title: Calcium contributes to photoprotection and repair of photosystem II in peanut leaves during heat and high irradiance.
abstract: In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat (40°C) and high irradiance (HI) (1,200 µmol/m(2) per s) stress. Compared with control seedlings (cultivated in 0 mmol/L Ca(NO3 )2 medium), the maximal photochemical efficiency of photosystem II (PSII) in Ca(2+) -treated plants showed a slight decrease after 5 h stress, accompanied by lower degree of PSII closure (1-qP), higher non-photochemical quenching, and lower level of membrane damage. Ca(2+) inhibitors were used to analyze the varieties of antioxidant enzymes activity and PSII proteins. These results indicated that Ca(2+) could protect the subunits of PSII reaction centers from photoinhibition by reducing the generation of reactive oxygen species. In the presence of both ethyleneglycol-bis(2-aminoethylether)-tetraacetic acid and ascorbic acid (AsA), the net degradation of the damaged D1 protein was faster than that only treated with AsA. Our previous study showed that either the transcriptional or the translational level of calmodulin was obviously higher in Ca(2+) -treated plants. These results suggested that, under heat and HI stress, the Ca(2+) signal transduction pathway can alleviate the photoinhibition through regulating the protein repair process besides an enhanced capacity for scavenging reactive oxygen species.
authors.affiliation: Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan, 250100, China; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan, 250100, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Yang
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Meng
authors.forename: Xin-Guo
authors.initials: XG
authors.lastname: Li
authors.forename: Shu-Bo
authors.initials: SB
authors.lastname: Wan
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D010367:Arachis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D010940:Plant Proteins / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000378:metabolism; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects
chemical_list: D000975:Antioxidants; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D002118:Calcium
keywords: Calcium; D1 protein; heat and high irradiance stress; peanut; photosystem II