Reactive Carbonyl Species Function as Signal Mediators Downstream of H2O2 Production and Regulate [Ca2+]cyt Elevation in ABA Signal Pathway in Arabidopsis Guard Cells

We have demonstrated that reactive carbonyl species (RCS) function as an intermediate downstream of hydrogen peroxide (H2O2) production in abscisic acid (ABA) signaling for stomatal closure in guard cells using transgenic tobacco plants overexpressing alkenal reductase. We investigated the conversion of the RCS production into downstream signaling events in the guard cells. Both ABA and H2O2 induced production of the RCS, such as acrolein and 4-hydroxy-(E)-2-nonenal (HNE), in epidermal tissues of wild-type Arabidopsis thaliana plants. Application of the RCS scavengers, carnosine and pyridoxamine, did not affect the ABA-induced H2O2 production but inhibited the ABA- and H2O2-induced stomatal closure. Both acrolein and HNE induced stomatal closure in a plasma membrane NAD(P)H oxidase mutant atrbohD atrbohF as well as in the wild…