Phosphatidylinositol 3 - Phosphate In The Uv-b Radiation, Ethylene, Or Dark-induced Stomatal Closure In The Role

Previous study has indicated that guard cell generate reactive oxygen species in response to abscisic acid by NADPH oxidase,which leads to stomatal closing.Our laboratory research had proved that cell-wall peroxidase is an enzyme responsible for H₂O₂ generation and stomatal closure in UV-B-treated guard cells,ethylene also could induced H₂O₂ by cell-wall peroxidase,it is defferent from ABA-induced H₂O₂ in guard cells.We still found that dark could induced H₂O₂ generation by NADPH oxidase。In addition,studies also show that PI3P play a role in ABA-induced H₂O₂ generation,the NADPH oxidase complex is responsible for H₂O₂ generation,and is activated by the binding of PI3P to one of the components.However,there is little information available about whether the signal molecule PI3P is also involved in the UV-B,ethylene,or dark-induced stomatal closure. Furthermore,it is also not clear the relationships between PI3P and H₂O₂ in these pathways.NO,which generated by NOS in guard cells,act as second messengers to mediate UV-B, ethylene,dark-induced stomatal closure.However,it is not clear whether PI3P involves in NO generation in guard cells.In order to further understand the signal transduction network in guard cells,we mainly investigated the role of PI3P in UV-B,ethylene or dark-induced stomatal closure and the relationships between PI3P and H₂O₂ or NO in Vicia faba by epidermal strip bioassay and laser-scanning confocal microscopy.The main results were followed:1.PI3P is a product of phosphatidylinositol 3-kinase(PI3K),PI3K inhibitor wortmannin(WM) or LY294002(LY) inhibited UV-B-induced H₂O₂ generation and stomatal closure.In addition,H₂O₂ partially rescues the inhibitory effect of WM or LY on UV-B-induced stomatal closure.This result showed that PI3P involves in UV-B-induced stomatal closure.Cell-wall peroxidase has been suggested to be a H₂O₂-generating enzyme during UV-B signaling in guard cells,the inhibitory effect of WM or LY on UV-B-induced H₂O₂ generation indicates that PI3P involves UV-B-induced stomatal closure through effecting H₂O₂ generation by cell-wall peroxidase.2.PI3K inhibitor WM or LY inhibited UV-B-induced endogenous NO generation in guard cells. In addition,the inhibitory effects of WM and LY on UV-B-induced stomatal closure could be recovered significantly by exogenous sodium nitroprusside(SNP,exogenous NO donor) treatment.It showed that PI3P involves in UV-B-induced NO generation,NOS has been suggested to be a NO-generating enzyme during UV-B signaling in guard cells.It showed that PI3P involves UV-B-induced stomatal closure through effecting NO generation by NOS.3.PI3K inhibitor WM and LY inhibited ethlene-induced stomatal closure and H₂O₂ generation in guard cells.In addition,the inhibitory effects of WM and LY on ethlene-induced stomatal closure and H₂O₂ generation could be reversed significantly by exogenous H₂O₂ treatment.It showed that PI3P involves in ethlene-induced stomatal closure and H₂O₂ generation in guard cells.4.PI3K inhibitor WM or LY inhibited ethlene-induced endogenous NO generation in guard cells.In addition,the inhibitory effects of WM and LY on ethlene-induced stomatal closure could be recovered significantly by exogenous SNP treatment.It showed that PI3P involves in ethlene-induced NO generation.It showed that PI3P involves ethlene-induced stomatal closure through effecting NO generation in guard cells.5.PI3K inhibitor WM and LY inhibited dark-induced stomatal closure and H₂O₂ generation in guard cells.In addition,the inhibitory effects of WM and LY on dark-induced stomatal closure and H₂O₂ generation could be reversed significantly by exogenous H₂O₂ treatment.It showed that PI3P involves in dark-induced stomatal closure and H₂O₂ generation.NADPH oxidase has been suggested to be a H₂O₂-generating enzyme during dark signaling in guard cells,the inhibitory effect of WM or LY on dark-induced H₂O₂ generation indicates that PI3P involves dark-induced stomatal closure through effecting H₂O₂ generation by NADPH oxidase.6.PI3K inhibitor WM or LY inhibited dark-induced endogenous NO generation in guard cells. In addition,the inhibitory effects of WM and LY on dark-induced stomatal closure could be recovered significantly by exogenous SNP treatment.It showed that PI3P involves in dark-induced NO generation.It showed that PI3P involves dark-induced stomatal closure through effecting NO generation in guard cells.