Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Plant Cell Environ. 2011 Nov;34(11):1890-9. doi: 10.1111/j.1365-3040.2011.02384.x. Epub 2011 Jul 21.
The mitochondrial alternative oxidase (AOX) has been suggested to have a beneficial role in illuminated leaves, but its function has not yet been fully elucidated. In this study, we investigated the effects of a knockout of the AOX1a gene on photosynthesis and growth under several light conditions in Arabidopsis thaliana. The AOX-deficient aox1a mutant showed a lowered operating efficiency of photosystem II and an enhanced activity of cyclic electron transport around photosystem I (CET-PSI) at high irradiance. To further address the physiological association of AOX with CET-PSI, we crossed aox1a with the pgr5 mutant, which is impaired in CET-PSI activity. In the pgr5 mutant background, AOX deficiency did not affect the apparent photosynthetic efficiency, indicating that the direct contribution of AOX to photosynthesis is not so large compared with CET-PSI. Nevertheless, the growth of the aox1a pgr5 double mutant was significantly impaired depending on the light intensity under growth conditions. The possibility of a synergistic function of AOX with CET-PSI in supporting plant growth is discussed.
线粒体替代氧化酶（AOX）被认为在受光叶片中具有有益作用，但它的功能尚未完全阐明。在这项研究中，我们研究了敲除拟南芥中的 AOX1a 基因对光合作用和几种光照条件下生长的影响。在高光强下，AOX 缺失的 aox1a 突变体表现出较低的光系统 II 运行效率和增强的光系统 I 周围环式电子传递（CET-PSI）活性。为了进一步研究 AOX 与 CET-PSI 的生理关联，我们将 aox1a 与 pgr5 突变体杂交，该突变体在 CET-PSI 活性中受损。在 pgr5 突变体背景下，AOX 缺失并不影响表观光合作用效率，表明与 CET-PSI 相比，AOX 对光合作用的直接贡献并不大。然而，在生长条件下，根据光照强度，aox1a pgr5 双突变体的生长受到显著损害。讨论了 AOX 与 CET-PSI 协同支持植物生长的可能性。
