华南师范大学：《植物生理学》课程教学课件（PPT讲稿）第8章 植物生长物质（图解）

Figure8-0CharlesDarwin- This portrait was made shortly after Darwinreturned to England from his voyage around the world.(TheGrangerCollection,NewYork)

Figure 8-0

4-day-oldDarwin:(1880)From experiments onLightoatseedlingcoleoptilephototropisrn,Darwinconciudedin188oColeoptitethata growth stimulusTsproducedinthecoleoptileSeedtip and is transmitted to thegrowthzone.IntactseedlingTip of coleoptileOpaguecap1cm(curvature)excisedontip(no curvature)(no curvature)RootsBovsen-Jensen(1g13)in1913,PBoysen.Jensendiscovered thatthe growthstimutuspasses throughgeiatinbutnotthroughWater-impermeable barrierssuchasmica.Mica sheetMica sheetTipremovedGelatinNormalinsertedinsertedbetweentipphototropicon darksideon lightsideand coleoptileCurvature(no curvature)(curvaturo)stumpremainspossiblePaal(1919)in1919,A.Paalprovidedevidence that the growthpromoting stimulusproducedinthetipwaschemicalinnature.TipremovedTip replacedGrowth curvatureon oneside ofdevelopswithoutcoleoptilestumpa unllateral lightstimulusWent (1926)in19z6.FW.Wentshowedthatthe activegrowth-promoting substance candiffuse intoagelatin blockHe aliso devised acoleoptile-bondinaassayforquantitativeauxinanalysisColeoptiletipsTips discarded:gelatinEach gelatinColeoptile bends inongelatincutupintosmallerblockplacedontotal darkness; angleblocksone side ofof curvature cancoleoptilestumpbe measured20(satajanean)(sabap) anein)2015151010n5O2468100.050.100.150.200.250.30NumberofcoleoptileIAAingelatinblock(mg/L)tips ongelatinFigure 8-1FIGURE 19,Tsearch

Figure 8-1

ciCH2-COOHCH,-COOHCH2-CH2-CH,-COOHNHHHIndole-3-aceticacid4-Chloroindole-3-aceticacidIndole-3-butyricacid(IAA)(4-CI-IAA)(IBA)FIGURE19.3Structure of three natural auxins.Indole-3-aceticacid (IAA)occurs inall plants,but other related compounds inplantshaveauxin activity.Peas,forexample,contain4-chloroindole-3-aceticacid.Mustardsand corn contain indole-3butyric acid (IBA)Figue 8-2

Figue 8-2

IAA1.lAAentersthecell eitherPlasmapassivelyintheundissociatedmembrane609089form(IAAH)orbysecondaryMLactivecotransportintheH+Permeaseanionicform(IAA-)HtHt-cotransportIAAYIAAHApex2H+CellwallK1IAAHPH5CytosolATPATP2.The cell wall ismaintained★H+个IAA3.Inthecytosol,whichhasaatanacidicpHbytheactivityneutral pH,theanionicformof theplasma membraneH+ATP(IAA)predominates.ATPase.PH7,★H+VacuoleATP★Ht★1IAA4.Theanions exitthe cell via000000000auxinanioneffluxcarriersthatareconcentratedattheL?4*basal endsofeachcell intheBaseIAAlongitudinalpathway2H+FIGURE19.13ThechemiosmoticmodelforIAAH4polar auxin transport.Shown hereis one cellin acolumn ofauxin-transporting cells.Figure 8-5(FromJacobsandGilbert1983.)AfP

Figure 8-5

(A)(B)(C)(D)Indole-3-pyruvicacidpathwayCOOHNH2HTryptophan(Trp)*TrpTrpdecarboxylasemonooxygenaseTrptransaminaseCOOHIANTAMOHNOHNH2HIndole-3-pyruvicacid (IPA)HIndole-3-acetaldoximeTryptamine(TAM)IPA1decarboxylaseBacterial pathwayAmineoxidaseNH2H工HIndole-3-acetaldehyde(iAld)Indole-3-acetamide (IAM)Indole-3-acetonitrile(lAN)IAlddehydrogenaseNitrilaseCOOH*IAMhydrolaseHIndole-3-aceticacid (IAA)FIGURE19.6Tryptophan-dependentpathwaysofIAAbiosynthesisinplantsandbacteria. The enzymes that are present only in bacteria are marked with an asterisk.Figure 8-6(AfterBartel1997.)

Figure 8-6

A)pecarb.OmninorpathwayaCOOHPeroxidaseNNHHindole-3-acetic acid3-Methyleneoxindole(B)Nondecarboxylation pathwaysConjugationBiAspartateindole-3-acetylaspartateNHAiAspartateNHDioxindole-3-acetylaspartateCOOHHFigure 8-7Oxindole-3-aceticacid(OXIAAFigure 19.11BiodegradationoflAA.(A)Theperoxidaseroute(decarboxylationpathway)piaysareiativeiyminorrole.(B)Thetwonondecarboxyiationroutes ofiAAoxidative degradation.A and B,are themostcommonmetaboiicpathways.(After Tuominenet al.1994.)

Figure 8-7

1.Intheabsence3.Inthepresenceof5.IAA-inducedoflAA,theauxin,AUX/AAdegradationofthetranscriptionproteinsaretargetedAUxiAAproteinsfactor,ARF,formsfordestruction byanallows active ARFinactiveIAAactivated ubiquitinhomodimerstoheterodimers withligase.form.AUX/IAAproteins.SignalActiveARFtransductionInactiveARFhomodimerpathwayheterodimerARFARFARFActivationofAUXIAADNAubiquitin ligaseTGTCTCCTCTGTPalindromicAuxREATPUbiquitin6.TheactiveARFAUXiIAAandhomodimersbindtoother earlygenespalindromicAuxREsin4.TheAUXIAAthepromotersofthe2.Inactive hetero-proteins aretaggedUbiearlygenes,activatingdimersblockthewithubiquitinandtranscription,transcriptionofthedegradedbytheAUXIAAearly auxingenes.26Sproteasome.AUXllAAandThere is no auxinother earlygenesresponse.8.The stimulationof AUXlIAAgenesintroducesaAuxin-mediatednegativefeedbackgrowth/developmentloop.Figure 8-9Proteasome7.Transcriptionofthe early genesinitiatestheauxinresponse.FIGURE19.41Amodel forauxin regulation of transcriptionalactivation of earlyresponsegenesbyauxin.(AfterGrayetal200l.)

Figure 8-9

Figure 8-10-1Auxin and root development on stemcuttings.(Left)Many adventitious roots developed on ahoneysuckle (Lonicera fragrantissima)cuttingplaced in asolution with a high concentration of synthetic auxin.(Middle)Fewerrootsdevelopedin alowerauxinconcentration.(Right)The cuttingplaced in water (noauxin) served as a control and did not form roots in thesame time period.Joe Eakes,Color Advantage/VisualsUnlimited)

Figure 8-10-1

Turgorpressure stretchesweakenedcell wall.HOAuxinbindstoplasmaActivatedprotonpumpsmembranereceptors.transportHtoutofcellcell wallplasmamembraneATP-H+ATPcytoplasmATPH+4receptor.ATPATP+H+H+auxinAuxinmodeofaction.Afterauxinbindstoareceptor,thecombinationstimulatestheprotonpumpsothathydrogenions (H')aretransported outofthecell.Theresultingacidity causes the cell walltoweaken,andthe electrochemicalgradient causes solutesto enterthecell.Waterfollowsbyosmosisandthecell elongatesFigure 8-10-2

Figure 8-10-2

StageOppPLASTIDGGPPenf.onaidinhosnhateeneO1Stage 2COOHCHOOOHCH,COOHOOHCOOHent-KaureneGA-aldehydeGAGAsENDOPLASMICRETICULUMStage3CYTOSOLCThethree stagesofgibberellinbiosynthesis.InFIGURE20.6stage1,geranyigeranyidiphosphate(Gcrp)isconvertedtoCOOHent-kaurenevlacopalyidiphosphate(Cpp)inplastids.InCOOHstage2,whichtakesplace ontheendoplasmicreticulum,GA(R-H)enf-kaurereSconvertedtoGAorCAadependingonGA(ROH)atcarbon13.InmostwhethertheCAishydroxylateplants theT3-hydroxvlationpathwaypredomintes,thoughthonon-13-oHpathwayisinArubidopsisandsomeothersGA20-oxidasecytonolGAiaorGAathemainpathwaystaeRThisconversionprceedswithaareconvertedotherGAs2IntheIa-hydroxvlationseriosofoxidationsatcarDrHOCpathway this leads tothe production of GA2gGAap.isthenoxidizedtotheactivegibberellin,GAbyaSp-hydroxyla-tion reaction(thu non-T3OH equivalent is GAFinallyCOOHhydroxylationatcarbon2convertsGAanand GA,totheCOOHinactiveformsCAaoatdGArespectivelyGAIS-OL(R=H)GA4-OL(R-OH)GAZ0-oxidaseACLiveGAGAoxidaseGA20-oxidaseHCOOHCOOHCOOHGA(RH)GA.(R-H)COOHGA(R=OH)GA20(R=OH)GA24(R-H)GA(R-OH)GA2-oxidaseGA2-oxidaseinactivation1FFigure 8-13HOHCHCCOOHCOOHGA(R-H)GASI(RWH)GA(R-OH)GA2(R=OH)

Figure 8-13