title: Cellular glutathione redox homeostasis plays an important role in the brassinosteroid-induced increase in CO2 assimilation in Cucumis sativus.
abstract: Brassinosteroids (BRs) play a vital role in plant growth, stress tolerance and productivity. Here, the involvement of BRs in the regulation of CO(2) assimilation and cellular redox homeostasis was studied. The effects of BRs on CO(2) assimilation were studied in cucumber (Cucumis sativus) through the analysis of the accumulation of H(2)O(2) and glutathione and photosynthesis-related enzyme activities using histochemical and cytochemical detection or a spectrophotometric assay, and Rubisco activase (RCA) using western blot analysis and immunogold labeling. Exogenous BR increased apoplastic H(2)O(2) accumulation, the ratio of reduced to oxidized glutathione (GSH:GSSG) and CO(2) assimilation, whereas a BR biosynthetic inhibitor had the opposite effects. BR-induced CO(2) assimilation was decreased by a H(2)O(2) scavenger or inhibition of H(2)O(2) generation, GSH biosynthesis and the NADPH-generating pentose phosphate pathway. BR-, H(2)O(2) - or GSH-induced CO(2) assimilation was associated with increased activity of enzymes in the Benson-Calvin cycle. Immunogold labeling and western blotting showed that BR increased the content of RCA and this effect was blocked by inhibitors of redox homeostasis. These results strongly suggest that BR-induced photosynthesis involves an H(2)O(2) -mediated increase in the GSH:GSSG ratio, which may positively regulate the synthesis and activation of redox-sensitive enzymes in carbon fixation.
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Jiang
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Cheng
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Xia
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Mao
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.|Department of Botany & Plant Pathology, Purdue University, West Lafayette, IN 47907-2054, USA.
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China.|Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Ministry of Agriculture of China, Zijingang Road 866, Hangzhou 310058, China.
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
mesh_terms: D060406:Brassinosteroids / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000378:metabolism*; D002778:Cholestanones / Q000494:pharmacology*; D018553:Cucumis sativus / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis; D010937:Plant Growth Regulators / Q000494:pharmacology*; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
chemical_list: D060406:Brassinosteroids; D002778:Cholestanones; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; D002245:Carbon Dioxide; C070163:homobrassinolide; D006861:Hydrogen Peroxide; D005978:Glutathione; C023623:brassinolide