Physiological impact of mitochondrial alternative oxidase on photosynthesis and growth in Arabidopsis thaliana

• Published in: Plant, cell and environment cell and environment, 2011-11, Vol.34 (11), p.1890-1899
• Main Authors: YOSHIDA, KEISUKE, WATANABE, CHIHIRO K., TERASHIMA, ICHIRO, NOGUCHI, KO
• Format: Article
• Language: English
• Subjects: Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis - radiation effects; Arabidopsis thaliana; Biological and medical sciences; Chlorophyll - metabolism; cyclic electron transport around photosystem I; Fluorescence; Fundamental and applied biological sciences. Psychology; Growth; growth conditions; Light; Mitochondria - enzymology; Mitochondria - radiation effects; Mitochondrial Proteins - metabolism; Mutants; Mutation - genetics; organellar crosstalk; Oxidoreductases - metabolism; Phenotype; Photosynthesis; Photosynthesis - physiology; Photosynthesis - radiation effects; Photosystem I Protein Complex - metabolism; Photosystem II Protein Complex - metabolism; Physiology; plant growth; Plant Proteins - metabolism; proton gradient regulation 5; respiratory chain
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2011.02384.x

ABSTRACT 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. 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 AOX deficiency on a number of photosynthetic parameters and growth phenotypes under several light conditions in Arabidopsis. Our results indicate that AOX participates in regulating photosynthetic electron transport and is needed for plant development under conditions where the photosynthetic electron transport is severely restricted.