Forthetwo-linehybridricesystem,pollensterilityisregulatedbyrecessivegenethatrespondstotemperature.Therecessivegenecontrollingthermo-sensitivegeneticmalesterility(TGMS)isexpressedwhentheplantsaregrowninconditionswithhigherorlowercriticaltemperatures.Totransfertgmsgene(s)controllingTGMStoThairicecultivarsbybackcrossbreedingmethod,amalesterilelinewasusedasadonorparentwhileThairicecultivarsChaiNat1,PathumThani1,andSuphanBuri1wereusedasrecurrentparents.TheBC2F2linesweredevelopedfrombackcrossingandselfing.Moreover,thesimplesequencerepeat(SSR)markersweredevelopedforidentifyingtgmsgeneandthelinkedmarkerwasusedforassistingselectioninbackcrossing.Theidentificationlineswereconfirmedbypollenobservation.TheresultsshowedthesuccessofintrogressionofthetgmsgeneintoThairicecultivars.TheselineswillbetestedforcombiningabilityandusedasfemaleparentinhybridriceproductioninThailand.