Systemic-acquired-resistance

SystemicacquiredresistanceDefinesystemicresistanceandsomehistoryAssociatedmolecularchangesRoleofSAandothersignalingmoleculesRoleofNPR1(non-expresserofpathogenesisrelatedgenes1)SystemicacquiredresistanceWhatdoweknowaboutsystemicacquiredresistance?SystemicacquiredresistanceSystemicacquiredresistancewasfirstrecognizedasasignificantphenomenonintheearly1900s.Atthattime,itwasrecognizedthatinfectionofplantswith“necrotizing”pathogens(causingHR)oftenresultsinenhancedresistancetosubsequentinfectionsbyavarietyoffungal,bacterialandviralpathogens.Thisphysiologicalimmunitywastermedsystemicacquiredresistance(SAR).SARconfersabroadspectrumtypeofresistanceSARiseffectiveagainstsomebutnotallpathogens:Tobacco:Phytophthoraparasitica,Cercosporanicotianae,Peronosporatabacinatobaccomosaicvirus,tobacconecrosisvirus,Pseudomonassyringaepv.tabaci,ErwiniacarotovoraNoteffectiveagainst:BotrytiscinereaorAlternariaalternataArabidopsis:PhytophthoraparasiticaturnipcrinklevirusPseudomonassyringaepv.tomatoDC3000SystemicacquiredresistancewasassociatedwiththecoordinatedinductionofasetofSARgenesencodingproteinsknownasPathogenesis-related(PR)proteins(VanLoonandGianinazzi(early1970s).(1979)WhitefoundthatacetylsalicylicacidapplicationsufficienttoinducePRgeneexpressionandenhancedresistancetotobaccomosaicvirusintobaccoplant.Discoverycameouttheinterestindevelopingchemicalcontrolmethodsforviralinfection.AfterthatseveralgroupswentontoshowthatsalicylicacidapplicationontobaccoleavesmimicspathogeninducedexpressionofPRgenesandpathogenresistanceintreatedtissues.(1990)TwogroupsoneledbyKlessigandRaskinandanotherledbyMetrauxfoundthatsalicylicacidaccumulatesincucumberandtobaccoplantspriortopathogeninfection,butbeforetheonsetofresistance.Theworkbytheseandmanyothersledtothehypothesisthatsalicylicacid(SA)istheendogenoussignalmoleculethatisrequiredfortheinductionofsystemicacquiredresistance.(1993/1994)ThegroupheadedbyRyalsmadetobaccoplantsthatcouldnotaccumulateSAandfoundthattheseplantsweredefectiveintheirabilitytodevelopsystemicacquiredresistance.ThisworkdemonstratedacentralroleforSAinestablishingsystemicacquiredresistance.ThegroupalsodemonstratedthatthesetobaccoplantsweredefectiveintheirabilitytoaccumulatePRproteins.(1997)CloningofNPR1,akeyregulatorofSARSomekeyeventsinunderstandingregulationofSARPR(Pathogenesis-Related)proteinsProteinssecretedpredominantlyintointercellularspacesinresponsetowoundingorinfection.SolubleatpH3Basichomologsalsofound(invacuole).Proteinaseresistant(butnotproteinaseinhibitors).Somearedevelopmentallyexpressedaspartofnormalplantdevelopmentinabsenceofwoundorinfection(e.g.flowering).PRproteinsfirstidentifiedasmajorproteinsinducedbynecrotizingpathogens(pathogensthatinducedthehypersensitiveresponse)AcidicgelBasicgelAlltobaccoPRproteinsPRproteinsProteinsfirstisolatedfromapoplastofTMV-infectedtobacco.Inducedbymanyotherpathogens.SomePRproteinsarealsoinducedbyabioticstresses.TraditionalPRproteingelsoldnomenclaturePRgenesinducedafterHRorSAtreatmentWhatdoPRproteinsdo?Selsetal.(2008)PlantPhysiol.Biochem.46:941-950AlsovanLoonetal.(2006)Annu.Rev.Phytopathol.44:135-162Somearemembersoflargegenefamilies–e.g.PR-1vanLoonetal.(2006)Annu.Rev.Phytopathol.44:135-162ConstitutiveexpressionofchitinasePRproteinconfersresistancetoRhizoctoniasolaniBrogueetal.(1991)Science254,1194-1196ControlLine37323023832937354818daysaftergrowthinR.solani-ladensand11d.a.g.inR.solanisandApplicationofsalicylicacidmimicsSAR(1979)Whitefoundthattheapplicationofaspirin,salicylicacid,andbenzoicacidresultedinenhancedresistancetoTMV.Used3tobaccocultivarsthatcontainedtheNresistancegenethatconfersHRtoTMV.Found90%reductioninlesionnumberintreatedleavesversuswatercontrol.LesionsobtainedaftersecondinoculationSASAaccumulationisassociatedwithacquisitionofresistanceScience(1993)261,754-756.CentralroleofSAinSARPR-1PR-2PR-3PR-1mRNACentralroleforSAindefensecontinuedEnhancedsusceptibilityLossofresistanceINAinducesresistanceinpresenceofnahGWhatisthemobilesystemicsignal(s)forSAR?Methylsalicylate–meSASABP2(meSAesterase)isrequiredforSARParketal.Science318:113-116Whatisthemobilesystemicsignal(s)forSAR?Methylsalicylate–meSASAMT1(SAmethyltransferase)isrequiredforSARParketal.Science318:113-116Whatisthemobilesystemicsignal(s)forSAR?Methylsalicylate–meSAmeSAinducesSARinsystemictissuesexpressingSABP2(MeSAesterase)Parketal.Science318:113-116Aroleofglycerol-3-phosphateinSARReducedSARingly1andgli1mutantsG3PlevelsincreaseinresponsetopathogeninlocalandsystemictissuesChandaetal.(2011)Nat.Genet.43:421-427ExogenousG3PrestoresSARingli1andgly1plantsAroleofglycerol-3-phosphateinSARChandaetal.(2011)Nat.Genet.43:421-427G3PconferredSARisdependentonDIR1DIR1isaproposedlipidtransporterproteinChandaetal.(2011)Nat.Genet.43:421-427DIR1isneededforG3PtransportSignalingstepsbetweenSAandPRproteinexpressionanddiseaseresistance.TheArabidopsisNPR1GeneThatControlsSystemicAcquiredResistanceEncodesaNovelProteinContainingAnkyrinRepeatsHuiCao,JaneGlazebrook,JosephD.Clarke,SigridVolko,andXinnianDong(1997)Cell88,57–63,Previously:LinkedaPRproteinpromote