Hydrogen sulfide generated by hydrogen peroxide mediates darkness-induced stomatal closure in arabidopsis thaliana

Hydrogen sulfide (H/sub 2/S) plays an important role in the regulation of stomatal movement in plants. Here we present the relationships and functions of H/sub 2/S and hydrogen peroxide (H/sub 2/O/sub 2/) in stomatal movement by darkness in Arabidopsis thaliana. H/sub 2/S synthesis inhibitors and scavengers inhibited darkness-induced stomatal closure, H/sub 2/S generation and L-/Dcysteine desulfhydrase (L-/D-CDes) activity increase in wild-type leaves. Darkness induced stomatal closure in wild-type plants, but failed in L-/D-CDes deletion mutants Atl-cdes and Atd-cdes. Additionally, both L-/D-CDes activity and H/sub 2/S content were significantly decreased after applying H/sub 2/O/sub 2/ synthesis inhibitors and scavengers, but there was almost no effects on H/sub 2/O/sub 2/ levels in the presence of H/sub 2/S synthesis inhibitors and scavengers in wild-type leaves in darkness. Moreover, darkness couldn't increase H/sub 2/S content and L-/D-CDes activity of mutant lines of NADPH oxidase gene AtrbohF and AtrbohD/F mutants leaves, but increased H/sub 2/O/sub 2/ levels in Atl-cdes and Atd-cdes guard cells. Taken together, we conclude that both H/sub 2/S and H/sub 2/O/sub 2/ are involved in darkness-induced stomatal closure, and H/sub 2/S functioned downstream of H/sub 2/O/sub 2/ in A. thaliana. Darkness induced H/sub 2/O/sub 2/ synthesis via promoting the activity of NADPH oxidase, and further led to the production of L-/D-CDes-derived H/sub 2/S and stomatal closure in A. thaliana. NADPH oxidase gene AtrbohF participated in the process. (author)