Enhanced sensitivity and characterization of photosystem II in transgenic tobacco plants with decreased chloroplast glutathione reductase under chilling stress.
Chloroplast glutathione reductase (GR) plays an important role in protecting photosynthesis against oxidative stress. We used transgenic tobacco (Nicotiana tabacum) plants with severely decreased GR activities by using a gene encoding tobacco chloroplast GR for the RNAi construct to investigate the possible mechanisms of chloroplast GR in protecting photosynthesis against chilling stress. Transgenic plants were highly sensitive to chilling stress and accumulated high levels of H₂O₂ in chloroplasts. Spectroscopic analysis and electron transport measurements show that PSII activity was significantly reduced in transgenic plants. Flash-induced fluorescence relaxation and thermoluminescence measurements demonstrate that there was a slow electron transfer between Q(A) and Q(B) and decreased redox potential of Q(B) in transgenic plants, whereas the donor side function of PSII was not affected. Immunoblot and blue native gel analyses illustrate that PSII protein accumulation was decreased greatly in transgenic plants. Our results suggest that chloroplast GR plays an important role in protecting PSII function by maintaining the electron transport in PSII acceptor side and stabilizing PSII complexes under chilling stress. Our results also suggest that the recycling of ascorbate from dehydroascorbate in the ascorbate-glutathione cycle in the chloroplast plays an essential role in protecting PSII against chilling stress.
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 10093, China.
Shunhua
S
Ding
Ming
M
Lei
Qingtao
Q
Lu
Aihong
A
Zhang
Yan
Y
Yin
Xiaogang
X
Wen
Lixin
L
Zhang
Congming
C
Lu
D001205:Ascorbic Acid / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D003080:Cold Temperature; D004579:Electron Transport; D005980:Glutathione Reductase / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D045332:Photosystem II Protein Complex / Q000032:analysis / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D005980:Glutathione Reductase; D001205:Ascorbic Acid