Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
Plant Physiol Biochem. 2012 Nov;60:141-9. doi: 10.1016/j.plaphy.2012.07.010. Epub 2012 Aug 2.
Cold acclimation increases plant tolerance to a more-severe chilling and in this process an accumulation of H(2)O(2) in plants is often observed. To examine the role of H(2)O(2) in cold acclimation in plants, the accumulation of H(2)O(2), antioxidant metabolism, the glutathione redox state, gas exchange and chlorophyll fluorescence were analyzed after cold acclimation at 12/10 °C and during the subsequent chilling at 7/4 °C in tomato (Solanum lycopersicum) plants. Cold acclimation modestly elevated the levels of H(2)O(2), the gene expression of respiratory burst oxidase homolog 1 (Rboh1) and NADPH oxidase activity, leading to the up-regulation of the expression and activity of antioxidant enzymes. In non-acclimated plants chilling caused a continuous rise in the H(2)O(2) content, an increase in the malondialdehyde (MDA) content and in the oxidized redox state of glutathione, followed by reductions in the CO(2) assimilation rate and the maximum quantum yield of photosystem II (F(v)/F(m)). However, in cold-acclimated plants chilling-induced photoinhibition, membrane peroxidation and reductions in the CO(2) assimilation rate were significantly alleviated. Furthermore, a treatment with an NADPH oxidase inhibitor or H(2)O(2) scavenger before the plants subjected to the cold acclimation abolished the cold acclimation-induced beneficial effects on photosynthesis and antioxidant metabolism, leading to a loss of the cold acclimation-induced tolerance against chilling. These results strongly suggest that the H(2)O(2) generated by NADPH oxidase in the apoplast of plant cells plays a crucial role in cold acclimation-induced chilling tolerance.
冷驯化会增加植物对更严重冷害的耐受性，在此过程中，植物中通常会观察到 H₂O₂的积累。为了研究 H₂O₂在植物冷驯化中的作用，在 12/10°C 下进行冷驯化后，以及随后在 7/4°C 下进行冷胁迫时，分析了番茄（Solanum lycopersicum）植株中 H₂O₂的积累、抗氧化代谢、谷胱甘肽氧化还原状态、气体交换和叶绿素荧光。冷驯化适度提高了 H₂O₂水平、呼吸爆发氧化酶同源物 1（Rboh1）的基因表达和 NADPH 氧化酶活性，导致抗氧化酶的表达和活性上调。在未驯化的植物中，冷胁迫导致 H₂O₂含量持续升高，丙二醛（MDA）含量增加，谷胱甘肽的氧化还原状态增加，随后 CO₂同化率和光系统 II 的最大量子产量（Fv/Fm）降低。然而，在冷驯化的植物中，冷胁迫诱导的光抑制、膜过氧化和 CO₂同化率降低得到显著缓解。此外，在植物进行冷驯化之前，用 NADPH 氧化酶抑制剂或 H₂O₂清除剂处理会消除冷驯化对光合作用和抗氧化代谢的有益影响，导致冷驯化诱导的对冷胁迫的耐受性丧失。这些结果强烈表明，植物细胞质外体中 NADPH 氧化酶产生的 H₂O₂在冷驯化诱导的耐冷性中起着至关重要的作用。
