Fine Mapping Of QTLs For Thousand Grain Weight And Grain Size Of Rice Choromosome1

Grain weight is one of the three component of rice yield traits. Grain weight isdeterminted by grain size (grain length, grain width and grain thickness), grainfilling and starch content. Understanding QTLs that control thousand grain weight andgrain size traits is great significant for rice breeding.In this study, Five residual heterozygous lines(RHLs) carrying heterozygoussegments in interval RM151-RM5359with the background of parental mixture wereselected from the recombinant inbred lines of Zhanshan97/Miyang46. F2:3populations of the five RHLs were grown in the experiment field of ZhejiangAcademy of Agricultural Sciences in Quzhou of Zhejiang province. After harvestingseeds, we detected their thousand grain weight, grain length and grain width. Thetarget region RM151-RM5359were confirmed existing an QTL qtgw1that controlsrice thousand grain weight and an QTL qgl1that controls rice grain length. And theallele for increasing thousand grain weight and grain length is from the maternalparent Zhenshan97.Using simple sequences repeat marker(SSR) detection, four individual plantswith the heterozygous segments in interval RM151-RM3746，RM151-RM10402，RM10381-RM10425and RM1344-RM10425were selected, and their F2populationwere developed. We selected three individual plants with the heterozygous segmentsin interval RM10381-RM10402，RM10390-RM10425and RM1344-RM10425, anddeveloped their F2population. With the QTL analysis results of four F2populationsand the method of analysis of the overlap recombinant chromosome segmentsubstitution lines, we narrowed the QTL qtgw1controls thousand grain weight andQTL qgl1that controls rice grain length in RM10381-RM10404, a DNA fragmentapproximately246.6kb in length. The QTL qtgw1increased0.64-0.71g in thousandgrain weight and the QTL qgl1increased0.10-0.12mm in grain length.There are one cloned gene Gn1a controlling grain number and a fine mapped QTL SPP1controlling the number of spikelets per panicle around qtgw1and qgl1bycomparing their physical location. The qtgw1locates behind gene Gn1a, but coversthe whole region of the QTL SPP1. We should futher investigate that if QTL qtgw1,qgl1and gene Gn1a were the same gene. Grain number and thousand grain weight areimportant components of rice yield trait, to futher study this DNA region will be quitehelpful for increasing rice grain yield.In this study, QTL controlling grain width was detected as a minor QTL. It mightbe greatly affected by genetic background and environment.