期刊
PLANT JOURNAL
卷 103, 期 3, 页码 1140-1154出版社
WILEY
DOI: 10.1111/tpj.14791
关键词
chloroplast; glutathione redox potential; photosynthesis; glutathione reductase; redox-sensitive GFP; reactive oxygen species; non-photochemical quenching; Physcomitrella patens; moss
资金
- Deutsche Forschungsgemeinschaft (DFG) [ME1567/9-1/2, SCHW1719/7-1, HI 739/13-1, HI 739/13-2]
- Excellence Initiative of the German Federal and State Governments [EXC 294]
- 'Plant Mitochondria in New Light Initiative' (DFG) [PAK918, SCHW1719/5-1, MU4137/1-1]
- Deutsche Forschungsgemeinschaft (DFG) under Germany's Excellence Strategy - EXC 2048/1 [390686111]
Thiol-based redox-regulation is vital for coordinating chloroplast functions depending on illumination and has been throroughly investigated for thioredoxin-dependent processes. In parallel, glutathione reductase (GR) maintains a highly reduced glutathione pool, enabling glutathione-mediated redox buffering. Yet, how the redox cascades of the thioredoxin and glutathione redox machineries integrate metabolic regulation and detoxification of reactive oxygen species remains largely unresolved because null mutants of plastid/mitochondrial GR are embryo-lethal in Arabidopsis thaliana. To investigate whether maintaining a highly reducing stromal glutathione redox potential (E-GSH) via GR is necessary for functional photosynthesis and plant growth, we created knockout lines of the homologous enzyme in the model moss Physcomitrella patens. In these viable mutant lines, we found decreasing photosynthetic performance and plant growth with increasing light intensities, whereas ascorbate and zeaxanthin/antheraxanthin levels were elevated. By in vivo monitoring stromal E-GSH dynamics, we show that stromal E-GSH is highly reducing in wild-type and clearly responsive to light, whereas an absence of GR leads to a partial glutathione oxidation, which is not rescued by light. By metabolic labelling, we reveal changing protein abundances in the GR knockout plants, pinpointing the adjustment of chloroplast proteostasis and the induction of plastid protein repair and degradation machineries. Our results indicate that the plastid thioredoxin system is not a functional backup for the plastid glutathione redox systems, whereas GR plays a critical role in maintaining efficient photosynthesis.
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