Hydrogen peroxide is required for light-induced stomatal opening across different plant species

Stomatal movement is vital for plants to exchange gases and adaption to terrestrial habitats, which is regulated by environmental and phytohormonal signals. Here, we demonstrate that hydrogen peroxide (H 2 O 2 ) is required for light-induced stomatal opening. H 2 O 2 accumulates specifically in guard cells even when plants are under unstressed conditions. Reducing H 2 O 2 content through chemical treatments or genetic manipulations results in impaired stomatal opening in response to light. This phenomenon is observed across different plant species, including lycopodium, fern, and monocotyledonous wheat. Additionally, we show that H 2 O 2 induces the nuclear localization of KIN10 protein, the catalytic subunit of plant energy sensor SnRK1. The nuclear-localized KIN10 interacts with and phosphorylates the bZIP transcription factor bZIP30, leading to the formation of a heterodimer between bZIP30 and BRASSINAZOLE-RESISTANT1 (BZR1), the master regulator of brassinosteroid signaling. This heterodimer complex activates the expression of amylase , which enables guard cell starch degradation and promotes stomatal opening. Overall, these findings suggest that H 2 O 2 plays a critical role in light-induced stomatal opening across different plant species. Specific accumulated H 2 O 2 in guard cells under unstressed conditions widely existed among plant species and is required for stomatal opening. H 2 O 2 promotes KIN10, the energy regulator for plant cells, localizing in the nucleus of guard cells to phosphorylate bZIP30 and enhance the heterodimer of bZIP30 and BZR1, thereby facilitating guard cell starch degradation and stomatal opening.