Functional Analyses On Regulator Of RGS In ABA-and NO-mediated Stomatal Movement In Arabidopsis Thaliana

G protein signaling is one of core content in Molecular Biology at present.The same process in G protein signaling is GTPase cycle:GTP/GDPexchange and GTP hydrolysis.When A Specific ligand connect with the GPCR ,activated GPCR stimulates the exchange of GDP for GTP on Gαto initiate heterotrimer dissociation and activation of effector proteins that, in turn, initiate a cascade of cellular signaling events. RGS proteins are relatively new actors on this stage. All family members contain a signature RGS domain responsible,because of this structure ,nearly all RGS family members have a function as GAP activity.The regulators of G protein signaling(RGS proteins) participate in this process by binding directly to activated Gα-GTP to serve as GTPase-activating proteins (GAPs), which limit the lifetime of Gα-GTP and terminate signaling event(s).Stomatal movement invovels complicated signaling transduction network,such as ABA-,G-protein and NO-mediated signaling pathways.To reach the functions of the regulators of G protein signaling(RGS proteins) on stomatal movement have significant meanings,Which will show a clearer view in the signal transductions.In this study, by using corresponding Arabidopsis wild type Col, over express type 35S:RGS, rgs1-2, gpa1-4, abi1, aba3, abh1 ,double mutants abi1rgs1-2, aba3rgs1-2, abh1rgs1-2. We studied the roles of AtRGS1 in ABA-mediated stomatal movement and in the regulation of stomatal development. The major results are showed as follows:1) Enogenous ABA induces stomatal closure in Arabidopsis wild type, AtGPA1 protein plays a positive role in the stomatal closure promoted by ABA, and it is on the upstream of NO. AtRGS1 may acts as a double roles in the ABA signalings: A negative function in G-protein-signalings at the early ABA signal.A positive role in an other branch pathway–NO-signalings which also induces the closure in ABA-mediated stomatal closure process. ABI1 protein also work as a positive number in the closure induced by ABA, it is in the NO-signaling or positive in the closure process with other parterners.2) In Arabidopsis wild type, enogenous ABA can inhibite stomatal opening. AtRGS1 plays a negative role in this process, but not a essential factor. ABI1 protein is direct member and active in this inhibition.3) Enogenous NO induces Arabidopsis wild type stomatal closure, and this process is mediated by AtRGS1 and ABI1,They are the essential factors in NO signalings, positive in the closure moments.4) Enogenous NO inhibite stomatal opening In Arabidopsis wild type. ABI1 is the essential factor in this inhibition as a negative one.5)Both the ABA and the NO effects on stomatal closure and opening are genetically independently, they may be controlled by different mechanism and procedure.6) In Arabidopsis guard cells, AtGAP1 mediates NO synthesis induced by ABA. AtGPA1 plays a positive role in this inducement.