Beneficial Roles of Melatonin on Redox Regulation of Photosynthetic Electron Transport and Synthesis of D1 Protein in Tomato Seedlings under Salt Stress.
Beneficial Roles of Melatonin on Redox Regulation of Photosynthetic Electron Transport and Synthesis of D1 Protein in Tomato Seedlings under Salt Stress.
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DOI：
10.3389/fpls.2016.01823
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发表时间：
2016
影响因子：
5.6
通讯作者：
Zou Z
中科院分区：
文献类型：
--
作者：
Zhou X;Zhao H;Cao K;Hu L;Du T;Baluška F;Zou Z
褪黑素在保护植物免受各种形式的非生物胁迫方面具有重要作用。褪黑激素介导的光合作用机制的分子机制尚未完全解决。本研究探讨了外源褪黑素对盐诱导的番茄幼苗光合机制光反应组分损伤的影响。结果表明，在盐胁迫条件下，褪黑素预处理有助于维持植株生长和净光合速率。褪黑素预处理增加了光系统II的有效量子产率（ΦPSII）、光化学猝灭系数（qP）和生理盐水条件下PSII中心“开放”（qL）的比例。通过这种方式，减轻了光系统II （PSII）中光合电子传递链（PET）的损伤。此外，褪黑素预处理通过维持D1蛋白的可用性来促进PSII的修复，否则D1蛋白会因盐度而降低。研究了叶绿体TRXs和PRXs的ROS水平和基因表达。盐胁迫导致活性氧（ROS）水平升高，褪黑激素可以缓解这一现象。盐胁迫下番茄叶片中PRXs和TRXf的表达量下降，TRXm1/4和TRXm2的表达量上升。褪黑素预处理促进了TRXf的表达以及TRXf和TRXm基因产物的丰度，但对PRXs的表达没有影响。综上所述，褪黑素提高了盐胁迫下番茄幼苗的光合活性。其机制可能是：(1)褪黑激素控制ROS水平，防止盐胁迫引起的ROS损伤性升高。(2)褪黑素促进PET和D1蛋白合成的恢复，从而增强光合活性对盐度的耐受性。(3)褪黑素诱导TRXf的表达，调节TRXf和TRXm基因产物的丰度，促进光合机制光反应部分的修复。
Melatonin is important in the protection of plants suffering various forms of abiotic stress. The molecular mechanisms underlying the melatonin-mediated protection of their photosynthetic machinery are not completely resolved. This study investigates the effects of exogenous melatonin applications on salt-induced damage to the light reaction components of the photosynthetic machinery of tomato seedlings. The results showed that melatonin pretreatments can help maintain growth and net photosynthetic rate (PN) under salt stress conditions. Pretreatment with melatonin increased the effective quantum yield of photosystem II (ΦPSII), the photochemical quenching coefficient (qP) and the proportion of PSII centers that are “open” (qL) under saline conditions. In this way, damage to the photosynthetic electron transport chain (PET) in photosystem II (PSII) was mitigated. In addition, melatonin pretreatment facilitated the repair of PSII by maintaining the availability of D1 protein that was otherwise reduced by salinity. The ROS levels and the gene expressions of the chloroplast TRXs and PRXs were also investigated. Salt stress resulted in increased levels of reactive oxygen species (ROS), which were mitigated by melatonin. In tomato leaves under salt stress, the expressions of PRXs and TRXf declined but the expressions of TRXm1/4 and TRXm2 increased. Melatonin pretreatment promoted the expression of TRXf and the abundances of TRXf and TRXm gene products but had no effects on the expressions of PRXs. In summary, melatonin improves the photosynthetic activities of tomato seedlings under salt stress. The mechanism could be that: (1) Melatonin controls ROS levels and prevents damaging elevations of ROS caused by salt stress. (2) Melatonin facilitates the recovery of PET and D1 protein synthesis, thus enhancing the tolerance of photosynthetic activities to salinity. (3) Melatonin induces the expression of TRXf and regulates the abundance of TRXf and TRXm gene products, which may facilitate repair of the light reaction parts of the photosynthetic machinery.
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