title: Knockout of AtMKK1 enhances salt tolerance and modifies metabolic activities in Arabidopsis.
abstract: Mitogen-activated protein kinase (MAPK) pathways represent a crucial regulatory mechanism in plant development. The ability to activate and inactivate MAPK pathways rapidly in response to changing conditions helps plants to adapt to a changing environment. AtMKK1 is a stress response kinase that is capable of activating the MAPK proteins AtMPK3, AtMPK4 and AtMPK6. To elucidate its mode of action further, several tests were undertaken to examine the response of AtMKK1 to salt stress using a knockout (KO) mutant of AtMKK1. We found that AtMKK1 mutant plants tolerated elevated levels of salt during both germination and adulthood. Proteomic analysis indicated that the level of the α subunit of mitochrondrial H(+)-ATPase, mitochrondial NADH dehydrogenase and mitochrondrial formate dehydrogenase was enhanced in AtMKK1 knockout mutants upon high salinity stress. The level of formate dehydrogenase was further confirmed by immunoblotting and enzyme assay. The possible involvement of these enzymes in salt tolerance is discussed.
authors.affiliation: Department of Biology and Institute of Biochemistry; Carleton University; Ottawa, ON Canada.
authors.forename: Chad
authors.initials: C
authors.lastname: Conroy
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Ching
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Wang
authors.forename: Christof
authors.initials: C
authors.lastname: Rampitsch
authors.forename: Tim
authors.initials: T
authors.lastname: Xing
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D005560:Formate Dehydrogenases / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055786:Gene Knockout Techniques; D018525:Germination / Q000187:drug effects / Q000235:genetics; D006720:Homozygote; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D009154:Mutation / Q000235:genetics; D040901:Proteomics; D054712:Salinity; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D012965:Sodium Chloride; D005560:Formate Dehydrogenases; D048369:MAP Kinase Kinase 1; C458515:MEK1 protein, Arabidopsis
keywords: Arabidopsis; AtMKK1 knockout mutant; formate dehydrogenase; proteomic analysis; salt tolerance