Reactive oxigen species regulation in ABA signaling in Arabidopsis guard cells

Abstract

Only a few signal transduction components have been identified from recessive ABA insensitive disruption mutants, most likely due to redundancy in genes encoding ABA signaling components. To dissect redundant signal transduction genes, we have developed an alternative "single cell-type genomics" approach.
Reactive oxygen species (ROS) have been proposed to function as second messengers in ABA signaling in guard cells. However, the molecular mechanisms mediating ROS production remain unknown. Double knockout mutation of the Arabidopsis guard cell-expressed NADPH oxidases impairs ABA-induced stomatal closing, ROS production and cytosolic Ca²⁺ increases in guard cells and ABA-activation of plasma membrane Ca²⁺ channels. ABA promotes superoxide production in wildtype guard cell protoplasts, but not in the mutant. These data suggest that the ROS produced by NADPH oxidases function as second messengers in guard cell ABA signal transduction. Furthermore new data on analyzing roles of ROS generation and scavenging in guard cell will be presented.