(B)Active CDK(A)Mitoticphasestimulatesmitosis1-eserMcyclinedegradationPP淘OCDKOMitosisInactiveMG2CDKInactiveMGCDKCDKDKPPATPSQADPADPINTERPHASEMitotic2ATPEcyclin (CM)6(A)Diagramofthecell cycle.(B)FIGURE1.26Diagramoftheregulation ofthecell cyclebyCDKG,cyclin (Cg.)InactiveCDKcyclin-dependentproteinkinase (CDK).DuringG,CDKisinitsinactiveform.CDKbecomesactivatedbybindingtoGcyclin(Cc)and byCDKbeing phosphorylated (P)at theactivation site.The activatedP?CDK-cyclincomplexallowsthetransitiontotheSphase,AtActivationInhibitorythe end of the Sphase,the G, syclin is degraded and theOsitesiteCDK is dephosphorylated, resulting in aninactive CDKGCyclindegradationThecellentersG.DuringGa,theinactiveCDKbindstotheActiveCDKmitotic cyclin (CM),orM cyclin.Atthe same time,thestimulatesDNACDK-cyclincomplexbecomesphosphorylatedatbothitssynthesisactivationand itsinhibitorysites.The CDK-cyclin complexis still inactivebecausetheinhibitorysiteis phosphorylated,Theinactivecomplexbecomes activated whenthephosphateis removed fromtheinhibitorysitebya proteinphosphatase.Theactivated CDK then stimulates thetransi-tionfromG,tomitosis.Attheend ofmitosis,themitoticFigure 10-2cyclin is degraded and the remaining phosphate at the acti-vation site is removed by thephosphatase, and the cellentersG,again
Figure 10-2
cell wallcellulosefibril200nmmicrofibrilplantcellFigure 10-5OHOHOHOHCC2OHOHOHOHOHOH8cellulosemicrofibrilOHOHOHOHhydrogenbondOHOHOHOHOOHOHOHOHCellulose fibrils.Inplantcell walls,eachcellulosefibril containsseveralmicrofibrils.Eachmicrofibril containsmanypolymersofglucosehydrogen-bondedtogether.Threesuchpolymersareshown
Figure 10-5
H+H+H+IAA+.H+ABP1H+ATPATPATPATPIAAATPActivationABP1hypothesisIAAATP+H+SecondRoughERGolgi bodymessengersNUCLEUSATP6+H+Proteinprocessing鞋PromoterH+-ATPasegeneATPH+mRNASynthesishypothesisH+-ATPase?invesiclemembranePlasmaH+ActivationCELL WALLmembraneExpansinFIGURE19.25Current models for IAA-induced Ht extrusion. In many plants,bothof these mechanisms may operate.Regardless of how Htpumping is increased,acid-induced wall loosening is thoughtto be mediated by expansins.Figure 10-6
Figure 10-6
IAAconcentration(mg/ml)0.030.181.083.00.00.0050.0e0.21.0FiGuRE21.13Theregulationof growthand organformation incultured tobacco callusatdifferentconcentrations of auixin andkinetin.Atlow auxinand high kinetin concentrations (lower left)buds developed.Athigh auxin and low kinetin concentrations(upperright)rootsdevelopedAtintermediateorhighconcentrations ofbothhormones (middle and lowerright)undifferentiatedcallusdeveloped.(CourtesyofDonaldArmstrong.)Figure 10-7
Figure 10-7
1大抱子形成3、胚乳，糊粉层（单子叶植物）2柄退化毛状体发育4、aH7、叶衰老9、过敏反应（抗病）8通气组织形成5、管状分子形成6.根冠aFig.10-8
Fig.10-8
trackinglightcurvingofstemFigure 10-11-0Phototropism,Time-lapsephotograph ofa buttercup,Ranunculus ficaria, curving toward and tracking a source of light
Figure 10-11-0
Divided agar blockUndividedagarblock(A) Dark(C)Corn coleoptiletipexcisedandplacedColeoptile tipcompletelydividedonagarbythin pieceofmica;Agarblockno redistribution25.811.511.2ofauxinobservedCurvatureangle(degrees)(B)Unilateral light(D)Coleoptile tippartlydividedbythin pieceofmica;lateralredistribution ofNodestruction of auxin25.68.115.4auxinoccurs.Auxin is transported laterallytotheUnilateral light does not cause theshaded side in thetipphotodestructionof auxin on theilluminated sideFIGURE19.27Evidence that thelateral redistribution of auxin is stimulated by unidirectional light in corn coleoptiles.Figure 10-11
Figure 10-11
6aGravitropism.a.NegativegravitropismofthestemofaColeusplant24hoursaftertheplantwasplacedonits side.b.Positivegravitropismofagravirootemergingfromacornkernel.c.Sedimentationofstatoliths(seearrows),whichareamyloplastscontainingstarchgranules,isthoughttoexplainhowrootsperceivegravityFigure 10-1225.μm
Figure 10-12
FIGURE19.33Proposedmodelforthe(A)Verticalorientation1.IAAissynthesizedredistribution of auxin during gravitrointheshoot andpisminmaizeroots.(AfterHasensteintransported totheandEvans1988.)rootinthestele.CortexElongationSerezorte(flavonoidAsynthesis)2.Whenthe root isvertical, thestatoliths in the capsettletothebasal ends ofthecells.AuxinRootcaptransportedacropetallyintherootvia the stele is distributed equallyonTAAIAAall sidesoftherootcap.TheIAAis4IAAthentransported basipetallywithinRootcap cell2a99thecortextotheelongationzone,(enlarged)whereitregulatescellelongation.Statoliths(B)Horizontalorientation6.Thedecreasedauxinconcentration ontheFigure 10-14IAAuppersidestimulatestheupperside togrow.As a result, theIAArootbendsdown.SIAAIAA5.Thehigh.concentration4.Themajorityof the3.Inahorizontal rootofauxinonthelowerauxininthecapisthestatolithssettletoside of the root inhibitsthentransportedthe side ofthe capgrowth.basipetallyinthecells,triggeringpolarcortexonthelowertransport ofIAAtotheside of the root.lowersideofthecap
Figure 10-14
Cellwall细胞壁Plasmamembrane细胞膜造粉体AmyloplastAuxinC生长素无活性的钙调素CaMunactivity3已被激活的钙调素CaMactivated4a4b5ER内质网s0eCPFCPCa生长素泵IAA-pump-pump钙泵5a.IFig.10-15
Fig.10-15