Impact of mitochondrial alternative oxidase expression on the response of Nicotiana tabacum to cold temperature.
Impact of mitochondrial alternative oxidase expression on the response of Nicotiana tabacum to cold temperature.
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DOI：
10.1111/j.1399-3054.2011.01471.x
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发表时间：
2011-08
影响因子：
6.4
通讯作者：
Jia Wang;Nirusan Rajakulendran;S. Amirsadeghi;G. C. Vanlerberghe
中科院分区：
文献类型：
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作者：
Jia Wang;Nirusan Rajakulendran;S. Amirsadeghi;G. C. Vanlerberghe
植物线粒体电子传递链(ETC)包括一种非能量守恒的替代氧化酶(AOX)，被认为可以抑制ETC产生的ROS和/或通过将其与ATP代谢解偶联来促进碳代谢。在28℃/22℃(光/暗)条件下生长的野生型烟草在12℃/5℃条件下，在24 h内表现出大量的Aox1a mRNA和AOX蛋白的诱导，并导致单糖大量积累，编码重要的ROS清除酶基因的转录水平增加，脂质过氧化程度适度增加。与WT相比，AOX水平降低的转基因植株表现出较少的冷诱导糖积累，而AOX水平升高的转基因植株表现出更强的糖积累。这与AOX燃烧过量碳水化合物的假设不一致，而是表明AOX至少在冷应激期间帮助糖积累的作用。在28℃/22℃条件下，与WT相比，AOX被抑制的植株的脂质过氧化水平升高，而AOX被增强的植株的脂质过氧化水平降低。这与AOX抑制ROS生成和氧化损伤的假设是一致的。然而，AOX水平和脂质过氧化之间的这种负相关关系在转变为低温时并不成立。在这种胁迫条件下，与WT相比，AOX抑制较强的植物表现出更强的ROS清除酶的诱导和膜脂过氧化作用的降低。这些数据表明，在应激条件下，AOX的缺乏增强了线粒体的应激信号通路，从而能够增加细胞清除ROS的能力。
The plant mitochondrial electron transport chain (ETC) includes a non-energy conserving alternative oxidase (AOX) thought to dampen reactive oxygen species (ROS) generation by the ETC and/or facilitate carbon metabolism by uncoupling it from ATP turnover. When wild-type (WT) Nicotiana tabacum grown at 28°C/22°C (light/dark) were transferred to 12°C/5°C, they showed a large induction of leaf Aox1a mRNA and AOX protein within 24 h. Transfer to cold also resulted in a large accumulation of monosaccharides, an increase in transcript level of genes encoding important ROS-scavenging enzymes and a moderate increase in lipid peroxidation. Transgenic plants with suppressed AOX level showed less cold-induced sugar accumulation than WT while transgenic plants with enhanced AOX levels showed enhanced sugar accumulation. This is inconsistent with the hypothesis that AOX acts to burn excess carbohydrate, but rather suggests a role for AOX to aid sugar accumulation, at least during cold stress. At 28°C/22°C, plants with suppressed AOX had elevated levels of lipid peroxidation compared with WT, while plants with enhanced AOX had reduced lipid peroxidation. This is consistent with the hypothesis that AOX dampens ROS generation and oxidative damage. However, this inverse relationship between AOX level and lipid peroxidation did not hold upon shift to cold. Under this stress condition, plants with strong suppression of AOX show enhanced induction of ROS-scavenging enzymes compared with WT and decline in lipid peroxidation. These data suggest that, under stress conditions, the lack of AOX enhances a mitochondrial stress-signaling pathway able to increase the ROS-scavenging capacity of the cell.