Abstract
Protein phosphorylation and dephosphorylation are most widely used regulatory mechanism in signal transduction. It has been implicated that MAP kinase cascades are involved in the regulation of plant disease resistance. MAP kinases are activated by upstream MAPK kinases. However, few negative regulators of plant MAP kinase have been reported. In the present study, we characterized protein phosphatases that inactivated StMPK1, a potato MAP kinase activated by various elicitors. StMPK1 was inactivated by crude extract from potato suspension cultured cells. The inactivation of StMPK1 was inhibited serine/threonine phosphatase inhibitors. Recently, alfalfa MP2C has been shown to be responsible for the dephosphrylation of activated MAPK. We isolated potato MP2C from potato cDNA library using homology-based PCR cloning. The potato MP2C dephosphorylated and inactivated StMPK1, suggesting the involvement of potato MP2C in resistant reactions.
