Jasmonic acid regulates various abiotic stress responses but its role in regulation of copper (Cu) homeostasis has been poorly studied. This present study was conducted to explore the potential of jasmonic acid (JA) to enhance copper (Cu) tolerance in Cajanus cajan seedlings in terms of photosynthetic pigments, osmolytes and antioxidants. Seeds treated with different concentration (0, 1 µM, 1 nM and 1 pM) of JA raised in toxic concentration of Cu for 15 days were taken for investigation. Results indicate that Cu stress led to the decreased growth in terms of shoot length, fresh and dry weight. Cu stress also increased Cu accumulation, lipid peroxidation, deteriorated chlorophyll b as well as carotenoids. Cu stress also diminished total proteins, vitamins A, C and B2, and peroxidase activity which led to the deteriorated plant growth and metabolism. Seed priming treatment of JA on the other hand improved the protein content, sugar content and vitamins indicating the potential of JA for Cu stress tolerance. The JA supplementation to Cu stressed seedlings improved Cu tolerance of C. cajan to significant level.
Key words: Oxidative stress, lipid peroxidation, antioxidants, osmolyte, pigeon pea.