title: Mitogen-activated protein kinase kinase 5 (MKK5)-mediated signalling cascade regulates expression of iron superoxide dismutase gene in Arabidopsis under salinity stress.
abstract: Superoxide dismutases (SODs) are involved in plant adaptive responses to biotic and abiotic stresses but the upstream signalling process that modulates their expression is not clear. Expression of two iron SODs, FSD2 and FSD3, was significantly increased in Arabidopsis in response to NaCl treatment but blocked in transgenic MKK5-RNAi plant, mkk5. Using an assay system for transient expression in protoplasts, it was found that mitogen-activated protein kinase kinase 5 (MKK5) was also activated in response to salt stress. Overexpression of MKK5 in wild-type plants enhanced their tolerance to salt treatments, while mkk5 mutant exhibited hypersensitivity to salt stress in germination on salt-containing media. Moreover, another kinase, MPK6, was also involved in the MKK5-mediated iron superoxide dismutase (FSD) signalling pathway in salt stress. The kinase activity of MPK6 was totally turned off in mkk5, whereas the activity of MPK3 was only partially blocked. MKK5 interacted with the MEKK1 protein that was also involved in the salt-induced FSD signalling pathway. These data suggest that salt-induced FSD2 and FSD3 expressions are influenced by MEKK1 via MKK5-MPK6-coupled signalling. This MAP kinase cascade (MEKK1, MKK5, and MPK6) mediates the salt-induced expression of iron superoxide dismutases.
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.affiliation: Institute of Agro-Products Processing Science & Technology CAAS, Beijing, China.
authors.forename: Wei-hua
authors.initials: WH
authors.lastname: Chen
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing, China.
authors.forename: Wensuo
authors.initials: W
authors.lastname: Jia
authors.affiliation: School of Life Sciences, State Key Laboratory of Agrobiotechnology, and Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China jhzhang@cuhk.edu.hk.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D055049:Salt Tolerance; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D012965:Sodium Chloride; D013482:Superoxide Dismutase; C519872:MKK5 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: Arabidopsis; FSD; iron superoxide dismutase; mitogen-activated protein kinase 6; mitogen-activated protein kinase kinase 5; salt stress.