第十一章植物生長物質(zhì)第三節(jié)赤霉素

第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesisandMetabolismPhysiologicalrolesMolecularmechanismApplicationGA4GA1GA34預(yù)習(xí)提問1：你認(rèn)為下列赤霉素哪個有生物活性？預(yù)習(xí)提問2：你能解釋下下圖中的各種字母縮寫的含義嗎？預(yù)習(xí)提問3：從下圖所示的試驗(yàn)表現(xiàn)了赤霉素的那些生理作用？CKGA3第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesisandMetabolismPhysiologicalrolesMolecularmechanismApplicationDiscoveryofgibberellins惡苗病Bakanedisease(foolishseedling)赤霉菌Gibberellafujikuroi(Sawada)Characteristicelongatedriceseedlingcausedbybakanae關(guān)于赤霉素發(fā)現(xiàn)的幾篇?dú)v史文獻(xiàn)HoriS.1898.Someobservationson"Bakanae"diseaseofthericeplant.Mem.Agric.Res.Sta.(Tokyo)12(1),110-119.YabutaT,SumikiY.1938.Onthecrystalofgibberellin,asubstancetopromoteplantgrowth.JAgricChemSocJapan.14.1526..CurtisPJ,CrossBE.1954.Gibberellicacid.AnewmetabolitefromtheculturefiltratesofGibberellafujikuroi.Chem.Ind.1066.

MacmillanJ,SuterPJ.1958.TheoccurenceofgibberellinA1inhigherplants:Isolationfromtheseedofrunnerbean(Phaseolusmultiflorus).Naturwiss45,46.MacmillanJ,SuterPJ.1958.TheoccurenceofgibberellinA1inhigherplants:Isolationfromtheseedofrunnerbean(Phaseolusmultiflorus).Naturwiss45,46.GA1isthefirstgibberellin

foundinplantGA1isthefirstgibberellinfoundinplant第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesisandMetabolismPhysiologicalrolesMolecularmechanismApplication赤霉素的基本骨架ent-gibberellaneskeleton

赤霉烷骨架赤霉素的種類GibberellinA136

C19赤霉素C20赤霉素

C13非羥化赤霉素

C13羥化赤霉素BiologicallyactiveGAs活性赤霉素的結(jié)構(gòu)特征3β-羥基1，2不飽和鍵2，3不飽和鍵赤霉素的構(gòu)效關(guān)系赤霉素的構(gòu)效關(guān)系無活性赤霉素的結(jié)構(gòu)特征有2β-羥基有三個羧基赤霉素的構(gòu)效關(guān)系GA4GA1GA34活性赤霉素結(jié)構(gòu)的本質(zhì)AffinityforreceptorGID1AbilitytoformacomplexconsistingofGID1,GA,andtheDELLA第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesisandMetabolismPhysiologicalrolesMolecularmechanismApplicationd1d1WTWT+GA1+GA1MutantsofgibberellinbiosynthesisMutantsofgibberellinbiosynthesisMutantsofgibberellinbiosynthesis26GAbiosyntheticsiteandpathwayImportantforregulationofGAbiosynthesis/levelsGAbiosyntheticenzymesarespecificallylocalizedinyoung,activelygrowingbuds,leaves,andupperinternodesGAsaresynthesizedinshootandtransportedtorestofplantviaphloemArabidopsismutantsPeamutantsMaizemutantsBiosynthesisPathwayofGAs（Yamaguchi，2008）(1)ent-copalyldiphosphatesynthase(CPS);(2)ent-kaurenesynthase(KS);(3)ent-kaurene19-oxidase(EKO);(4)ent-kaurenoicacid7-hydroxylase;(5)GA12-aldehydesynthase;(6)GA7-oxidase(GA7ox);(7)GA13-hydroxylase(GA13ox);(8)GA20-oxidase(GA20ox);(9)GA3-hydroxylase(GA3ox);(10)GA2-oxidase(GA2ox)BiosynthesisPathwayofGibberellin1、ThreeStagesofGAsBiosynthesis2、InhibitorsofGAsBiosynthesis3、OrganSpecificityofGAsBiosynthesis4、FactorsaffectGAsBiosynthesisBiosynthesisofgibberellinsStage1Stage2Stage3Stage3早期C13羥化途徑的一條支路LocalizationofGibberellinBiosynthesis赤霉素生物合成和生理作用的器官特異性

OrganSpecificityofGAsBiosynthesis

早期C13羥化途徑及其合成的GA1主要存在于植物的營養(yǎng)生長階段和營養(yǎng)器官中，起著促進(jìn)莖葉生長的調(diào)節(jié)作用； 早期C13非羥化途徑及其合成的GA4/5主要存在于植物的生殖生長階段和生殖器官中，起著促進(jìn)花果發(fā)育和生長的調(diào)節(jié)作用赤霉素生物合成器官特異性的實(shí)例赤霉素生物的合成器官特異性發(fā)芽莖葉生長花器官分化/成熟穗軸/節(jié)間生長營養(yǎng)生長生殖生長ExpressionoftheGAmetabolicgenesinvariousorgansofthewild-typerice.TotalRNAswereisolatedfromvegetativeshootapices(1),leafsheaths(2),leafblades(3),stems(4),roots(5),

immaturepanicles(6),andpaniclesatfloweringtime(7),andquantitativeRT-PCRwasconducted.HistoneH3wasusedasacontrol.(A)RNAgelblotanalysesofOsGA3ox1andOsGA3ox2invariousriceorgans(cultivarAkibare).TotalRNAwasisolatedfromshootapices(SA),stems(St),leafblades(LB),rachis(Ra),unopenedflowers(Fl),elongatingleaves(EL),youngpanicles(YP),andshoots(Sh)..BlotswerehybridizedwithprobesforGA3β-hydroxylases(OsGA3ox1,OsGA3ox2).Approximately10μgoftotalRNAfromeachsamplewasloadedontothegelandstainedwithethidiumbromide(rRNA).赤霉素生物合成器官特異性的分子證據(jù)奇跡稻的秘密sd1Thelevelofgeneexpressionineachtissuesample,asdeterminedbyquantitativePCR,isshownasthenumberofcDNAcopiesper105copiesofUBQ11cDNA.Theorgansanddevelopmentalstagestestedwere,fromlefttorightinthegraph,12-and24-himbibedseeds,2-,5-and10-day-oldseedlings,rootsof5-day-oldseedlings,14-day-oldrosettesandthefollowingorgansfrom35-day-oldplants:caulineleaves,stems,flowerclustersandsiliques.Themeansofthreeexperiments±SEareshown.TranscriptlevelsofGA3ox1–GA3ox4throughoutdevelopmentinArabidopsisMitchumMG,YamaguchiS,HanadaA,KuwaharaA,YoshiokaY,etal.2006.Distinctandoverlappingrolesoftwogibberellin3-oxidasesinArabidopsisdevelopment.PlantJ.45:804–18赤霉素生物合成的影響因素

FactorsaffectGAsBiosynthesis

生長發(fā)育因素developmentalfactors環(huán)境因素enviromentalfactors反饋控制feedbackcontrol與其他激素的相互作用cross-reactionwithotherhormonesPhotoperiodregulationofGA1biosynthesisEnvironmentalconditionsaltertranscriptionofbiosynthesisgenesSpinachplantsundergostemandpetioleelongationonlyinlongdays(LD);AMO=GAbiosynthesisinhibitorThe5-foldincreaseinGA1causesgrowthinspinachexposedtolongdaysExpressionofaL.temulentum20-oxidaseGAbiosynthesisgene.Comparedwithan8hshortday,LDexposureoftheleaf(8hSDextendedby9.5husingincandescentlamps)ledtoalargeincreaseingeneexpression.(Semi-quantitativeRTPCRassaysfromBlundell,MacMillan,andKing;unpublished).赤霉素生物合成的調(diào)控

——溫度的影響InSituHybridizationAnalysisof

AtGA3ox1

mRNA.(A)

Schematicdrawingofalongitudinalsection.ale,aleurone;cot,cotyledon;HY,hypocotyl;RA,radicle;SA,shootapicalmeristem;SC,seedcoat.(B)

Schematicdrawingofatransversesection.ale,aleurone;cor,cortex;cot,cotyldon;end,endodermis;epi,epidermis;PV,provasculature;SC,seedcoat.Biosynthesisandcatabolismofgibberellinarecarefullyregulatedduringthepromotionofseedgermination.

EffectsofGA3anduniconazolontheexpressionofOsGA3ox1andOsGA3ox2ingerminatingseeds.Lane1,control;lane2,10μMGA3;lane3,10μMuniconazole.GA3uniconazolecontrol赤霉素生物合成的調(diào)控

——反饋控制（Feedbackcontrol）赤霉素生物合成的調(diào)控

——反饋控制（Feedbackcontrol）赤霉素生物合成的控制—生長素的影響KNOXproteinsareexpressedintheSAM(purple),wheretheyactivate

CKbiosynthesisandrepressGA20-oxidasegeneexpression

andhenceGAbiosynthesis(GA20ox,gray),thuspromotingmeristem

activity.CKalsoactivatesGA2ox(blue)expression,possibly

stimulatingGAdeactivation.Theseinteractionsmayconfineactive

GAtotheleaf(green).KNOX

proteinsmayalsoactivateGA2oxin

aCK-independentmanner(dashedarrow).ModelDepictingInteractionsbetweenKNOXProteins,

GA,andCKintheShootApex赤霉素的代謝EUI降解赤霉素的途徑(Zhu&Nomuraetal.2006)(A)and(B)RicetransformedwithUbi:GA2ox5andUbi:GA2ox6.(C)to(F)TobaccotransformedwithUbi:GA2ox5andUbi:GA2ox6.Transgenicplantsshoweddifferentdegreesofdwarfismcomparedwiththecontrolriceortobaccotransformedwithvectoronly(MS).Photographsoftransgenictobaccoweretakenattheheadingstage([C]and[D])DwarfnesscanbegeneticallyengineeredThePlantCell,Vol.20:2603–2618,October2008,Wheatplants,cv,Canon,over-expressingaGA2-oxidasegene,whichencodesagibberellin-catabolisingenzyme,incomparisonwithwild-type(ontheleft).

Transgenicplantscarryinganantisenseconstructof3-hydroxylasehaveasemidwarfPhenotype.(a)InricethemajoractivegibberellininvolvedinshootelongationisGA1,whichisformedby3-hydroxylationofGA20

byGA3-oxidase(GA3ox).GA1

isturnedovertotheinactivecataboliteGA8

by2-hydroxylation,catalyzedbyGA2-oxidase(GA2ox).(b)PlantstransformedwiththesyntheticgeneOsGA3ox2:OsGA2ox1,inwhicharice2-oxidaseopenreadingframeisexpressedfromthepromoteroftheshoot-specific

OsGA3ox2

gene,havemoderateheightreductionandnormalgrainsizeandnumbers.Incontrast,plantstransformedwith

OsGA2ox1

expressedfromtheconstitutiveactinpromoterareseverelydwarfedandfailtosetgrain.NatureBiotechnology

21,873-874(2003)

Superdwarfrice：

未來的太空作物第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesis

andMetabolismPhysiologicalrolesMolecularmechanismApplication赤霉素的生理作用促進(jìn)莖節(jié)伸長生長Increaseenlongationofstemandleaves打破休眠，促進(jìn)種子萌發(fā)Breakdormancyandpromotegermination促進(jìn)開花Stimulateflowering促進(jìn)種子和果實(shí)發(fā)育Fruitformationandseeddevelopment赤霉素的生物測定法

—矮化水稻點(diǎn)滴法赤霉素促進(jìn)莖節(jié)伸長生長的機(jī)制赤霉素是通過增加細(xì)胞壁的伸展性來促進(jìn)細(xì)胞伸長生長，即赤霉素能夠增加木葡聚糖內(nèi)糖基轉(zhuǎn)移酶（xyloglucanendotransglycosylase，XET）活性，增加細(xì)胞壁的伸展性，同時也增加了細(xì)胞壁對擴(kuò)張蛋白的透性。赤霉素和生長素在促進(jìn)細(xì)胞伸長生長過程中是協(xié)同作用的關(guān)系，即赤霉素誘導(dǎo)XET酶的活性增加，改善了細(xì)胞壁對擴(kuò)張蛋白的透性，使大量的擴(kuò)張蛋白蛋白進(jìn)入細(xì)胞壁；生長素促進(jìn)質(zhì)子的分泌，酸化細(xì)胞壁環(huán)境，活化擴(kuò)張蛋白蛋白，使細(xì)胞壁的伸展性得到促進(jìn)。赤霉素首先誘導(dǎo)細(xì)胞的伸長生長，然后誘導(dǎo)細(xì)胞進(jìn)行分裂。也就是說，赤霉素通過細(xì)胞體積的擴(kuò)大，誘導(dǎo)G2期的分生細(xì)胞進(jìn)入M期，赤霉素誘導(dǎo)細(xì)胞分裂是赤霉素促進(jìn)細(xì)胞伸長生長的間接效應(yīng)。木葡聚糖轉(zhuǎn)葡糖苷酶(xyloglucanendotransglycosylase,XET)TrendsinPlantScience,1999.Vol.4,No.5,pp.176-183.

赤霉素誘導(dǎo)糊粉層細(xì)胞淀粉酶的合成和分泌赤霉素影響植物的發(fā)育狀態(tài)藍(lán)桉，灰楊柳Eucalyptusglobulus上：幼態(tài)；下：成熟態(tài)Injectingorchardtreewithgibberellintoincreaseconeproduction赤霉素促進(jìn)開花

Flowering第三節(jié)赤霉素GibberellinsDiscoveryChemicalstructureBiosynthesis

andMetabolismPhysiologicalrolesMolecularmechanismApplication山口五十磨GibberellinSignalingPhenotypesofwild-typeArabidopsisandgai,ga1,andthergamutantsgai=GA-insensitivega1=GA-deficientrga=repressorofga1RGAisanegativeregulatoroftheGAresponsergamutantslooklikewildtypeDomainstructureoftheRGAorGAIrepressorproteinDELLA=asparticacid(D),glutamicacid(E),leucine(L),leucine(L),alanine(A)onN-terminusofGAI,RGA,SCR=membersoftheGRASfamilyStructureoftheGA3–GID1A–DELLAComplexa,ChemicalstructuresandnumberingofGA3andGA4thatwereusedinourstudies.b,RibbonrepresentationoftheGA3–GID1A–DELLAcomplex,withtheGAIDELLAdomain(pink),theGID1AN-terminalextension(N-Ex,cyan)andtheGID1coredomain(lightblue).TheboundGA3moleculeisrepresentedasaspace-fillingmodelwithcarboningreenandoxygeninred.c,Asinb,butwitharotationof

90°aroundaverticalaxis.ThreeN-terminalextensionhelices

a–

cofGID1Aarelooselypackedagainsteachothertoformaflatcoveronthepocket.Gibberellin-inducedDELLArecognitionbythegibberellinreceptorGID1KohjiMurase,YoshinoriHirano,Tai-pingSun&ToshioHakoshimaNature456,459-463(27November2008)BoxedInBindingofgibberellin(grayspace-fillingstructure)withinitsreceptor(green)causesthereceptor'sN-terminus(purple)tocloseoverthehormonelikealid.ClosingthelidprovidesaplatformforbindinggenetranscriptionblockerscalledDELLA(blue).

AmodelofGA-regulatedGID1–DELLAproteininteractionsGAfunctionsasan'allostericinducer'toenhan