Roles of a putative mechanosensitive plasma membrane Ca2+-permeable channel OsMCA1 in generation of reactive oxygen species and hypo-osmotic signaling in rice.

Mechanosensing and its downstream responses are speculated to involve sensory complexes containing Ca(2+)-permeable mechanosensitive channels. On recognizing hypo-osmotic stress, plant cells initiate activation of a widespread signal transduction network involving second messengers such as Ca(2+) to trigger inducible defense responses including the induction of transcriptional factors. However, most of the components involved in these signaling networks still remain to be identified. Recently we identified and investigated OsMCA1, the sole homolog of the MCA family putative Ca(2+)-permeable mechanosensitive channels in rice. Functional characterization of the OsMCA1-suppressed cells as well as the overexpressing cells indicated that OsMCA1 is involved in the regulation of plasma membrane Ca(2+) influx and NADPH oxidase-mediated generation of reactive oxygen species (ROS) induced by hypo-osmotic stress. Here we will discuss possible molecular mechanisms and physiological functions of the MCA protein in hypo-osmotic signaling.