title: The reduced state of the plastoquinone pool is required for chloroplast-mediated stomatal closure in response to calcium stimulation.
abstract: Besides their participation in photosynthesis, leaf chloroplasts function in plant responses to stimuli, yet how they direct stimulus-induced stomatal movement remains elusive. Here, we showed that over-reduction of the plastoquinone (PQ) pool by dibromothymoquinone (DBMIB) was closely associated with stomatal closure in plants which required chloroplastic H2O2 generation in the mesophyll. External application of H2 O2 reduced the PQ pool, whereas the cell-permeable reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) reversed the DBMIB-induced over-reduction of the PQ pool and stomatal closure. Mesophyll chloroplasts are key players of extracellular Ca(2+) (Ca(2+)o)-induced stomatal closure, but when treated with either 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) or NAC they failed to facilitate Ca(2+)o-induced stomatal closure due to the inhibition of chloroplastic H2 O2 synthesis in mesophyll. Similarly, the Arabidopsis electron transfer chain-related mutants npq4-1, stn7 and cas-1 exhibited diverse responses to Ca(2+)o or DBMIB. Transcriptome analysis also demonstrated that the PQ pool signaling pathway shared common responsive genes with the H2 O2 signaling pathway. These results implicated a mechanism for chloroplast-mediated stomatal closure involving the generation of mesophyll chloroplastic H2O2 based on the reduced state of the PQ pool, which is calcium-sensing receptor (CAS) and LHCII phosphorylation dependent.
authors.affiliation: Fujian Key Laboratory of Subtropical Plant Physiology and Biochemistry, Fujian Institute of Subtropical Botany, Xiamen, Fujian, 361006, China.
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Wang
authors.affiliation: Fujian Key Laboratory of Subtropical Plant Physiology and Biochemistry, Fujian Institute of Subtropical Botany, Xiamen, Fujian, 361006, China.
authors.forename: En-Ming
authors.initials: EM
authors.lastname: He
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Chen
authors.affiliation: Fujian Key Laboratory of Subtropical Plant Physiology and Biochemistry, Fujian Institute of Subtropical Botany, Xiamen, Fujian, 361006, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, 361005, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Chen
authors.affiliation: Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, 361005, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, 361005, China.
authors.forename: Hai-Lei
authors.initials: HL
authors.lastname: Zheng
mesh_terms: D002736:Chloroplasts / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D054046:Plant Stomata / Q000378:metabolism*; D010944:Plants / Q000145:classification / Q000378:metabolism*; D010971:Plastoquinone / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D010971:Plastoquinone; D010100:Oxygen
keywords: Arabidopsis thaliana; calcium-sensing receptor; chlorophyll fluorescence; chloroplasts; hydrogen peroxide; plastoquinone pool; stomatal closure