hotosynthesis植物光合作用.ppt

《hotosynthesis植物光合作用.ppt》由会员分享，可在线阅读，更多相关《hotosynthesis植物光合作用.ppt（85页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、植物生理学PlantPhysiologyBiochemistry&MolecularBiologyofPlantsBobB.BuchananWilhelmGruissemRussellL.Jones植物学报植物生理学植物生理学通信PlantPhysiologyPlantCellPlantSciencePlantaAnnualReviewofPlantPhysiologyandPlantMolecularBiologyPart1Photosynthesis1.1OverviewofPhotosynthesis1.1.1Photosynthesisisabiologicaloxidation-re

2、ductionprocess.Reaction1.1:PhotosynthesisCO2 2+2H2 2A(CH2 2O)+2A+H2 2Oljtang:Reaction1.2:Oxygenic PhototsynthesisCO2+2H2O(CH2O)+O2+H20Reaction1.3:PhotosyntheticsulfurreductionReaction1.3:PhotosyntheticsulfurreductionlCO2+2H2A(CH2O)+2S+H2O1.1.2Inphotosyntheticeukaryotes,photosynthesistakesplaceinthe1

3、.1.2Inphotosyntheticeukaryotes,photosynthesistakesplaceinthechloroplast,aspecializedorganellechloroplast,aspecializedorganelleChloroplast,adouble-membranesystem,consistofanout envelopeand inner envelope.Theinternalmembranesystem,knownasthe thylakoids,containsgranal thylakoidsandstroma thylakoids.The

4、thylakoidmembranesareallinterconnectedandencloseaninternalspace,the lumen.1.1.3Photosynthesisrequiresthecoordinationoftwophases:light1.1.3Photosynthesisrequiresthecoordinationoftwophases:lightreactionsandcarbon-linkedreactionsreactionsandcarbon-linkedreactionsLightreactions:produceO2,ATP,andNADPH.Ca

5、rbonreductioncycle:reduceCO2tocarbohydrateonconsumingtheATPandNADPH.The conception that water oxidation and CO2 reduction were notobligatelylinkedwasfirstadvancedin1930sbyRobertHill.Reaction1.4:HillReaction2H2O+2AO2+2H2A1.2LightAbsorptionandenergyconversion.1.2LightAbsorptionandenergyconversion.1.2.

6、1Lightisabsorbedbypigmentmolecules.1.2.1Lightisabsorbedbypigmentmolecules.PigmentPigment*PigmentPigment*numberofproductsformedphotochemicallyEquation1.2.1:QuantumYield=-Numberofquantaabsorbed1.2.21.2.2AlmostallphotosyntheticorganismscontainAlmostallphotosyntheticorganismscontainchlorophyllorarelated

7、pigment.chlorophyllorarelatedpigment.Plants,AlgaeandCyanobacteria:chlorophyllaorchlorophyllb.Anaerobicphotosyntheticbacteria:bacteriochlorophylla.Chlorophyllshaveaporphyrinringstructurethatcontainsacentral Mg atom coordinated to the four modified pyrrolerings.Chlorophyllmoleculesalsocontainalonghydr

8、ocarbontailthatmakesthemoleculeshydrophobic.Variouschlorophyllsdifferintheirsubstituentsaroundtheringstructure.Biosynthesis of chlorophylls and hemes.Biosynthesis of chlorophylls and hemes.1.2.3 Carotenoids and xanthophylls participate inlightabsorptionandphotoprotection.1.2.4Absorptionspectraofchlo

9、rophyllsandotherphotosyntheticpigments1.2.5 Red algae and Cyanobacteria containaccessorypigmentsthatabsorbgreenlight.1.3Thereactioncentercomplex.1.3.1Reactioncentersareintegralmembraneproteincomplexesinvolvedinconversionoflightenergyintochemicalproducts.1.3.2Reactioncenterscontainbothspecialchloroph

10、ylland electron acceptor molecules involved in energyconversion.1.3.3 The structure of a reaction center from aphotosyntheticbacteriumhasbeendetermined.1.3.4Thekineticsofprimarychargeseparationeventsareunderstoodingreatdetail.1.3.5Oxygenicphotosyntheticorganismscontaintwophotochemicalreactioncenters

11、,PSIandPSII1.3.5.1StructuremodelofthePSIIreactioncenter.1.3.5.2StructuremodelofthePSIreaction1.3.5.2StructuremodelofthePSIreactioncenter.center.1.4ThePhotosysteml1.4.1Aphotosystemcontainsaphotochemicalreactioncenterandmultipleantennae(auxiliarylight-harvestingpigment-proteincomplexes).l1.4.2Mostoxyg

12、enicphotosyntheticorganismscontainchlorophylla/bproteinsastheirprincipalantennae.Table1.4.2Propertiesoflight-harvestingTable1.4.2Propertiesoflight-harvestingchlorophyllproteincomplexeschlorophyllproteincomplexeslComplexChla/bratioGeneMol.Mass(kDa)lLight-harvestingcomplexes(LHC)associatedwithPSlLHC-a

13、2.0-3.1lhca3 20.5l(LHC-680)lhca2 18lLHC-b2.2-4.4lhca1 20l(LHC-730)lhca4 20lLight-harvestingcomplexesassociatedwithPSlLHC-a(CP29)4.0lhcb4 29lLHC-b1.35lhcb1 27-28lLHC-c(CP26)2.9lhcb5 26.5lLHC-d(CP24)1.51lhcb6 241.4.2TheorganizationofpigmentsinPS1.4.2TheorganizationofpigmentsinPSandPSandPS.1.4.3Theligh

14、t-harvestingantennaeof1.4.3Thelight-harvestingantennaeoforganismthatcontainphycobilinsorganismthatcontainphycobilinsReaction1.4.3EnergytransferinaReaction1.4.3EnergytransferinaphycobilisomephycobilisomelPhycoerythin(PC)Phycocyanin(PE)lAllophycocyanin(APC)Chla1.5Organizationofthylakoidmembrane1.5Orga

15、nizationofthylakoidmembrane1.5.1Proteincomplexesofthethylakoidmembrane1.5.1Proteincomplexesofthethylakoidmembraneexhibitlateralheterogeneity.exhibitlateralheterogeneity.1.5.2PhosphorylationofLHC-mayinfluencethedistributionofenergybetweenPSandPS1.6Electrontransportpathwaysinchloroplastmembranes1.6Ele

16、ctrontransportpathwaysinchloroplastmembranes1.6.1Thechloroplastnoncyclicelectrontransportchainproduces1.6.1ThechloroplastnoncyclicelectrontransportchainproducesOO2 2,NADPH,andATPandinvolvesthecooperationofPS,NADPH,andATPandinvolvesthecooperationofPSandPSandPS1.6.2Photosystemstoichiometryvariesbyspec

17、iesand1.6.2Photosystemstoichiometryvariesbyspeciesandisinfluencedbylightenvironment.isinfluencedbylightenvironment.lTable1.6.2Stoichiometryofthephotosystemsindifferentoxygen-evolvingsystemsandinresponsetochangesinlightquality_llSystemPS/PSratiolCyanobacteria0.4lRedalgae0.4lGreenalgae1.4lTobaccomutan

18、tsu/su2.7lPeachloroplastslFromplantsgrowninPSlight(550-660nm)1.2lFromplantsgrowninsunlight1.8lFromplantsgrowninPSlight(660nm)2.31.6.3PS1.6.3PSfunctionsasalight-dependentwater-functionsasalight-dependentwater-plastoquinoneoxidoreductase.plastoquinoneoxidoreductase.Table1.6.3ProteinsubunitsofthePSTabl

19、e1.6.3ProteinsubunitsofthePScorecorecomplexecomplexelHydrophobicsubunitslProteinGeneLocationofgeneFunctionlD1psbAChloroplastReactioncenterproteinlD2psbBChloroplastReactioncenterproteinlCP47psbCChloroplastAntennabindinglCP43psbDChloroplastAntennabindinglCytb559lsubunitpsbEChloroplastUnknownlsubunitps

20、bFChloroplastUnknownlPsbH-PsbNpsbH-psbN ChloroplastUnknownl22kDapsbSNucleusPhotoprotectionlHydrophilicsubunitsl33kDapsbO NucleusOxygenevolutionl23kDapsbPNucleusOxygenevolutionl17kDapsbQNucleusOxygenevolutionl10kDapsbR NucleusUnknown1.6.4OxidationofwaterproducesO2and1.6.4OxidationofwaterproducesO2and

21、releaseselectronsrequiredbyPSreleaseselectronsrequiredbyPSlReaction1.6.4:Oxidationofwaterl2H2OO2+4H+4e-ThepatternofoxygenevolutionisgiveninThepatternofoxygenevolutionisgiveninresponsetoaseriesofshortflashesoflightresponsetoaseriesofshortflashesoflightTheoxygenevolutionapparatusisconsideredtoexistThe

22、oxygenevolutionapparatusisconsideredtoexistinfivedifferentoxidationstates(Sinfivedifferentoxidationstates(So othroughSthroughS4 4)StructureofthemanganeseclusterStructureofthemanganesecluster1.6.5Thecytochrome1.6.5Thecytochromeb b6 6f fcomplextransferselectronscomplextransferselectronsfromreducedplas

23、toquinonetooxidizedplastocyaninfromreducedplastoquinonetooxidizedplastocyaninProtontranslocationviacytochromeProtontranslocationviacytochromeb b6 6f f isisthoughttoinvolveaQ-cyclethoughttoinvolveaQ-cyclelReaction1.6.5:TheQ-cycleinthechloroplastlPQH2+2PCox+2H+stromaPQ+2PCred+4H+lumen1.6.6Pastocyanin,

24、asolubleprotein,links1.6.6Pastocyanin,asolubleprotein,linkscytochromecytochromeb b6 6f f andPSandPS1.6.7PS1.6.7PSfunctionasalight-dependentfunctionasalight-dependentplastocyanin-ferredoxinoxidoreductaseplastocyanin-ferredoxinoxidoreductaseElectronsfromPSElectronsfromPSaretransferredtoNADParetransfer

25、redtoNADP+inthestromainareactionrequiringferredoxininthestromainareactionrequiringferredoxin andand ferredoxin-NADPferredoxin-NADP+reductasereductase1.6.8Specificinhibitorsandartificialelectron1.6.8Specificinhibitorsandartificialelectronacceptorshavebeenusedtostudytheacceptorshavebeenusedtostudythec

26、hloroplastelectrontransportchainchloroplastelectrontransportchainD11.6.9Chloroplastsalsocontainacyclic1.6.9Chloroplastsalsocontainacyclicelectrontransportchainelectrontransportchain1.7ATPsynthesisinchloroplasts1.7ATPsynthesisinchloroplastsl1.7.1ElectrontransportandATPsynthesisarecoupledinvivo.l1.7.2

27、ChloroplastssynthesizeATPbyachemiosmoticmechanismdrivenbyaprotongradient.lInthe1960s,PeterMitchellproposedthechemiosmoticmodeltoexplainATPsynthesisinchloroplastsaswellasinmitochondria.Theexperimentalverificationofthishypothesisinthe1960sand1970sresultedinMitchellsreceivingthe1978NobelPrizeinchemistr

28、y.1.7.3ExperimentalmanipulationoflumenalandstromalpHcan1.7.3ExperimentalmanipulationoflumenalandstromalpHcanpromotelight-independentADPphosphorylationinchloroplasts.promotelight-independentADPphosphorylationinchloroplasts.lAcid-basePhosphorylationlChloroplastswerefirstincubatedataboutpH4,allowingthe

29、mtoestablishthispHinternally.ThechloroplastsuspensionwasthenrapidlyadjustedtopH8,establishinganartificialpHgradientacrossthemembrane.ThisartificialpHgradientpromotedATPsynthesisuntilitwasdischargedandthepHdifferencewasinsufficienttodriveADPphosphorylation.lAcid-baseATPsynthesisrequirednolightandwasi

30、nsensitivetoelectrontransportinhibitor,suchasDCMU,indicatingthatapHgradientalonewassufficienttodriveATPsynthesis.1.7.4ThemostwidelyacceptedmechanismofATPsynthesisis1.7.4ThemostwidelyacceptedmechanismofATPsynthesisistheso-calltheso-callbindingchangemechanismbindingchangemechanismproposedoriginallybyP

31、aulproposedoriginallybyPaulBoyer(aco-recipientof1997NobelPrizeinchemistry)Boyer(aco-recipientof1997NobelPrizeinchemistry)1.8CarbonreactionsinC1.8CarbonreactionsinC3 3plantsplantslMostplantsproduceathree-carboncompound,3-phosphoglycerate(3-PGA),asthefirststableproductinthemultistepconversionofCO2into

32、carbohydrate.Thisfunctionallydefinedgroup,whichincludesmostcropplants,isreferredtoasC3plants.TheCalvincycleisdividedintothreephases:carboxylation,TheCalvincycleisdividedintothreephases:carboxylation,reduction,andregeneration.reduction,andregeneration.1.9C1.9C4 4plantscontaintwodistinctCOplantscontai

33、ntwodistinctCO2 2-fixingenzymes-fixingenzymesandhavespecializedfoliaranatomyandhavespecializedfoliaranatomy1.9.1TheC4pathwayincreasestheconcentrationof1.9.1TheC4pathwayincreasestheconcentrationofCOCO2 2inbundlesheathcell.inbundlesheathcell.ThebundlesheathchloroplastlacksstackedthylakoidsThebundleshe

34、athchloroplastlacksstackedthylakoidsandcontainslittlePSandcontainslittlePS1.9.2VariationsinC4photosynthesis1.9.2VariationsinC4photosynthesislThreevariationsofC4photosynthesisareknown,differingintheC4acidstransportedbetweenmesophyllandbundlesheathcellsaswellasinthemechanismofdecarboxylationinthebundl

35、esheathcell.lThevariationsarenamedonthebasisofthedecarboxylaseenzymesinthebundlesheathcells.1.9.4OntogenyofC4patterns1.9.4OntogenyofC4patternslInthedevelopmentofmostC4leaves,theexpressionofC4genesdoesnotoccuruntilKranzanatomyhasbeenestablished.lTheappearanceofC4activitieshasbeencomparedinleaves1-5of

36、maizeseedlings:thefirstleafinitiated(leaf1)wasmoreC3incharater,whilethelastmeasured(leaf5)wasfullyC4.lSomestudiesshowedthatcallusculturesderivedfromC4plantsdonotexhibitafunctioningC4pathwayuntilcellsorganizeintoshootsandvasculardevelopmentisunderway.lPhysiologicalmeasurementssuggestthattheobservedpa

37、tternsofgeneexpressionreflectthefunctionoftheC4carbonfixationpathwaynearveinsandtheC3pathwayatmoredistantlocations1.9.3C3-C4intermediateplantsandevolutionof1.9.3C3-C4intermediateplantsandevolutionofphotosyntheticsystemphotosyntheticsystemlSpecieswithanatomicalandphysiologicalcharacteristicsintermedi

38、atebetweenC3andC4existinmanyplantfamilies.ThecharacteristicsoftheseintermediatespeciesrepresentevolutionarystepsbetweenC3andC4plants,althoughallpointoutthatC3-C4intermediatephysiologyneednotresultfrompartialfunctionoftheC4system.lCertaingenera(Flaveria)containC3,C4,andC3-C4intermediatespeciesandther

39、eforeprovidetheopportunitytostudytheconcordanceofchangesinanatomywithphysiologyamongrelatedspecies.lTaxonomicalandphylogeneticalstudiessuggestthatCAMandC4plantswerederivedfromC3plantsandthetransitionsoccurredmanytimesindiversetaxaduringthecourseofevolution.AdrasticdeclineinatmosphericCO2levelduringt

40、helateCretaceousperiod(65-85millionyearsago),atimeofmajorexpansionoftheangiosperms,hasbeenproposedtoaccountfortheincreaseofC4plants.1.9.5Thechangeofphotosyntheticpathway1.9.5ThechangeofphotosyntheticpathwaylC4carbonfixationpathwayhasbeenfoundinsomeC3plants.lC3pathwaycouldbecomeadominantpathwayinC4pl

41、antsduringtheprocessofsenescence.lManyaquaticandamphibiousC4speciesexhibitaremarkabledevelopmentalplasticitythatpermitsmodulationofC3vsC4fixationalongwithvariationsinleafanatomydependingonhabitat.(Eleocharis)lThesubmersedmonocotHydrilla verticillatatypicallyexhibitsC3character,butexposuretolow(CO2)i

42、nducesaC4systeminwhichtheC4andCalvincycleco-existinthesamecell.1.9.6MolecularengineeringofC4enzymesinC31.9.6MolecularengineeringofC4enzymesinC3plantsplantslPEPClEffectsofoverexpressionofPEPConphotosynthesisarecontroversial.Attemperaturesoptimalforplantgrowth,practicallynodifferenceintherateofCO2assi

43、milationandCO2compensationpointwasobservedintransgenictobaccoexpressingthemaizePEPCgene.lIntransgenicriceplantsexpressingthemaizePEPCgene,therateofCO2fixationwasnotalteredsignificantly,butO2inhibitionofnetCO2assimilationwasmitigatedwithincreasingactivityofPEPC.PPDKPPDKlTransgenicArabidopsis,potato,r

44、iceexpressingthemaizeC4-specificPPDKgene,andtransgenictobaccoexpressingaPPDkgenefromtheCAMplantshowednochangesinphotosyntheticcharacteristics.lFutureperspectiveslExperimentswithtransgenicplantshavereinforcedthefactthattheC4mechanismisafinelytunedmetabolic“machine”wherebothahighdegreeofprecisioningen

45、eexpressionandstructuralmorphologyworktogethertoconcentrateCO2efficientlyatthesiteofRubisco.1.10CAMmetabolisminvolvesthetemporalseparation1.10CAMmetabolisminvolvesthetemporalseparationofCO2captureandphotosynthesisofCO2captureandphotosynthesis1.11Photorespiration1.11PhotorespirationlPhotorespirationi

46、sassociatedwithlight-dependentoxygenuptakeandCO2evolutioningreenplanttissues.lOxygenaseactivityofRubiscocatalyzestheinitialstepofphotorespiration.lPhotorespiratoryreactionsoccurinthreeorganelles:chloroplast,peroxisome,andmitochondrion.lProductionofammoniaduringphotorespirationrequiresanancillarycycl

47、eforitsefficientreassimilation.lPhotorespirationincreasestheenergycostsassociatedwithphotosynthesis.lExperimentalmeasurementsofphotorespiratorycarbonflux,whichuseoxygenisotopestodiscriminatebetweenphotosyntheticCO2uptakeandphotorespiratoryCO2efflux,indicatethattherateofphotorespiratoryCO2releaserang

48、esfrom18%to27%ofthephotosyntheticcarbonfixationrate.PhotorespirationmayinfluenceresponseofC3plantstoPhotorespirationmayinfluenceresponseofC3plantstofutureclimaticevents.futureclimaticevents.RoleofphotorespirationinplantsRoleofphotorespirationinplantslTheoxygenaseactivityofRubiscoisconsistentwiththeenzymesanaerobicorigins.Phosphoglycolateformedduringtheoxygenasereactionismetabolizedthroughthephotorespiratorycarboncycletosave75%ofthecarbonintheformofphosphoglycerate.lTheenergyconsumptioninthephotorespirationcanprotectthephotosystemfromthedamageofhighdensityofsunlight.