Induction of antioxidant defenses by a low-dose cadmium priming alleviates heat stress in pigeon pea

Global warming has a devastating effect on the growth and productivity of plants. Pigeon pea, the second most important legume crop with high nutritional value, is at high risk due to high temperature exposure. Priming is an innovative agronomical application that can be used as a strategy to minimize the detrimental effects of any kind of stresses. In this study, we investigated how low dose of cadmium priming alleviates heat stress (HS) in pigeon pea seedlings. The results demonstrated that low dose of cadmium priming induced the expression of antioxidant systems and maintain a redox homeostasis. An enhanced level of antioxidant glutathione, and antioxidative enzymes (SOD, APX, and GR) were observed in Cd+HS leaf (40 μM Cd priming followed by exposure to HS, 42°C) as compared to the HS leaf. Moreover, a reduction in hydrogen peroxide (H2O2) and oxidized glutathione (GSSG) content was also noticed in Cd+HS leaf. The GSH/GSSG ratio, which was indicative of the redox state in the plant system, was also high in Cd+HS leaf as compared to HS leaf. Thus, the priming of pigeon pea seeds with low dose Cd alleviates HS by elevating antioxidant defenses, ultimately protecting pigeon pea seedlings against HS.