NADPH oxidase in plasma membrane is involved in stomatal closure induced by dehydroascorbate

Stoma is surrounded by two guard cells, and regulates the contents of water and CO2 in plant, its opening and closing was affected by various factors. Recently, dehydroascorbate was found to induce stomata closure and H2O2 generation. However, the mechanism of H2O2 production is not clear. DPI and imidazole inhibit the flavoprotein and the b-type cytochrome components of the NADPH oxidase complex. Application of DPI or imidazole with DHA together impaired stomatal closure and elevation of H2DCF-DA fluorescent intensity induced by DHA in guard cells. CoCl2 and PD98059, as the blocker of calcium channel and the inhibitor of MAPKKK, both impaired stomatal closure induced by DHA. The results suggested that DHA-induced H2O2 generation via activation of NADPH oxidase, and thus resulting in stomatal closure. Moreover, Ca2+ channel and MAPK cascades were involved in stomatal closure induced by DHA.