Abstract:
Using the abaxial epidermis of Vicia faba as materials, the roles of ethylene and H2O2 in light/dark-regulated stomatal movement were studied. The results were as follows: (1) ACC and ethrel had not obvious effect on stomatal aperture in light, but stomatal opening was significantly induced by ACC and ethrel in darkness. The results suggest that the level of ethylene in guard cells is higher in light and lower in darkness, it is possible that the light/dark-regulated stomatal movement is mediated by ethylene in guard cells. (2) Vc, CAT and DPI, had not any effect on stomatal aperture in light, but they significantly promote stomatal opening in darkness. The results imply that the level of H2O2 in guard cells is lower in light and higher in dark, it is possible that the light/dark-regulated stomatal movement is mediated by the level of H2O2 in guard cells. (3) The level of endogenous H2O2 in guard cells was greater in dark than in light, which is accordance with the results of epidermal strip bioassay. All these prove that light/dark-regulated stomatal movement was definitely related to the contents of H2O2 in guard cells; (4) The effects of ethephon on the contents of H2O2 in guard cells are unconspiuous in light, while the level of H2O2 was significantly reduced by ethephon in darkness. The results indicate that ethylene promote stomatal opening through reducing the H2O2 contents of guard cells in dark, and ethylene effect in light/dark-regulated stomatal movement occurs at upstream from H2O2.
