温度上升提高了黄瓜叶片线粒体交替氧化酶呼吸途径对光破坏防御作用的贡献

Temperature Rise Enhances Photoprotection in Cucumber Leaves via Mitochondrial Alternative Oxidase (AOX) Pathway

本文以黄瓜为实验材料,研究了不同温度下植物叶片交替氧化酶呼吸途径(AOX途径)对光破坏防御贡献的差异及其机理。结果表明,低温不仅抑制了AOX途径的活性,还抑制了"Malate-OAA"穿梭,导致光合作用产生的过剩还原力NAD(P)H的消耗减少,低温下抑制AOX途径后没有加重叶片光抑制;而高温下AOX途径活性的上调有效消耗了通过"Malate-OAA"穿梭机制转运而来的过剩还原力,缓解了光合电子传递链的过度还原,并且AOX途径受抑后,叶片光抑制显著增加。上述结果表明AOX途径在低温下对光破坏防御的贡献受到明显限制,而在高温下AOX途径的上调增加了其对光破坏防御的贡献。

The diversity roles of mitochondrial alternative oxidase （AOX） pathway in photoprotection in cucumber leaves under low and high temperatures were studied, and the photoprotection mechanisms of the AOX pathway under different temperatures were also discussed. The results indicated that chilling not only inhibited AOX pathway activity but also inhibited the ＂Malate-OAA＂ shuttle, as a result the consuming of excess reducing equivalents via AOX pathway decreased, which limited the capability of photoprotection via AOX pathway under low temperature. While under high temperature, up-regulation of the activity of AOX pathway enhanced the consuming of the excess reducing equivalents from chloroplasts through the ＂Malate-OAA＂ shuttle, which alleviated the over-reduction of the photosynthetic electron transport chain. Above all, AOX pathway of cucumber leaves has a more important role in photoprotection under high temperature than under low temperature.