title: Glutathione reductase 2 maintains the function of photosystem II in Arabidopsis under excess light.
abstract: Glutathione reductase plays a crucial role in the elimination of H(2)O(2) molecules via the ascorbate-glutathione cycle. In this study, we used transgenic Arabidopsis plants with decreased glutathione reductase 2 (GR2) levels to investigate whether this GR2 activity protects the photosynthetic machinery under excess light. The transgenic plants were highly sensitive to excess light and accumulated high levels of H(2)O(2). Photosystem II (PSII) activity was significantly decreased in transgenic plants. Flash-induced fluorescence relaxation and thermoluminescence measurements demonstrated inhibition of electron transfer between Q(A) and Q(B) and decreased redox potential of Q(B) in transgenic plants. Immunoblot and blue native gel analysis showed that the levels of PSII proteins and PSII complexes were decreased in transgenic plants. Analyses of the repair of photodamaged PSII and in vivo pulse labeling of thylakoid proteins showed that the repair of photodamaged PSII is inhibited due to the inhibition of the synthesis of the D1 protein de novo in transgenic plants. Taken together, our results suggest that under excess light conditions, GR2 plays an important role in maintaining both the function of the acceptor side of PSII and the repair of photodamaged PSII by preventing the accumulation of H(2)O(2). In addition, our results provide details of the role of H(2)O(2) in vivo accumulation in photoinhibition in plants.
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Shunhua
authors.initials: S
authors.lastname: Ding
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Jiang
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Qingtao
authors.initials: Q
authors.lastname: Lu
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Wen
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. Electronic address: lucm@ibcas.ac.cn.
authors.forename: Congming
authors.initials: C
authors.lastname: Lu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000235:genetics / Q000528:radiation effects; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005980:Glutathione Reductase / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D015151:Immunoblotting; D008027:Light; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D013816:Thermodynamics; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D006861:Hydrogen Peroxide; D005980:Glutathione Reductase; C000609479:glutathione reductase 2, Arabidopsis
keywords: Arabidopsis; Excess light; Glutathione reductase 2; Photoinhibition; Photosystem II