Abstract
Methyl jasmonate (MeJA) induces stomatal closure dependent on change of cytosolic Ca2+ concentration in guard cells. However, details of this molecular mechanism remain unclear. Calcium-dependent protein kinases (CDPKs) function as Ca2+ signal transducers in various plant physiological processes. It was suggested that Arabidopsis four CDPKs, CPK3, CPK6, CPK4, and CPK11 function as positive regulators in abscisic acid signaling in guard cells. Here, we examined roles of these CDPKs in MeJA signaling in guard cells using each CDPK knockout mutant. In CPK6 gene disruption mutants, MeJA-induced stomatal closure was impaired whereas in CPK3, CPK4, and CPK11 gene disruption mutants, MeJA-induced stomatal closure were not altered. We also evaluated roles of CPK6 in MeJA regulation of second messenger production and ion channel activity in guard cells. Our results provide genetic evidence that CPK6 functions as a positive regulator of MeJA signaling in Arabidopsis guard cells.
