SnapShot:PlantImmuneResponsePathwaysRalphPanstruga,JaneE.Parker,andPaulSchulze-LefertMax-PlanckInstituteforPlantBreedingResearch,Köln50829,GermanySeeonlineversionforlegendandreferences.978Cell136,March6,2009©2009ElsevierInc.DOI10.1016/j.cell.2009.02.020SnapShot:PlantImmuneResponsePathwaysRalphPanstruga,JaneE.Parker,andPaulSchulze-LefertMax-PlanckInstituteforPlantBreedingResearch,Köln50829,Germany978.e1Cell136,March6,2009©2009ElsevierInc.DOI10.1016/j.cell.2009.02.020RecognitionofMicrobe/Pathogen-AssociatedMolecularPatternsPlantinnateimmunitydependsonthetimelydiscriminationofselffromnonself,which,asinanimalcells,canbeaccomplishedbymembrane-anchoredpatternrec-ognitionreceptors(PRRs).Thesereceptorsmonitortheexteriorspaceformicrobe/pathogen-associatedmolecularpatternsorMAMPs(alsocalledPAMPs)bybindingtothemdirectlyorbyassociatingwithMAMP-bindingproteins.Well-characterizedplantPRRscompriseleucine-richrepeat(LRR)receptor-likekinasessuchastheflagellinreceptorFLS2,itscoreceptorBAK1,andthereceptorforbacterialelongationfactorEF-TucalledEFR.Membrane-boundproteinswithpeptidoglycan-bindingLysMdomains(forexample,CEBiPandCERK1)representPRRsorbindingproteinsforthefungalMAMP,chitin.RecognitionofconservedMAMPsbyPRRstriggersintracellularsignalingviamitogen-activatedproteinkinase(MAPK)cascades(MAPKKK,MAPKK,MAPK).Thisresultsultimatelyintranscriptionalactivationofdefensegenesbyplant-specifictranscriptionalregulatorsincludingmembersoftheWRKYsuperfamily.Executionoftheimmuneresponsereliesinpartontheexocytosispath-wayleadingtovesicle-associatedandSNAREprotein-mediatedfocalsecretionofdefense-relatedproteinsincludingPR-1.A“toxicload”ofantimicrobialcargosuchasthatderivedfromthebiochemicalactivationofnontoxicprecursorscanalsobetranslocatedtotheextracellularspacebymembersoftheATP-bindingcassette(ABC)transporterfamily.AnotherearlyMAMP-triggeredresponseistheextracellulargenerationofreactiveoxygenspecies(O2-andH2O2)bymembrane-localizedNADPHoxidases(RbohD).Incontrast,biosynthesisanddepositiono...
