Abstract
Stomata open and close under several environmental conditions. Among them, ABA is known to close stomatal pores in response to drought stress. Since ABA signaling is inhibited by ethylene during seed germination, we investigate the cross-talk between ABA and ethylene in stomatal closure of Arabidopsis thaliana epidermal peels. Preopened stomata closed almost completely within 5 minutes in response to ABA but ethylene gas treatment suppressed the ABA-induced stomatal closure. Time course observation showed that under ethylene treatment, the rate of stomatal closure was not so affected but the stomatal closure stopped halfway. In the other hand, when we examined a change of fresh weight under drought stress in planta, plants exposed to ethylene gas in advance showed elevated amount of water loss compared to those of control plants. Therefore, ethylene may act as a negative regulator in the ABA signaling pathways to suppress the stomatal closure.
