Brassinosteroids accelerate recovery of photosynthetic apparatus from cold stress by balancing the electron partitioning, carboxylation and redox homeostasis in cucumber
Brassinosteroids accelerate recovery of photosynthetic apparatus from cold stress by balancing the electron partitioning, carboxylation and redox homeostasis in cucumber
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DOI：
10.1111/j.1399-3054.2012.01696.x
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发表时间：
2013-05-01
影响因子：
6.4
通讯作者：
Yu, Jing-Quan
中科院分区：
文献类型：
--
作者：
Jiang, Yu-Ping;Huang, Li-Feng;Yu, Jing-Quan
本研究旨在探讨油菜素内酯（BR）在保护黄瓜（Cucumis sativus）光合机构免受冷诱导损伤中的作用。在10/7 ℃冷却后，在强光（HL）和弱光（LL）下的恢复诱导了CO2同化的不可逆抑制，光系统I（PSI）的光抑制以及卡尔文循环和抗坏血酸（阿萨）-还原型谷胱甘肽（GSH）循环酶活性的抑制，随后是H2 O2和丙二醛的积累。然而，冷诱导的光抑制在PSII完全恢复在LL，但不是在HL。同时，HL恢复增加了O2依赖性旁路途径的电子通量[Ja（O2依赖性）]。叶面施用24-表油菜素（EBR）可加速PSII光抑制的恢复，但不加速PSI的恢复。EBR还显著增加了CO2同化、卡尔文循环酶活性和电子流到碳还原[Je（PCR）]，同时降低了Ja（O2依赖性）;同时EBR增加了AsA-GSH循环酶活性和细胞氧化还原状态。然而，EBR对植物恢复的积极影响只在HL观察到，但不是LL。这些结果表明，BR通过激活卡尔文循环中的酶和提高抗氧化能力，加速了HL光合机构的恢复，从而减轻了恢复过程中的光氧化胁迫和对植物生长的抑制。
The aim of this study was to examine the role of brassinosteroids (BRs) in protecting the photosynthetic apparatus from cold-induced damage in cucumber (Cucumis sativus) plants. Recovery at both high light (HL) and low light (LL) after a cooling at 10/7 degrees C induced irreversible inhibition of CO2 assimilation, photoinhibition at photosystem I (PSI) and inhibition of enzyme activities of Calvin cycle and ascorbate (AsA)-reduced glutathione (GSH) cycle, followed by accumulation of H2O2 and malondialdehyde. However, cold-induced photoinhibition at PSII was fully recovered at LL but not at HL. Meanwhile, recovery at HL increased electron flux to O2-dependent alternative pathway [Ja(O2-dependent)]. Foliar application of 24-epibrassinolide (EBR) accelerated recovery from photoinhibition of PSII but not of PSI. EBR also significantly increased CO2 assimilation, activity of Calvin cycle enzymes and electron flux to carbon reduction [Je(PCR)], with a concomitant decrease in Ja(O2-dependent); meanwhile EBR increased the activity of enzymes in AsA-GSH cycle and cellular redox states. However, the positive effect of EBR on plant recovery was observed only at HL, but not LL. These results indicate that BR accelerates the recovery of photosynthetic apparatus at HL by activation of enzymes in Calvin cycle and increasing the antioxidant capacity, which in turn mitigate the photooxidative stress and the inhibition of plant growth during the recovery.