S-nitrosylation coordinates stomatal development and functions.

Nitric oxide (NO) regulates stomatal initiation, proliferation, and function but the precise mechanisms of action remain poorly documented. In this issue of Developmental Cell, Wang et al. show that NO-mediated S-nitrosylation inhibits the phosphorylation activity of mitogen-activated protein kinase 6, allowing stabilization of the SPEECHLESS transcription factor and promoting stomatal development.