Flowering and determinacy in Arabidopsis

Flowering and determinacy in Arabidopsis

Flowering and determinacy in Arabidopsis

JournalofExperimentalBotany,Vol.58,No.5,pp.899–907,2007

doi:10.1093/jxb/erm002AdvanceAccesspublication10February,2007

FLOWERINGNEWSLETTERREVIEW

FloweringanddeterminacyinArabidopsis

RobertSablowski*

CellandDevelopmentalBiology,JohnInnesCentre,NorwichNR47UH,UK

Received1November2006;Revised11December2006;Accepted5January2007

Abstract

newcellsataspeci cdevelopmentalstage.Inthesecases,Meristemsprovidenewcellstoproduceorgansthemeristemissaidtobedeterminate.Adeterminatethroughoutthelifeofaplant,andtheircontinuousmeristemproducesapartoftheplantbodywithapre-activitydependsonregulatorygenesthatbalancethedictablesizeandform,suchasthe ower,whereasin-proliferationofmeristemcellswiththeirrecruitmentdeterminatemeristemsproducepartsoftheplantwhosetoorganogenesis.During owerdevelopment,thissizeandshapedependonthelocalenvironment,suchbalanceisshiftedtowardsorganogenesis,causingasbranchesandrootsthatgrowtovariablelengths.Thethemeristemtoterminateafterproducingagenetic-positioningofdeterminateandindeterminatemeristemsallydeterminednumberoforgans.InArabidopsis,variesbetweenspeciesandisamajordeterminantofplantWUSCHEL(WUS)speci estheself-renewingcellsatarchitecture.

thecoreoftheshootmeristemsandisakeytargetinHere,thegeneticcontrolofmeristemdeterminacyinthecontrolofmeristemstability.ThedevelopmentofaArabidopsisandtheapplicabilityofthisknowledgetodeterminate oralmeristemisinitiatedbyAPETALA1/otherspeciesisreviewed.IntheArabidopsisshoot,CAULIFLOWER(AP1/CAL)andLEAFY(LFY).Thelatterdeterminacyisapropertyofthe oralmeristems,whereasactivatesAGAMOUS(AG),partlyinco-operationwiththevegetativeandin orescencemeristemsareindeter-WUS.AGthendirectsthedevelopmentoftheinner-minate.Theindeterminategrowthofthevegetativeandmost oralorgansandatthesametimeantagonizesin orescencemeristemsrequiresaspeci csetofregula-WUStoterminatethemeristem,althoughthemechan-torygenes,whoseactivityisantagonizedby ower-ismofWUSrepressionremainsunknown.Allthesespeci cregulators.Forthisreason,itisusefultostartgenesparticipateinaseriesofregulatoryfeedbackwithadescriptionofhowtheactivityofindeterminateloopsthatmaintainstableexpressionpatternsorpro-meristemsismaintained.

motesharpdevelopmentaltransitions.AlthoughtheregulatorsofmeristemmaintenanceanddeterminacyMaintenanceofindeterminatemeristems

inArabidopsisarewidelyconserved,theirinteractionsmayvaryinotherspecies.

Theindeterminategrowthofthevegetativeandin ores-cencemeristemsissustainedbysmallgroupsofself-Keywords:AGAMOUS,determinacy, owerdevelopment,renewingcellsthatarefunctionallysimilartostemcellsinshootmeristem,WUSCHEL.

animals(Sablowski,2004).Thesecellsarelocatedinthecentralzone(CZ)ofthemeristem,whilesomeoftheirdescendantsaredisplacedtotheperipheralzone(PZ),Introduction

wheretheyarerecruitedtoformneworganprimordia(Fig.1).BelowtheCZ,theribmeristem(RM)sustainsTheapicalmeristemsfunctionasthemainsourcesofnewstemgrowth.TheCZandPZfunctionshavebeenwellcellstosustainplantgrowth.TheregularrecruitmentofstudiedinArabidopsis,althoughtheRMhasreceivedmeristemcellstoformneworgansandtissuesisbalancedmuchlessattention.SuperimposedontheCZ/PZorgani-bycellproliferationwithinthemeristemtomaintainitszation,thetypicaltunica/corpusstructurefoundinsizerelativelystable.Thissteady-statecanpersistangiospermscanalsobedistinguished,withtwoexternalthroughoutthelifeoftheplant,butinmanycasesthelayers(L1andL2)inwhichmostcelldivisionsaremeristemisgeneticallyprogrammedtostopproducing

orientedtangentiallytothemeristemsurface,whilethe

*E-mail:Robert.sablowski@bbsrc.ac.uk

ªTheAuthor[2007].PublishedbyOxfordUniversityPress[onbehalfoftheSocietyforExperimentalBiology].Allrightsreserved.ForPermissions,pleasee-mail:journals.permissions@http://www.mianfeiwendang.com

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