MPK6 Kinase Regulates Plasma Membrane H-ATPase Activity in Cold Acclimation.

Cold and freezing stresses severely affect plant growth, development, and survival rate. Some plant species have evolved a process known as cold acclimation, in which plants exposed to temperatures above 0 °C trigger biochemical and physiological changes to survive freezing. During this response, several signaling events are mediated by transducers, such as mitogen activated protein kinase (MAPK) cascades. Plasma membrane H-ATPase is a key enzyme for the plant cell life under regular and stress conditions. Using wild type and and knock out mutants in , we explored the transcriptional, translational, and 14-3-3 protein regulation of the plasma membrane H-ATPase activity under the acclimation process. The kinetic analysis revealed a differential profiling of the H-ATPase activity depending on the presence or absence of MPK3 or MPK6 under non-acclimated or acclimated conditions. Negative regulation of the plasma membrane H-ATPase activity was found to be exerted by MPK3 in non-acclimated conditions and by MPK6 in acclimated conditions, describing a novel form of regulation of this master ATPase. The MPK6 regulation involved changes in plasma membrane fluidity. Moreover, our results indicated that MPK6 is a critical regulator in the process of cold acclimation that leads to freezing tolerance and further survival.