Arabidopsis MAPK signaling pathways and their cross talks in abiotic stress response

Plants, being sessile in nature have developed refined mechanisms to rapidly sense changing environment and protect themselves from environmental stresses. Mitogen activated protein kinase (MAPK) cascade are the common mechanisms for translating the extreneous environmental signal to molecular and cellular responses. MAPK signaling component involves reversible phosphorylation at specific residue, where upstream activator MAPK kinase kinases (MAPKKKs) activate MAPK kinases (MAPKKs). MAPKK further activate MAPKs, which in turn target various effector proteins or transcription factor and thus causes various cellular and stress response. In plants, MAPK cascades are associated with the signaling of numerous environmental cues and plant growth and development. MAPK pathways are widely studied and functionally characterized in Arabidopsis thaliana, a well-established model plant for molecular and genetic studies. Arabidopsis genome has 20 MAPKs, 10 MAPKKs and 80 MAPKKKs, most of which are still functionally uncharacterized. Much of the studies have been focused on lower tier of MAPK cascade and complete pathways under abiotic stresses are largely unknown. The present review highlights Arabidopsis MAPK pathway activation and responses involved in various abiotic stresses viz. salt, drought, heat, cold, heavy metal, wounding and oxidative stress. The cross talks of Arabidopsis MAPK signaling pathway in abiotic stress responses are also discussed.