《植物营养原理》课件 中量元素

第五章中量营养元素〔钙、镁、硫〕Section1CalciumandlimeFertilizerSection2MagnesiumandMagnesiumFertilizerSection3SulfurandSulfurFertilizerSection1Calcium1ContentandDistributionofCainPlants

2NutritionFunctionofCalcium3ResponseofPlantstoCaDeficiency4MolecularandphysiologicalaspectsofCalciumuptakeinplants1ContentandDistributionofCainPlants

0.1~5%ofdryweight.Dicotyledonous>Monocotyledon;Shoots>Roots;StemsandLeaves(older)>Fruit,Grains.Mostcalciumislocatedatcellwall,andafewatvacuole.

2NutritionFunctionofCalcium2.1CellWallStabilizationThereareanabundanceofbindingsitesforCa+inthecellwall.Inthestoragetissuesofapplefruits,thecellwall-boundfractionofCa+canmakeupasmuchas90%ofthetotal.CellwallMiddlelamellaPlasmamembraneCytoplasmVacuoleMitoch-ondrionCaCaCaMgCaCaMgCaB2.2CellExtension

IntheabsenceofanexogenousCa+supply,rootextensionceaseswithinafewhours.2.3MembraneStabilization

Calciumstabilizescellmembranesbybridgingphosphateandcarboxylategroupsofphospholipidsandprotein,preferentiallyatmembranesurfaces.

ThiscanbeanexchangeablebetweenCa+atthesebindingsitesandothercation(e.g.K+,Na+orH+),butcannotreplaceCa2+initsmembranestabilizationrole.钙对质膜稳定性的影响膜内膜内膜外膜外+Ca2+-Ca2+CaCaCaCaCaCaCaCaATPATPH+H+Na+K+H3O+Mg2+等Na+K+H3O+Mg2+等PlantcommunicationsaretransferredbythechangeofCa2+concentrationincytoplasm,WhichisrealizedbytheaffinityofCAMtoCa2+.

Calmodulin(钙调素，CAM)isalow-molecular-weightcompound(~20,000)whichbindsCa2+reversiblyandwithhighaffinityandselectivity.

2.4CommunicationTransduction

ActivatedCAMisrelatedtocelldivision,cellmovement,communicationtransferincell,photosynthesis,hormoneregulationandsoon.Calciumdeficiencysymptomcanbefirstobservedinthegrowingtipsandyoungesttissues.Thesebecomedeformedandchloroticandatamoreadvancedstagenecrosisoccursattheleafmargins.3ResponseofPlantstoCaDeficiency

Theaffectedtissuesbecomesoftduetoadissolutionofthecellwalls.Genotypicdifferenceexistsinresponsetocalciumsupply.Low-transpiringorganssuchasfleshyfruitswithhighgrowthrateeasilysufferscalciumdeficiency:tipburninlettuce,blackheartincelery,blossomendrot〔脐腐病〕intomatoorwatermelon,andbitterpit〔苦痘病〕inapple.

Lowtissuelevelsofcalciuminfleshlyfruitsalsoincreasethelossescausedbyenhancedsenescenceoftissueandbyfungalinfection.

番茄：脐腐病白菜干烧心甘蓝小麦：幼叶变形，失绿玉米Afailureoftheleaftipstoseparatefromthewhorl.

Thisisoftencalled"laddering".大豆番茄缺乏植株矮小，茎、根的生长点出现凋萎或坏死；幼叶变形，叶缘呈不规那么的锯齿状；叶尖相互粘边呈弯钩状，新叶抽出困难；早衰，结实少或不结实；常伴随铝、铁、锰的毒害。4MolecularandphysiologicalaspectsofCalciumuptakeinplants4MolecularandphysiologicalaspectsofCalciumuptakeinplants

CytosolicCaoccupiesaveryimportantpositioninplantcellsignaltransduction.PlantsignalswerethoughttobetransducedthroughCaincluding:touch,wind,temperatureshock,fungalelicitors,wounding,oxidativestress,redlight,bluelight,ABA,appliedelectricalfields,osmoticstresses,mineralnutritionandsoon.4.1CalciumsignalinginvolvesaseparationofdifferentconcentrationsofCa2+bymembranes,andthesignalsmustberegulatedbymolecularandphysiologicalaspectsofCalciumuptakeinplants

Ca2+signalingdependsonthetransmembraneelectrochemicalgradientsofacrosstheplasmmembraneandtheintracellularmembranes.Whencellsreceivesignals,Ca2+channelsaretransientlyopenedand[Ca2+]iincreasesrapidly.[Ca2+]isignalsaretruncatedbytheactivityofATPaseeslocatedintheplasmamembrane,thetonoplast,andERmembranes.ThesepumpsrestoreandmaintainlowconcentrationsofcytoplasmicCa2+.1胞外信号受体，2Ca2+-ATP酶，3原生质膜Ca2+通道IncreasesofcytosolicCa2+,activatecalmodulinwillinitiatesubsequentdownstreemevents.Duringsignaling,[Ca2+]cantransientlyreachveryhighconcentrations,especiallynearthemouthsofopenchannels.Openedabouttwomilliseconds,redisthehighest.Severaltransportmechanismsactivatedbyhigh[Ca2+]i4.2MechanismexistforsensingthestateofintracellularstoresofCa2+andreplenishingthemasneededRedlightinduceschangesintheconcentrationofcytosolicCa2+andthevolumeofyellowedwheatleafprotoplastsAsingleopenCa2channelcanconductanestimated106ionspersecond.Continuoussignalingcanrapidlyexhaustintracellularstores,whichmustthenberefilledbeforesignaltransductionorsensingcancontinue.Redlight-inducedchangesincytosolicCa2+insinglewheatleafprotoplastsloadedwithCa2+–sensitivefluorescentdye.4.3Calciumtransportsystem原生质游离Ca2+浓度的变化是通过两个方向相反的Ca2+流动系统：

I通过Ca2+通道(Ca2+channel)的流入(Ca2+influxsystem)系统

II，通过Ca2+转运子(Ca2+transporter)的流出(Ca2+effluxsystem)系统植物细胞内由3种类型的Ca2+通道，包括电压门控室Ca2+通道〔voltage-gatedCa2+channel〕接收体和第二信使调节式(receptorandsecondmessenger-regulatedCa2+channel)延伸式Ca2+通道(stretchchannel)。4.3.1CalciumChannel电压门控式Ca2+通道〔voltage-gatedCa2+channel〕电压门控式Ca2+通道存在于原生质膜和液泡膜上。在原生质膜上的Ca2+通道还表现出较宽范围的Ca2+/K+选择性〔Ca2+/K+为2:1~20:1〕存在于原生质膜和液泡膜。OsTPC1：encodingaputativevoltage-gatedCa2+channelfromrice,expressedinmatureleaves,shootsandrootsaswellasinculturedcells.PlantCellPhysiol.45(6):693–702(2004)4.3.1CalciumChannel接收体和第二信使调节式(receptorandsecondmessenger-regulatedCa2+channel)

接收体和第二信使调节式Ca2+通道存在于液泡膜、内质网膜和核膜上。这类通道的开闭主要通过与3-磷酸肌醇（inositoltriphosphate,IP3）或ADP-核糖作用来调节的。而且，ADP-核糖的合成是受ABA调控的。1，4，5－三磷酸肌醇(IP3)的受体位于液泡膜和内质网膜。该受体通过改变构像来传递信息。

离子通道受体由4个亚基组成，与IP3结合时，构像改变导致2个亚基的移动。正负电荷的分布通道的稳定，使Ca2+进入细胞质。4.3.1CalciumChannel延伸式Ca2+通道(stretchchannel)延伸式Ca2+通道存在于原生质膜和液泡膜上，通过感受膜的张力变化来控制通道的开闭。因此，机械类信号〔如触摸、风等〕通过调节原生质膜和细胞壁之间的互作关系改变膜张力，而干旱那么是通过调节细胞膨压增强原生质膜与细胞壁之间的压力来启动延伸式Ca2+通道。4.3.2Calciumtransporter目前所发现的Ca2+转运子为拟南芥液泡膜上的H+/Ca2+反向转运子〔H+/Ca2+antiporter〕，CAX1、CAX2和CAX3。H+/Ca2+反向转运子由大约400个氨基酸组成，具有10～14个跨膜域，其主要功能是维持细胞原生质膜保持较低的Ca2+浓度。植物中广泛的代谢和发育信号都可以引发胞质中游离Ca2+

的提高。游离Ca2+

提高的直接作用目标包括离子通道，转运子，还包括钙调蛋白、含有钙调蛋白域的蛋白激酶等。TherateatwhichfreeCa2+diffusesinthecytoplasmismuchslowerthanthatinfreesolution(atleasttwoordersofmagnitude).Thelowrateofdiffusionisanimportantpartof[Ca2+]isignaling.PollentubesmaintainastandinggradientofcytosolicCa2+intheirtipregion.Itisthebaseforpollentubegrowth.Signalingthrough[Ca2+]imayinvolvewaves,oscillations,capacitativecalciumentry,andpacemakercellsoscillationsin[Ca2+]iaccompanypollentubegrowth(B)WhichresultsfromthealternationoftheactivitiesofchannelsandATPases.pollentubegrowth(A)Theoscillationsofgrowingpollentube钙的波动在1分钟时间到达花粉管顶部(B)钙波发生的可能机制ThedurationofatransientinfluxofCa2+determinesthedistancethataCa2+signalpenetratesfromtheplasmamembranetothecytoplasmabecausediffusesslowlyincytoplasm.CalmodulinistheprimarycalciumreceptorCalmodulin:15~17kDa,150aa,4Ca2+bindingregions.OnbindingCa2+,calmodulinundergoesasubstantialchangeintertiarystructure.Suggestedconstituentsforatransducon,acomplexofproteinsthatactstotransducesignals.单个基因表达与特异表型之间的直线关系。基因表达与环境因子之间复杂的信号传导网络。许多信号改变了膜电位并激活了电压门通道，允许Ca2+进入细胞质。并进一步激活翻开K+和Cl-通道。可能的ABA传导途径从磷酸脂酶C〔PLC〕的激活到细胞质钙增加的传导顺序。SomeoftheknowninteractionsintheplantcellsignaltransductionnetworkPNAS,2007,104,3639-3644Plantscansenseandrespondtomechanicalstimuli,likeanimals.TobegovernedbyanunidentifiedsensorycomplexescontainingaCa2+-permeable,stretch-activated(SA)channel.

Aplasmamembraneprotein(Mca1)thatcorrelatesCa2+influxwithmechanosensing.Mca1mediatedCa2+influx,alsoincreased[Ca2+]cytuponplasmamembranedistortioninArabidopsis.ThegrowthofMCA1-overexpressingplantswasimpairedinahigh-calciumbutnotalow-calciummedium.Theprimaryrootsofmca1-nullplantsfailedtopenetrateaharderagarmediumfromasofterone.TheseobservationsdemonstratethatMca1playsacrucialroleinaCa2+-permeableSAchannelsystemthatleadstomechanosensinginArabidopsis.Yukoetal.,PNAS,2007,104,3639-3644RT-PCRNorthernblotting

OverexpressionofMca1increasesCa2+uptakeinintactroots.Theuptakeisinhibitedby1mMGd3+,butnotby20µMverapamil(异搏定).

Hypoosmoticshock-induced[Ca2+]cytchangesSummaryofhypoosmoticshock-andTNP-induced[Ca2+]cytchanges.EffectofchannelblockersandaCa2+

chelatoronthehypoosmoticshock-induced[Ca2+]cytincrease.Stretch-activatedCa2+responseinMCA1-expressingandmock-transfectedCHOcells.(A)AseedlingoftheMCA1oxlineS3,showingbrowningofthehypocotyl.(B)AnMCA1oxplant(lineS1),showingaphenotypewithnopetals,shrunkensiliques,shortstems,andsmallrosettes.(C)Ca2+-dependentgrowthphenotypesofMCA1oxseedlings.NotethattheordinaryMSmediumcontains3.0mMCaCl2.Onthismedium,MCA1oxseedlingsexhibitedgrowthdeficiency.(D)Failuretopenetratethelower,harderagar(1.6%)mediumPhenotypesofmca1-nullandMCA1oxlines.Ca2+-dependentproteinkinases(CDPKs)playanessentialroleinplantCa2+-mediatedsignaltransduction.Twenty-nineCDPKgenesinricegenome(OsCPK1-29)11oftheCDPKgenesareregulatedbychillingtemperature,dehydration,salt,riceblastinfection.OsCPK6,OsCPK13,OsCPK17andOsCPK25wereinducedbychillingtemperature,dehydrationandsaltstressesinthericeseedlings.Wanetal.,FEBSLetters581(2007)1179–1189OsCPK6isup-regulatedbydrought;(B)OsCPK25isinducedby45℃heattreatment;

(C)OsCPK17isdown-regulatedbycold,droughtandsaltstimuli.Section2Magnesium1ContentandDistributionofMginPlants

2NutritionFunctionofmagnesium3ResponseofPlantstoMgDeficiency4MolecularandphysiologicalaspectsofMagnesiumuptakeinplants1ContentandDistributionofMginPlantsContentinplants:0.05~0.7%Legumes>Cereals(2~3times)

Distribution:

Seed>stem,leaf>root2NutritionFunctionofmagnesium2.1ChlorophyllSynthesisandCellularpHControl

AmajorfunctionofMg2+isitsroleasthecentralatomofthechlorophyllmolecule.

2.2ProteinSynthesis

Mgalsohasanessentialfunctionasabridgingelementfortheaggregationofribosomesubunits,aprocessthatisnecessaryforproteinsynthesis.

MgisalsorequiredforpolymerasesandhencefortheformationofRNAinthenucleus.

Synthesos

(μg/mlsuspension)810200162481624050100MgAMgMgMgMgMgTime(h)BEffectofmagnesiumon(A)RNAand(B)proteinsynthesisinchlorellapyrenoidosasuspensionculture(BasedonGalling,1963.)

Inleafcellsatleast25%ofthetotalproteinislocalizedinchloroplasts.WhichexplainswhyadeficiencyofMgparticularlyaffectsthesize,structure,andfunctionofchloroplast.LowerchlorophyllcontentsinMg-deficiencyleavesarecausedbyinhibitedproteinsynthesisratherthanalackofMg2+.

2.3EnzymeActivationandEnergyTransferThereisalonglistofenzymereactionswhichrequireorarepromotedbyMg2+:

phosphatasesandATPase;RuBPcarboxylase;fructose-1,6-diphosphatase

ThesubstrateformostATPases3ResponseofPlantstoMgDeficiency缺乏症在中下部叶片有较明显的病症叶色褪淡，脉间失绿，呈清晰的绿色网状脉纹单子叶植物叶脉上有间断串珠状绿色斑块，双子叶植物叶片上有紫红色斑块。油菜：叶脉失绿，叶片变黄，有褐色斑点烟草菜豆番茄甘蓝花椰菜萝卜茄子1ContentandDistributionofsulfurinPlants

2Assimilationofsulfur3NutritionFunctionofsulfur4ResponseofPlantstoSulfurDeficiency5MolecularandphysiologicalaspectsofSulfuruptakeinplantsSection3Sulfur1ContentandDistributionofsulfurinPlantsContent:0.1~0.5%Cruciferaes>legume>cerealDistribution:majorlocatedinleavesbeforeflowering;transfertootherorgansaftermature.Twomajorformsofsulfurinplants:inorganicandorganic:

Inorganic:SO42-;

Organic:sulfur-containingaminoacid.Sulfurtakenbyplantsfirstsatisfiesthedemandoforganicsulfursynthesis.Superfluoussulfurisstoredatvacuole.3NutritionFunctionofsulfur3.1proteinsynthesisSisaconstituentofcysteineandmethionineandhenceofproteins.Sisastructuralconstituentofthesecompound(R1-C-S-C-R2)oractsasafunctionalgroup(R-SH)directlyinvolvedinmetabolicreactions.Theformationofadisulfidebondbetweentwoadjacentcysteineresiduesinpolypeptidechainsisoffundamentalimportanceforthetertiarystructure.

Thedisulfidebondmayformapermanent(covalent)cross-linkbetweenpolypeptidechainsorareversibledipeptidebridge.Studyingitwillbeusefultoprovidecellularresistancetodehydration(causedbydroughtandheat)andfrostdamage.3.2TransferElectron

R1-SH+HS-R2R1-C-S-C-R2-2H++2H+硫氧还蛋白的复原与蛋白质二硫键的氧化示意图SHSHSS蛋白质二硫键还原作用PS2P（SH）2NADP+或FdoxNADPH+H+或Fdred硫氧还蛋白还原酶4ResponseofPlantstoSulfurDeficiencyInhibitionofproteinsynthesisduringsulfurdeficiencyleadstochlorosis,justasitdoesduringNdeficiency.UnlikeN,however,Sdeficiencysymptomoccursfirstinyounger,mostrecentlyformedleaves:alightgreenoralightyelloworyellow,andplantsarerigid,brittleandthestemsremainthin.缺乏植株发僵，新叶失绿黄化双子叶植物较老的叶片出现紫红色斑块开花和成熟期推迟，结实率低，籽粒不饱满。大豆油菜：花小色淡菜豆：新叶开始黄化番茄芹菜Sulfurdeficiencyonalfalfaisexhibitedassmall,lightgreenplants.未施硫油菜施硫油菜Loavesofbreadba