Regulation-of-OsSPL14-by-OsmiR156-defines-ideal-pl

NatureGeNetics Increasing crop yield is a major challenge for modern agriculture. The development of new plant types, which is known as ideal plant architecture (IPA), has been proposed as a means to enhance rice yield potential over that of existing high-yield varieties,2. Here, we report the cloning and characterization of a semidominant quantitative trait locus, IPA1 (IdealPlantArchitecture1), which profoundly changes rice plant architecture and substantially enhances rice grain yield. The IPA1 quantitative trait locus encodes OsSPL4 (SOUAMOSA PROMOTER BINDING PROTEIN-LIKE 4) and is regulated by microRNA (miRNA) OsmiR56 invivo. We demonstrate that a point mutation in OsSPL14 perturbs OsmiR56-directed regulation of OsSPL14, generating an ‘ideal’ rice plant with a reduced tiller number, increased lodging resistance and enhanced grain yield. Our study suggests that OsSPL14 may help improve rice grain yield by facilitating the breeding of new elite rice varieties.Riceplantarchitectureiscrucialforgrainyieldandisdeterminedbyplantheight,tillernumberandangle,andpaniclemorphology.Theimportantcharacteristicsoftheidealplantarchitecture(IPA)includelowtillernumberswithfewunproductivetillers,moregrainsperpaniclethanthecurrentlycultivatedvarieties,andthickandsturdystems1,2.However,themolecularmechanismsforgeneratingtheIPAandincreasingyieldpotentialremaintobeelucidated,andgenesapplicableforimprovingriceplantarchitectureareverylimited.Differentricevarietieshavedistinctplantarchitectureandthereforedistinctyieldpotential.Incomparisontocurrentlycultivatedricevarieties,includingtheindicavarietyTaichungNative1(TN1),thejaponicalineShaoniejing(SNJ)hasplantarchitecturethatexempli-fiestheconceptofIPA,includingplantheight,tillernumberandpaniclemorphology(Fig.1a).BackcrossingSNJwithTN1orHui7(ajaponicaline)showsthatplantheight,tillernumberandpaniclemorphologydonotsegregateinthebackcrossprogenies,implyingthatthedifferencesinplantarchitecturebetweenTN1orHui7andSNJmaybecontrolledbyasinglelocus.WethereforedesignatedthelocusthatdeterminestheSNJarchitectureasIPA1.GeneticanalysisindicatedthatIPA1wassemidominant,giventhatthephenotypeofheterozygousplants(OsSPL14IPA1/ipa1)wasintermediatebetweenthoseofthehomozygousplantsOsSPL14IPA1/IPA1andOsSPL14ipa1/ipa1(SupplementaryFig.1).Fortheconvenienceofscoringthephenotype,wechosetillernumberasthetraittouseinmappingtheIPA1locus.Using110BC2F2plantlinesgeneratedfromthebackcrossbetweenSNJandTN1,wedetectedthelargest-effectquantitativetraitlocus(QTL),whichexplained29.9%oftillernumbervariance,atqTn8.qTn8wasmappedtothelongarmofchromosome8betweenmarkersRM149andRM1345(Fig.1b,c),whichismostlikelythesamelocusasthatofapreviouslyreportedQTLthatdefinesricetillernumber3,4.ToclonethegeneunderlyingtheIPA1locus,5,500BC2F2plantsthathadsimi-lartillernumberstoTN1wereidentifiedandgenotypedwithnewlydevelopedmolecularmarkers(SupplementaryTable1).WenarrowedthecandidateregioncontainingtheIPA1locusto~78kbbetweenmarkersM4andM5(Fig.1d),whichcontains12pre-dictedgenesorORFs(Fig.1eandSupplementaryTable2;seeURLs).Sequencingofthe12genesinSNJshowedonlyonepointmutationinthethirdexonofOsSPL14(LOC_Os08g39890;RAPIDOs08g0509600)comparedtotheNipponbarevarietyofrice.Thisnucleotidesubstitu-tionleadstoanaminoacidchangefromleucinetoisoleucineinSNJplants(Fig.1fandSupplementaryFig.2).Inaddition,Ri22,ajaponicalineshowingsimilarplantarchitecturetoSNJ,wasalsofoundtoharboranidenticalmutationinOsSPL14,whereasnomutationatthislocuscouldbedetectedinthericevarietiesTN1,93-11orZhonghua11.WefoundthattheexpressionlevelofOsSPL14wasaffectedbythepointmutation(SupplementaryFig.3).TodeterminewhetherOsSPL14underliestheIPA1QTL,weperformedaconfirmationtestbygeneratingtransgenicplantsexpress-ingdifferentlevelsofOsSPL14intheNipponbareandRi22lines,thejaponicavarietiessuitableforgenetransformation.WeintroducedtheplasmidcarryingOsSPL14(designatedgOsSPL14),whichcon-taineda7.2-kbgenomicDNAfragment,intoNipponbare(seeOnlineMethods).ThegOsSPL14transgeniclineshadreducedtillers,strongerculmsandincreasedpaniclebranchesandgrainyield(SupplementaryFig.4).Incontrast,theOsSPL14RNAinterference(RNAi)transgenicplantsintheRi22backgroundgeneratedmoretillersandshowedamarkedreductioninplantheight,diameterofculms,paniclebranchesRegulationofOsSPL14byOsmiR156definesidealplantarchitectureinriceYongqingJiao1,4,YonghongWang1,4,DaweiXue2–4,JingWang1,MeixianYan2,GuifuLiu1,GuojunDong2,DaliZeng2,ZefuLu1,XudongZhu2,QianQian2&JiayangLi11StateKeyLaboratoryofPlantGenomicsandNationalCenterforPlantGeneResearch,InstituteofGeneticsandDevelopmentalBiology,ChineseAcademyofSciences,Beijing,China.2StateKeyLaboratoryofRiceBiology,ChinaNationalRiceResearchInstitute,ChineseAcademyofAgriculturalSciences,Hangzhou,China.3Presentaddress:CollegeofLifeandEnvironmentSciences,HangzhouNormalUniversity,Hangzhou,China.4Theseauthorscontributedequallytothiswork.CorrespondenceshouldbeaddressedtoJ.L.([e-mail])orQ.Q.([e-mail]).Received11February;accepted21April;publishedonline23May2010;doi:10.1038/ng.5