Synergistic effect of 24-epibrassinolide and salicylic acid on photosynthetic efficiency and gene expression in Brassica juncea L. under Pb stress.

Lead (Pb) has wide-ranging effects on various essential physiological processes in plants including seed germination, root/ shoot growth, photosynthetic efficiency, water status, and activities of enzymes. The effect of combined treatment of 24-epibrassinolide (10-7 M, EBL) and salicylic acid (1 mM, SA) on growth, photosynthetic attributes, and phenolic compounds in 30-, 60-, and 90-day-old plants of Brassica juncea L. under Pb stress (0.25 mM, 0.50 mM, and 0.75 mM) were studied. It was observed that Pb toxicity resulted in lowered growth and photosynthetic efficiency. The expressions of CHLASE, PSY, CHS, and PAL genes were altered. Presoaking treatment with the combination of EBL and SA for metal-stressed plants mitigated the adverse effects of metal stress by improving growth and levels of pigment and phenolic compounds.