Enhancing salt tolerance in melon by exogenous application of melatonin and Ca 2+

摘要

Melatonin and Ca 2+ have been implicated in growth, development and stress responses in plants. Here, we report the effects of exogenous melatonin and Ca 2+ on growth, photosynthetic capacity, antioxidant potential and ion homeostasis in melon ( Cucumis melon L. cv. Yangjiaosu) seedlings under salt stress. It was observed that salt stress significantly inhibited growth in melon seedlings, while exogenous application of melatonin and Ca 2+ alleviated the inhibition. Further analysis showed that exogenous application of melatonin or Ca 2+ promoted photosynthetic rate and water use efficiency in salt-stressed melon seedlings. In addition, exogenous melatonin or Ca 2+ enhanced accumulation of Ca 2+ , but reduced accumulation of Na + in both leaves and roots of melon seedlings under salt stress. Furthermore, exogenous melatonin or Ca 2+ reduced oxidative damage, as demonstrated by decreased electrolyte leakage and MDA content, by stimulating activities of antioxidant enzymes, including SOD, POD, CAT and APX, in salt-stressed melon seedlings. Collectively, these results suggest that exogenous melatonin or Ca 2+ acts in the alleviation of salt stress by improving photosynthesis, maintaining ion homeostasis and elevating antioxidant capacity in melon seedlings. Our work also provides a case study and melatonin or Ca 2+ may serve as useful agent to relieve salt stress in agricultural production.