Fine Mapping And Function Of A Single Grain Substitution Line In Grain Weight

Rice is one of the most important grain crop.As the increase of population and decrease of production area,enhancing rice yield and rice quality is always the goal that breeding scientists pursue,and grain shape is one of the most critical factors that influences grain yield and grain quality in rice.Therefore,it's very necessary to interpret its genetic mechanism and perfect its grain shape regulatory net.As the method of mapping gene is getting mature,over 500 grain shape QTLs have already been reported,more than 60 grain shape genes have been cloned to research.Through these researches about QTLs and genes,we found out that they mainly constitute grain shape regulatory net by phytohormone pathway,ubiquitin-proteasome pathway,mitogen-activated protein kinase?MAPK?signaling pathway,G-protein signaling pathway and epigenetic modification et cetera ways,and influence each other.In this study,a chromosome segment substitution population with japonica rice Nipponbare as donor parents and indica rice 9311 as recipient,recurrent parent was constructed.A grain weight variation material was found in this fragment substitution population,its phenotype is a decrease in the 1000-grain weight.We performed genetic analysis and genetic mapping on it.,the main results are as follows:1.Compared with the recipient parent 9311,the other traits of the fragmentsubstitution line were not significantly different,but the 1000-grain weight was significantly reduced,and the grain length,grain width,and grain thickness were all reduced.It was speculated that this fragment may control multiple grain type traits?grain length,width,thickness?.2.Through the preliminary detection of 9K-SNP gene chip typing,chromosome 11was found having a linkage site?q GW11?,and further development of Indel polymorphism markers to analyze F₂ population.Then combined with fragment overlap method,the interval was narrowed to three linkage intervals:2.2Mb-2.7Mb?q GW11a?and 4.7Mb-5.4Mb?q GW11b?on the short arm side of chromosome 11 and 25Mb-32Mb on the long arm side of chromosome 2.q GW2.1is linked to a grain-type trait.Among them,q GW2.1 is also related to panicle regulation3.Through genetic analysis of three types of substitution-based polymeric materialparticle type tests,it was found that the three QTLs may be in the same regulatorypathway.In this study,the QTL?q GW11a?with one of the largest effect valueswas first finely located,and then the other two QTLs?q GW11b,q GW2.1?werereversed.The q GW11a was located within the range of about 90kb.4.Use gene sequences for alignment and analysis of transcriptome sequencing data.A candidate gene was mapped in the q GW11a positioning interval.The gene is anamino acid transporter family gene that is expressed during the entire growthperiod of rice.The gene was knocked out in the Nipponbare background,its grainlength and grain width have increased.5.Use this set of fragment substitution lines,single-segment substitution linescontaining GS3 and gw5 were also screened.The two single-segment substitutionmaterials were hybridized with the original substitution line q GW11a,respectively.The results showed that the accumulation of two genes and substitution lines mayhave an additive effect,that is,they regulate rice grain shape through differentpathways.In addition to additive effects,they also show different epistasis,and different pathways may also influence each other.