassinolide ameliorates tolerance to high-temperature by adjusting the biosynthesis of pigments, enzymatic, non-enzymatic antioxidants, and diosgenin content in fenugreek.

The current study highlights the influence of 24-epibrassinosteroid on enhancing tolerance to high-temperature and altering the diosgenin content in fenugreek. The EBR application under high-temperature stress, resulted in decreased malondialdehyde content and electrolyte leakage percentage compared to plants treated with high-temperature stress. The antioxidant activities rose under high-temperature stress and applying EBR compared to control. Exogenous EBR application possibly contributes in activating the NO, H 2 O 2 and ABA-dependent pathway, enhancing the biosynthesis of abscisic acid and auxin, and regulating the signal transduction pathways, which raises fenugreek tolerance to high-temperature. The SQS (8-fold), SEP (2.8-fold), CAS (11-fold), SMT (17-fold) and SQS (6-fold) expression, considerably increased following EBR application (8 μM) compared to control. Compared to control, when the short-term (6 h) high-temperature stress was accompanied by EBR (8 μM), a 6-fold increase in diosgenin content was achieved. Our findings highlight the potential role of exogenous 24-epibrassinolide in mitigating the high-temperature stress in fenugreek by stimulating the biosynthesis processes of enzymatic and non-enzymatic antioxidants, chlorophylls and diosgenin. In conclusion, the current results could be of utmost importance in breeding or biotechnology-based programs of fenugreek and also in the researches related to the engineering of the biosynthesis pathway of diosgenin in this valuable plant.