title: Arabidopsis MKK4 mediates osmotic-stress response via its regulation of MPK3 activity.
abstract: Plants have developed disparate regulatory pathways to adapt to environmental stresses. In this study, we identified MKK4 as an important mediator of plant response to osmotic stress. mkk4 mutants were more sensitive to high salt concentration than WT plants, exhibiting higher water-loss rates under dehydration conditions and additionally accumulating high levels of ROS. In contrast, MKK4-overexpressing transgenic plants showed tolerance to high salt as well as lower water-loss rates under dehydration conditions. In-gel kinase assays revealed that MKK4 regulates the activity of MPK3 upon NaCl exposure. Semi-quantitative RT-PCR analysis showed that expression of NCED3 and RD29A was lower and higher in mkk4 mutants and MKK4-overexpressing transgenic plants, respectively. Taken together, our results suggest that MKK4 is involved in the osmotic-stress response via its regulation of MPK3 activity.
authors.affiliation: Department of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Sun-Ho
authors.initials: SH
authors.lastname: Kim
authors.forename: Dong-Hyuk
authors.initials: DH
authors.lastname: Woo
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Woo Sik
authors.initials: WS
authors.lastname: Chung
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Moon
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009997:Osmotic Pressure; D010940:Plant Proteins / Q000235:genetics; D054712:Salinity; D013312:Stress, Physiological; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; C520629:RD29a protein, Arabidopsis; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase; C458516:AtMPK3 protein, Arabidopsis; C519871:MKK4 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases