title: MKK5 regulates high light-induced gene expression of Cu/Zn superoxide dismutase 1 and 2 in Arabidopsis.
abstract: Superoxide dismutases (SODs) convert the superoxide radical to hydrogen peroxide and molecular oxygen, and play crucial roles in plant tolerance to oxidative stress. Expression of many genes encoding SODs is promoted in response to environmental stresses, but the exact mechanism of such promotion is largely unknown. Here, we report that MKK5, a mitogen-activated protein kinase kinase, mediated the high light-induced expression of genes of two copper/zinc SODs, CSD1 and CSD2, and was involved in the oxidative adaptation to high light stress. In response to high light, wild-type Arabidopsis plants showed much enhanced expression of CSD1 and CSD2 and higher enzyme activity of MKK5. In the MKK5-RNAi (RNA interference) lines, however, the induction of CSD1 and CSD2 as well as the activation of MKK5 activity were completely arrested. In contrast, overexpression of MKK5 promoted the expression of CSD1 and CSD2. MKK5-RNAi gene silencing and CSD1/2-RNAi suppression plants became much more sensitive to high light stress than wild-type plants, and the double mutant mkk5 csd1 exhibited hypersensitivity to the stress. Plants overexpressing MKK5 showed enhanced tolerance to high light stress. Our results demonstrate that MKK5 mediated a signal of the high light-induced expression of the genes CSD1 and CSD2. Manipulating MKK5 and thereby up-regulating the levels of CSD1 and CSD2 transcripts can improve plant tolerance to high light stress.
authors.affiliation: Beijing Key Laboratory for Agricultural Application and New Technique and College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xing
authors.forename: Qingqin
authors.initials: Q
authors.lastname: Cao
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Wensuo
authors.initials: W
authors.lastname: Jia
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D015153:Blotting, Western; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008027:Light; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D007527:Isoenzymes; D013482:Superoxide Dismutase; C586060:CSD1 protein, Arabidopsis; C586061:CSD2 protein, Arabidopsis; C519872:MKK5 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: Arabidopsis; Cu/Zn SOD; High light stress; MAPK kinase