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.

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Keywords Arabidopsis, AtMKK1 knockout mutant, Formate dehydrogenase, Proteomic analysis, Salt tolerance
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Journal Plant Signaling and Behavior
Conroy, C. (Chad), Ching, J. (Jacqueline), Gao, Y. (Yan), Wang, X. (Xiaojing), Rampitsch, C. (Christof), & Xing, T. (2013). Knockout of AtMKK1 enhances salt tolerance and modifies metabolic activities in Arabidopsis. Plant Signaling and Behavior, 8(5). doi:10.4161/psb.24206