G Protein and H2O2 were found to be involved in the guard cell signal transduction, and they could induce stomatal closure. But the molecular mechanisms about how they induced stomatal closure and what were the relationship between them has not been resolved. Here, by using Arabidopsis heterotrimeric G protein alpha subunit - null mutants gpa1-1 and gpa1-2, overexpression lines wGa and cGa, and atrbohD/F double mutant, which corresponding to the mutation of two guard cell special-expressed NADPH oxidase gen...