Alteration of stimulus-specific guard cell calcium oscillations and stomatal closing in Arabidopsis det3 mutant

Cytosolic calcium oscillations control signaling in animal cells, whereas i n plants their importance remains Largely unknown. In wild-type Arabidopsis guard cells abscisic acid, oxidative stress, cold, and external calcium el icited cytosolic calcium oscillations of differing amplitudes and frequenci es and induced stomatal closure. In guard cells of the V-ATPase mutant det3 , external calcium and oxidative stress elicited prolonged calcium increase s, which did not oscillate, and stomatal closure was abolished. Conversely, cold and abscisic acid elicited calcium oscillations in det3, and stomatal closure occurred normally. Moreover, in det3 guard cells, experimentally i mposing external calcium-induced oscillations rescued stomatal closure. The se data provide genetic evidence that stimulus-specific calcium oscillation s are necessary for stomatal closure.