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The reduced state of the plastoquinone pool is required for chloroplast‐mediated stomatal closure in response to calcium stimulation
Author(s) -
Wang WenHua,
He EnMing,
Chen Juan,
Guo Ying,
Chen Juan,
Liu Xiang,
Zheng HaiLei
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13154
Subject(s) - plastoquinone , chloroplast , dcmu , arabidopsis , photosynthesis , biology , microbiology and biotechnology , biophysics , botany , chemistry , biochemistry , mutant , thylakoid , gene
Summary 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 H 2 O 2 generation in the mesophyll. External application of H 2 O 2 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 H 2 O 2 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 H 2 O 2 signaling pathway. These results implicated a mechanism for chloroplast‐mediated stomatal closure involving the generation of mesophyll chloroplastic H 2 O 2 based on the reduced state of the PQ pool, which is calcium‐sensing receptor ( CAS ) and LHCII phosphorylation dependent.