Enhanced heat and drought tolerance in transgenic rice seedl

WRKY REPORT

PlantCellRep(2009)28:21–30DOI10.1007/s00299-008-0614-x

GENETICTRANSFORMATIONANDHYBRIDIZATION

EnhancedheatanddroughttoleranceintransgenicriceseedlingsoverexpressingOsWRKY11underthecontrolofHSP101promoter

XiaolanWuÆYokoShirotoÆSachieKishitaniÆYukihiroItoÆKinyaToriyama

Received:18June2008/Revised:28August2008/Accepted:9September2008/Publishedonline:26September2008ÓSpringer-Verlag2008

AbstractAnOsWRKY11gene,whichencodesatran-scriptionfactorwiththeWRKYdomain,wasidenti edasoneofthegenesthatwasinducedbybothheatshockanddroughtstressesinseedlingsofrice(OryzasativaL.).TodetermineifoverexpressionofOsWRKY11confersheatanddroughttolerance,OsWRKY11cDNAwasfusedtothepromoterofHSP101ofriceandintroducedintoaricecultivarSasanishiki.OverexpressionofOsWRKY11wasinducedbyheattreatment.Afterheatpretreatment,thetransgeniclinesshowedsigni cantheatanddroughttol-erance,asindicatedbytheslowerleaf-wiltingandless-impairedsurvivalrateofgreenpartsofplants.Theyalsoshowedsigni cantdesiccationtolerance,asindicatedbytheslowerwaterlossindetachedleaves.Ourresultsindi-catethattheOsWRKY11geneplaysaroleinheatanddroughtstressresponseandtolerance,andmightbeusefulforimprovementofstresstolerance.

KeywordsDroughttoleranceÁHeattoleranceÁTransgenicriceÁWRKY

Introduction

Droughtstresshasbeenfoundtobeoneofthemajorcausesofreducedcropyield(Ozturketal.2002),andgreateffortshavebeenmadetobreeddrought-tolerantcropvarieties.Asthemostimportantworldfoodcrop,culti-vatedrice(OryzasativaL.)demandstremendousamountsofwaterduringgrowth,whichresultsinanumberofproductionchallenges.Riceisalsoapopularmodelplantforstudiesofmonocots.Improvementsinthetoleranceofcerealplantstoabioticstressareimportantwhentheef -ciencyoffoodproductionistobeincreased.Breedingoftransgenicricecultivarwithdroughttolerancecanhelpincreaseandstabilizecropyieldunderstressenvironments.Manytransgenicapproacheshavebeencarriedouttoincreasebioticandabioticstresstolerance(seeBajajandMohanty2005forareview).Onesuccessfulapproachtoincreaseabioticstresstoleranceisoverexpressionofcertainstress-inducibletranscriptionfactors,suchasthefollowing:CBF1/DREB1B,CBF2/DREB1C,CBF3/DREB1A(Thomashow1999);DREB1A(Kasugaetal.1999);DREB2A(Sakumaetal.2006);EmBP1,OSBZ8,TAF1(Zhu2002);SNAC1(Huetal.2006).However,employmentofaconstitutivepromotersuchasCaMV35Stodrivegenesfortranscriptionfactorsmaypresentsomeriskofdeleteriouseffectonplantgrowth(Romeroetal.1997;Kasugaetal.1999).OverexpressionoftheOs-DREB1Aproteinshasbeenreportedtocausegrowthretardationunderunstressedcontrolconditionsintrans-genicriceplants(Itoetal.2006).SimilarphenomenaconcerningimprovementofstresstoleranceandgrowthretardationhavebeenobservedintransgenicArabidopsisoverexpressingCBF1/DREB1B,CBF2/DREB1C,orCBF3/DREB1A(Thomashow1999;Kasugaetal.1999)andintobacco(Kasugaetal.2004).Ithasbeenreported

CommunicatedbyH.Ebinuma.

X.WuÁY.ShirotoÁY.ItoÁK.Toriyama(&)LaboratoryofEnvironmentalBiotechnology,

GraduateSchoolofAgriculturalScience,TohokuUniversity,1-1Tsutumidori-Amamiyamachi,Aoba-ku,Sendai981-8555,Japan

e-mail:torikin@bios.tohoku.ac.jp

S.Kishitani

LaboratoryofPlantBreedingandGenetics,GraduateSchoolofAgriculturalScience,

TohokuUniversity,1-1Tsutumidori-Amamiyamachi,Aoba-ku,Sendai981-8555,Japan

123

WRKY REPORT

22thatthestress-induciblerd29Apromoterinsteadoftheconstitutivepromoterminimizesthisnegativeeffectonplantgrowth(Kasugaetal.1999,2004).Itis,therefore,desirabletousestress-induciblepromoterstoproducestresstolerantplants.

Tosearchfordroughtandheat-inducibletranscriptionfactorsinrice,wepreviouslyfocusedonriceorthologsofArabidopsisgenesfortranscriptionfactorsknowntobeinducedbydroughtorheat(Sekietal.2002;Oonoetal.2003;Rizhskyetal.2004).Usinghydroponicallygrownseedlings,OsWRKY11(DDBJaccessionno.AK108745;previousnamewasWRKY16inaccessionno.AY341856)wasidenti edtoshowenhancedexpressionbyplacingtheplantsat38°Cfor1h(heattreatment),byleavingtheplantsoutofwaterfor10h(droughttreatment)andbycombinedheat/droughttreatmentfor0.5h(Shirotoetal.2004).

TheWRKYgenesencodealargegroupoftranscriptionfactors.Thereareover70WRKYgenesinArabidopsisandover100membersinrice(Wuetal.2005;ZhangandWang2005;Liuetal.2007;Ramamoorthyetal2008).Thisfamilyisde nedbyadomainof60aminoacidscontainingtheaminoacidsequenceWRKYatitsamino-terminalendandaputativezinc ngermotifatitscarboxy-terminalend.Itbindsspeci callytotheDNAsequencemotif(T)(T)TGAC(C/T),whichisknownastheWbox.WRKYgenesareknowntoparticipateinvariousdevelop-mentalandphysiologicalprograms,includingdiseaseresistance(ChenandChen2000;Dellagietal.2000;DuandChen2000;Eulgemetal.2000;Kimetal.2000;Asaietal.2002),senescence(HinderhoferandZentgraf2001;RobatzekandSomssich2001),bioticandabioticstressresponses(Yodaetal.2002;Dongetal.2003;HuangandDuman2002;Haraetal.2000;Rizhskyetal.2002,2004;Pnuelietal.2002;Sekietal.2002),andgrowthand

developmentalprocesses(Lagace

´andMatton2004;John-sonetal.2002;Sunetal.2003;Xuetal.2004).Tothebestofourknowledge,however,noinformationisavailableregardingtherelationshipbetweenoverexpressionofWRKYgenesandheatanddroughttolerance.

TodetermineifoverexpressionofOsWRKY11confersheatanddroughttolerance,OsWRKY11cDNAwasfusedtothepromoterofHSP101ofriceandintroducedintorice.ThepromoterofHSP101wasemployedinthisstudy,becausetheHSP101genehasbeenreportedtobeinducedbyheatshock(Agarwaletal.2003).Althoughthepro-moteractivityofHSP101hasnotbeenreported,itwasexpectedthatthepromoterwasstress-inducibleandcouldbeusedtominimizepossibledeleteriouseffectsofOs-WRKY11expressionunderunstressedconditions.Inthisstudy,we rstexaminedactivationofHSP101promoterbyheatanddroughtstress,andthephenotypeoftransgenicplantsoverexpressingOsWRKY11.Then,weevaluated

123

PlantCellRep(2009)28:21–30

survivalofgreenpartsofplantsafterheatanddroughttreatment,andwaterlossofdetachedaerialpartsduringdesiccation.Enhancedheatanddroug …… 此处隐藏：36304字，全部文档内容请下载后查看。喜欢就下载吧 ……