Exogenous Melatonin Confers Salt Stress Tolerance to Watermelon by Improving Photosynthesis and Redox Homeostasis.
Exogenous Melatonin Confers Salt Stress Tolerance to Watermelon by Improving Photosynthesis and Redox Homeostasis.
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DOI：
10.3389/fpls.2017.00295
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发表时间：
2017
影响因子：
5.6
通讯作者：
Zhang X
中科院分区：
文献类型：
--
作者：
Li H;Chang J;Chen H;Wang Z;Gu X;Wei C;Zhang Y;Ma J;Yang J;Zhang X
褪黑激素是一种多效性信号分子，在调节植物生长发育和对环境胁迫的反应中发挥重要作用。由于一些植物已经研究了外源褪黑激素对盐胁迫的影响，褪黑激素介导的盐胁迫耐受性在其他植物中的潜在机制仍然是未知的。在这项研究中，褪黑激素对叶片光合作用和氧化还原稳态在西瓜盐胁迫（300 mM NaCl）沿着不同剂量的褪黑激素（50，150，500 μM）预处理的影响进行了研究。NaCl胁迫抑制了西瓜幼苗光合作用，增加了叶片活性氧的积累和膜伤害。然而，褪黑激素预处理根缓解NaCl诱导的光合速率下降和氧化胁迫的剂量依赖性的方式。褪黑激素对光合作用的保护作用与抑制气孔关闭和改善光系统II的光能吸收和电子传递密切相关，而褪黑激素对氧化胁迫的降低则归因于其改善氧化还原稳态和增强抗氧化酶的活性。这项研究揭示了褪黑激素在盐胁迫缓解中的关键作用，因此可以在西瓜栽培中的盐分管理。
Melatonin, a pleiotropic signal molecule, has been shown to play important roles in the regulation of plant growth, development, and responses to environmental stresses. Since a few species have been investigated to unveil the effect of exogenous melatonin on salt stress, the underlying mechanism of melatonin-mediated salt stress tolerance in other plant species still remains largely unknown. In this study, the effects of melatonin on leaf photosynthesis and redox homeostasis in watermelon were examined under salt stress (300 mM NaCl) along with different doses of melatonin (50, 150, and 500 μM) pretreatment. NaCl stress inhibited photosynthesis and increased accumulation of reactive oxygen species and membrane damage in leaves of watermelon seedlings. However, pretreatment with melatonin on roots alleviated NaCl-induced decrease in photosynthetic rate and oxidative stress in a dose-dependent manner. The protection of photosynthesis by melatonin was closely associated with the inhibition of stomatal closure and improved light energy absorption and electron transport in photosystem II, while the reduction of oxidative stress by melatonin was attributed to the improved redox homeostasis coupled with the enhanced activities of antioxidant enzymes. This study unraveled crucial role of melatonin in salt stress mitigation and thus can be implicated in the management of salinity in watermelon cultivation.