Inhibition of dark-induced stomatal closure by fusicoccin involves a removal of hydrogen peroxide in guard cells of Vicia faba.
Fusicoccin (FC) treatment prevents dark-induced stomatal closure, the mechanism of which is still obscure. By using pharmacological approaches and laser-scanning confocal microscopy, the relationship between FC inhibition of dark-induced stomatal closure and the hydrogen peroxide (H₂O₂) levels in guard cells in broad bean was studied. Like ascorbic acid (ASA), a scavenger of H₂O₂ and diphenylene iodonium (DPI), an inhibitor of H₂O₂-generating enzyme NADPH oxidase, FC was found to inhibit stomatal closure and reduce H₂O₂ levels in guard cells in darkness, indicating that FC-caused inhibition of dark-induced stomatal closure is related to the reduction of H₂O₂ levels in guard cells. Furthermore, like ASA, FC not only suppressed H₂O₂-induced stomatal closure and H₂O₂ levels in guard cells treated with H₂O₂ in light, but also reopened the stomata which had been closed by darkness and reduced the level of H₂O₂ that had been generated by darkness, showing that FC causes H₂O₂ removal in guard cells. The butyric acid treatment simulated the effects of FC on the stomata treated with H₂O₂ and had been closed by dark, and on H₂O₂ levels in guard cells of stomata treated with H₂O₂ and had been closed by dark, and both FC and butyric acid reduced cytosol pH in guard cells of stomata treated with H₂O₂ and had been closed by dark, which demonstrates that cytosolic acidification mediates FC-induced H₂O₂ removal. Taken together, our results provide evidence that FC causes cytosolic acidification, consequently induces H₂O₂ removal, and finally prevents dark-induced stomatal closure.
She
Xiao-Ping
XP
College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China. shexiaoping@snnu.edu.cn
Huang
Ai-Xia
AX
Li
Jin
J
Han
Xi-Zhu
XZ
D020148:Butyric Acid / Q000494:pharmacology; D003624:Darkness; D006027:Glycosides / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D054046:Plant Stomata / Q000187:drug effects* / Q000502:physiology; D031307:Vicia faba / Q000187:drug effects / Q000502:physiology*
D006027:Glycosides; D020148:Butyric Acid; C007808:fusicoccin; D006861:Hydrogen Peroxide