The MKK2 Pathway Mediates Cold and Salt Stress Signaling in Arabidopsis

• DOI: 10.1016/j.molcel.2004.06.023
• Publication Date: 2004-07-02T18:52:12Z
• Authors: Markus Teige; Elisabeth Scheikl; Thomas Eulgem; Róbert Dóczi; Kazuya Ichimura; Kazuo Shinozaki; Jeffery L. Dangl; Heribert Hirt
• Keywords: Mitogen-Activated Protein Kinase Kinases; Saline Solution, Hypertonic; 0301 basic medicine; 0303 health sciences; Arabidopsis Proteins; MAP Kinase Signaling System; Arabidopsis; 1060 Biologie; Cell Biology; MAP Kinase Kinase Kinases; Up-Regulation; Cold Temperature; Enzyme Activation; 03 medical and health sciences; Phenotype; Gene Expression Regulation, Plant; Yeasts; Mutation; 1060 Biology; Mitogen-Activated Protein Kinases; Molecular Biology

AbstractThe Arabidopsis mitogen-activated protein kinase (MAPK) kinase 2 (MKK2) and the downstream MAPKs MPK4 and MPK6 were isolated by functional complementation of osmosensitive yeast mutants. In Arabidopsis protoplasts, MKK2 was specifically activated by cold and salt stress and by the stress-induced MAPK kinase kinase MEKK1. Yeast two-hybrid, in vitro, and in vivo protein kinase assays revealed that MKK2 directly targets MPK4 and MPK6. Accordingly, plants overexpressing MKK2 exhibited constitutive MPK4 and MPK6 activity, constitutively upregulated expression of stress-induced marker genes, and increased freezing and salt tolerance. In contrast, mkk2 null plants were impaired in MPK4 and MPK6 activation and were hypersensitive to salt and cold stress. Full genome transcriptome analysis of MKK2-overexpressing plants demonstrated altered expression of 152 genes involved in transcriptional regulation, signal transduction, cellular defense, and stress metabolism. These data identify a MAP kinase signaling cascade mediating cold and salt stress tolerance in plants.