Mitochondrial Alternative Pathway-Associated Photoprotection of Photosystem II is Related to the Photorespiratory Pathway

Plant & Cell Physiology
Chihiro K WatanabeKo Noguchi

Abstract

Respiratory electron transport has two ubiquinol-oxidizing pathways, the cytochrome pathway (CP) and the alternative pathway (AP). The AP, which is catalyzed by the alternative oxidase (AOX), is energetically wasteful but may alleviate PSII photoinhibition under light conditions excessive for photosynthesis. However, its mechanism remains unknown. We used Arabidopsis aox1a mutants lacking AOX activity and studied the mutation's effects on photoinhibition by measuring the decrease in the maximum quantum yield of PSII (Fv/Fm) after high light exposure. Since the CP compensates for the lack of AOX, we monitored the extent of photoinhibition under conditions where CP activity is partially inhibited by antimycin A. When leaves were exposed to high light at 350 µmol m(-2) s(-1), the decline in Fv/Fm was significantly faster in the aox1a mutants than in the wild type. However, under conditions where photorespiration was suppressed by high CO2 or low O2 levels, the decline in Fv/Fm was suppressed in the aox1a mutants, but not in the wild type, making the difference between the wild type and mutants small. Our results demonstrate that the lack of the AP causes an acceleration of PSII photoinhibition in relation to the photorespiratory p...Continue Reading

References

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Citations

Jul 20, 2020·The Plant Journal : for Cell and Molecular Biology·Yu-Ting LiZi-Shan Zhang
Dec 3, 2016·Plant & Cell Physiology·Jun'ichi ManoChikahiro Miyake
Sep 22, 2018·Materials·Julietta MoustakaMichael Moustakas
May 5, 2020·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·Aleksandra Adamowicz-SkrzypkowskaHanna Janska
Nov 23, 2021·Frontiers in Plant Science·Nestor Fernandez Del-SazJaume Flexas

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