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Spotted-Leaf

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Spotted-Leafleaf,Leaf

    Spotted-Leaf

    RiceScience,2010,17(4):247.--256

    Copyright@2010.ChinaNationalRiceResearchInstitute.

    PublishedbyElsevierBv_Allrightsreserved

    DOI:101016/$1672-6308(09)60024x

    Spotted-LeafMutantsofRice(Oryzasativa)

    A,taitableOn"rIeatwww.sciencedirect.com

    ,

    

    SdenceDirect

    HUANGQi.nal,2,--,YANGYang,,SH!Yongfeng,CHENJie,WuJian-li

    (1StateKeyLaboratoryfcPBiology/Chhes8Nati~pnalCeterforfcPImprovement,ChinaNation,Rfi?eResearchInstJm,

    Hangzh~)"310006,China,"CollegeofL~feandEnvironmentalSciences,HangzhouNormalUniversity,Hangzhou310036,Chhm;

    Theseauthorscontributedequallytothispaper)

    Abstract:Manyricespotted--leafI(sp1)mutantsareidealsourcesforunderstandingthemechanismsinvolvedinblast

    resistance.,

    bacterialblightresistanceandprogrammedcelldeathinplants.Thegeneticcontrolsof50spotted_leafmutantsin

    dcehavebeencharactedzedandafewspotted1eafgeneshavebeenisolatedaswel1.Thisarticlereviewstheodgin,genetic

    modes,isolationandcharacterizationofspotted-4eargenesresponsiblefortheirphenotypes,andtheirresistanceresponses

    tomainricediseases

    Keywords:Oryzasativa;spotted-leaf;mutagenesis;diseaseresistance;programmedcellde

ath;gene

    Inheritablevariationsoccurrednaturallyorinduced artificiallyarefundamentaltoriceevolution.Riceplants

    mayformaseriesofvisibleorjinvisiblechanges. Amongthem,thespotted-.1eaf(sp0mutantsbelongto thevisible1eafheteromorphosisandshow1lesionsof differentcolors,shapesandsizesonleacsheath,panicle branchandhull(Wueta1.2008),.

    Thesplmutantsgeneratelesionsspontaneously withoutobviousstress,mechanicalwounding,pest damageorpathogeninfection.Inmanycases,the lesionsaresimilartothosecausedbvavirulent/ virulentpathogeninfection.Usuallylesionsarebrown, rangingfromreddishbrowntodarkbrown,andarc alikewiththericebrownspotandriceblastcausedby BipolarisoryzaeandMagnaportheoryzae,,respectively. Therefore,thesNmutantsareoftentermedlesion mimicorllesionsimulatingdiseasemutants(Dietrich etal,1994;Lorrainetal,2003).Insomecases,lesions arepurelyduetothecoloralteration(e.g.white) withoutcelldeathin/aroundthespots,whichareto~ly differentfromlesionscausedbypathogeninfection. Thus,itismoreprecisetoadapttheterm'spotted-leaf' recommendedbytheRiceGeneticsCooperative.In addition,,termsformanypreviouslyreportedmutants andgenesaremaintainediLnuse,similartothe situationforriceblast,forexample,brownleafspot (b1).Evenso,thenomenclatureformanynewly Received:22February2010;Accepted:26May2010 Correspondingauthor:WUJian--li(beishangd@163.corn)

    identifiedsplmutantsandtheircorrespondinggenes arestillinconsistentandunlikelytobeunifiedina shortperiodtimewithoutallelismtesL.

    Sourcesofricesplmutations

    Ithasbeenwellknownthatsplmut:ationscome fromspontaneousandartificialIinduction.Inl923. EmersonreportedamaizeNotchedmutantwhich couldbethefirstgeneticinvestigationofplantspl mutants.In1965.Sekiguchidiscoveredthefirst spontaneousricesplmutantthatwaslaternamed sekiguchilesion(sOandcontrolledbyasinglerecessive geneIiKiyosawa,1970).Forthepastfewyears,with theaccomplishmentofricegenomesequencingandthe developmentoffunctionalgenomics,.reportsonisolation andcharacterizationofricemutantshave]increased rapidly.Themajorityofthesemutantsweregenerated viaphysicalfe.g.gammaraysandneutron),.chemical [e.g.ethylmethanesulfonate(EMS)anddiepoxybutane (OEB)]andbiologicalmethods(e.g.T_DNA,transposon andretrotransposon)(Wuetal,2005;Bhatetal,2007). Inaddition.splmutantswerefrequentlyidentified duringtransgeneticstudiesdetailedinthereviewof

    MittlerandRizhsky(200o)].

    Bytheendof2009,morethan200000ricemutants havebeenobtainedandmaintainedinuniversitiesand researchinstitutionsworldwidebyphysica1.chemicalI andbiologicalinduction.MostmutationswereiLnthe 248

    backgroundofjaponicacultivarsNipponbareand Zhonghua11(Krishnanetal,2009).Moreimportantly,

    manymutantsarefreeofchargeandcouldbeshared inthescientificcommunitiesforresearchpurpose (Wuetal,2008).Uptonow,17sporedleafmutants

    (spi1tospillandblltobI6)havebeenregisteredand recordedbytheRiceGeneticsCooperative,andthe geneticcontrolsof50splmutantshavebeenclarified explicitly(Table1).

    Phenotypesofricesplmutants

    Themainphenotypeofricesplmutantsisthat theleafbladeorthesheathturnsuplesionswith differentcolors,sizesandshapes.Thebasiccolorof lesionsisbrown,sometimesreddishbrown(SpZ26), darkbrown(spll,orange(spl1)andwhite(spt2D) (Wuetal,2008).Becausethecolorofspotswas definedbynakedeye,thusdiscrepancytosome degreeindescriptionamongscholarsisinevitable. Theshapesoflesionscompriseofround,oval,rodand thread.Thes.

    izesofspotsvaryfromneedletiptolarge

    necrosis,butmostly210lxmindiameter.Inspiteof

    hugedifferenceofphenotypes,alllesionsaregenerated withoutpathogeninfection,mechanicalwounding,pest damageorstress.Similarlytorice,thespottedleaf

    mutationsarecommoninotherplantspeciessuchas Arabidopsis,maize,barleyandtobacco(Malamyetal, 1990;Dietrichetal,1994;Buschgesetal,1997;Moil etal,2007).Generally,therearetwogroupsofthespl mutants,i.e.initiationmutantsandpropagationor feedbackmutants.T}leinitiationmutantsformlocalized spotswithrelativelystablesize,forexample,6and

    MlO09(Araseetal,2000;Jungetal,2005).The propagationorfeedbackmutantsarenotabletocontrol therateandsizeofthespots,forinstance,splland lmml(Kiyosawa,1970;Wangetal,2006;Wangetal, 2007).Usually,thesplmutantsareknownas1esion mimicmutantsbecausethenatureofcellnecrosisis similartomatcausedbyhypersensitiveresponse(HR), atypeofprogrammedcelldeaths(PCD)inducedby pathogeninvasion(Walbotetal,1983).Timingof lesionemergencevariesaswellindifferentmutants. Mostly,lesionsappearattheearlyseedlingstageat2 t03weeksaftersowingg.spllspl2,spl3,spl4and spl9).ThericespottedleafmutantHM47derived

    RiceScience,Vo1.17,No.2010

    fromIR64byEMSmutagenesisexhibitedbrown lesionsonthefirstleafoneweekaftersowingand remainedthroughoutthewholelifecycle(unpublished data).LesionsofSp124andsp16-2appearedat4to6 weeksaftersowing,whereasthoseofHM95appeared latebeforeheading(Wuetal,2008;unpublisheddata). Environmentalfactorssuchastemperatureand lightaffectlesionformation.Forexample,thelesions ofricespl7emergedathightemperatureandunder solarirradiation,whereasOs/sd/generatedspotsat relativelylowtemperatureandundershortdaylength. Similarphenomenonhasbeenobservedfrequentlyin otherplantspecies(Hoisingtonetal,1982;Fuseetal, 1993;Dietrichetal,1994;Araseetal,2000;Grayetal, 2002;Liuetal,2003;Wangetal,2004)aswell, indicatingthatsplgenesmayparticipateinlight-or

    temperaturedependentmetabolicpathways,whichmay alsobeimportantforphotosynthesisandstresstolerance. Variationsofagronomictraitssuchasplantheight, fertility,tilleringandyieldinmanysplmutantsare oftenobservedsimultaneously.Ricesl,cdrlandspl5 aredwarf(Kiyosawa,1970;Takahashietal,1999;Yin etal,2000);spl3andSpl4arepartiallysterileand showadeclineofyieldproduction(Yinetal,2000); spll9isnarrowandcurl-?leavedwithlowseed--setting rate(Wuetal,2008);HM47ishighlydwarfandshows lowfertilityandreducednumberoffillers(unpublished data).Besides,somemutantsarelethalandcouldnot accomplishthewholelifecycle(Chenetal,2008), othersalehomozygouslylethalandshouldbemaintained asaheterozygote(Wuetal,2008).Thus,itisclear thatsplgenesdonotfunctionspecificallyandcould participateinawiderangeofphysiologicaland biochemicalprocessesresponsibleforplantgrowth, development,defense,senescenceanddeath. RicesplmutantsandHR

    Notallsplmutantsfornlnecroticlesions.but lesionmimicmutantsshowsymptomssimilartoHR withoutpathogeninfection.Celldeathinlesionmimic mutantsisbelievedtobeprogrammedeelldeathwhich playsanimportantroleinplantgrowthanddevelopment. Therefore,lesionmimicmutantshavebeenconsideredas oneoftheidealmaterialsforstudyingandacknowledging HUANGQi-na,eta1.SporedLeafMutantsofRice(Oryzasativa) Table1.Geneticmodesandcharacteristicsofspo~ed-leafmutantsinrice(OryzasaavaL?)?

    249

sp/2KatsumonbyoSponmneous

    sp/3Norin8 spl4Norin spl5Norin spl6Kinmaze spl7Norin8 spl8Kinmaze sp/9Norin8 spllO

    spill

    Sp112

    Sp113

    spll4

    Sp115

    spll6

    spll7

    Sp118

    spll9

    spl20

    spl21

    sp122

    sp123

    Sp124

    sp125

    126

    spt27

    sp128

    spl(t)

    bll

    b12

b13

    b14

    b15

    b16

    cdrl

    cdr2

    Cdr3

    ebr3

    ncrl

    M1009 trd32 Ird39 lrd40 lrd42 blm

    lmi

    lmml

    IR24

    IR68

    Hinohikari

    Hinohikari

    Taichung Koshihikari

    IR64

    IR64

    Nipponbare

    IR64

    IR64

    IR64

    IR64

IR64

    IR64

    IR64

    IR64

    IR64

    Hwacheongbye Zhejing22 Norin8

    Norin8

    Norin

    Norin

    Norin8

    Norin8

    Kinmaze

    Kinmaze

    Kinmaze

    CO39

    CO39

    Norin8

    Zhonghua1l Zhonghua11 Zhonghua11 Zhonghual1 Hwaeheong 3037

    Katy

    OslsdlNipponbare

    ttm1Nipponbare

    Yray

    Y'ray

Yray

    Methylnitrosourea 7.ray

    Methylnitrosourea 7'ray

    Methylnitrosourea Ethyl

    methanesulfonate Methylnitrosourea Methylnitrosourea Methylnitrosourea Methylnitrosourea Diepoxybutane

    Diepoxybutane

    T_DNA

    Diepoxybutane

    Fastneutron

    Diepoxybutane

    Diepoxybutane

    Diepoxybutane

    Diepoxybutane

    Diepoxybutane

    Diepoxybutane

    Diepoxybutane

    Methylnitrosourea Yray

    Spontaneous

    Spontaneous

    Spontaneous

    32P

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