There is now much evidence that the reactive oxygen species (ROS) hydrogen peroxide (H2O2) plays an important role in a number of physiological responses, including stomatal closure. H2O2 is generated in stomatal guard cells in response to drought stress, increased concentrations of abscisic acid (ABA), ozone and also in response to elicitor/pathogen challenge. Generation of H2O2 occurs via the AtrbohD/F subunits of the NADPH oxidase complex. In recent work we have shown that the plant hormone ethylene, known to influence numerous processes such as fruit ripening, senescence, defence responses and seedling growth, also mediates stomatal closure in intact Arabidopsis leaves. Using a combination of genetics and physiological tools, we have demonstrated that ethylene-induced stomatal closure is dependent on H2O2 synthesis via AtrbohF. Guard cells of the ethylene receptor mutants etr1–1 and etr1–3 are insensitive to ethylene, but not to ABA. Moreover stomata of the ethylene signalling ein2-1 and arr2 mutants do not close in response to ethylene, but do generate H2O2 following ethylene treatment. In addition, we have also observed that whilst ethylene alone can cause closure, ethylene in the presence of ABA does not cause stomatal closure in leaves. These data demonstrate that plant hormones mediate their effects in guard cells via complex interplay with redox signalling pathways.
|Journal||Comparative Biochemistry and Physiology A - Molecular & Integrative Physiology|
|Publication status||Published - 2007|