Identification Of QTL For Several Grain Types And Fine Mapping Of Qgw6 In Rice

Rice is the most important food crop in the world.More than half of the world's population uses rice as food rations.With the decrease of arable land due to environmental problems,increasing rice yield is of great significance to ensure food security.1000-grain weight is mainly determined by grain length,grain width and grain thickness.It is an important yield and quality character,which directly affects yield and rice quality.It is of great theoretical significance and application value to carry out genetic research on rice grain type.In this study,Shuhui 498,the backbone parent of heavy panicle hybrid rice,was used as recurrent parent,CT11327,a resource material imported from abroad,was used as donor parent,and a stable small grain type strain F771 was screened in BC₄F₄,which showed a decrease in 1000-grain weight and an increase in panicle length.In this study,the grain type of F771 was studied and the following results were obtained:1.Construction of R498/F771 F₂ isolation and localization population.Based on genetic analysis,3 pools and 2 pools were constructed for extremely large grain and extremely small grain individuals respectively,and BSA mixed pool sequencing was carried out.The sequencing results were analyzed to obtain 3 initial localization intervals of the grain type,which are respectively 2.2-6.5M on chromosome 6?qgw6?,3.3-6.9M on chromosome 10?gw10a?and 12.2-15M on chromosome 10?gw10b?.2.According to the results of BSA mixed pool sequencing analysis,polymorphic primers were designed,and a major 1000-grain weight QTL locus qgw6 on chromosome 6 was finely located to 676.5kb by fragment overlap method in F₃extreme single family,and the candidate gene was predicted to be the reported grain type gene HGW.3.To screen polymorphic primers designed for extreme lines planted in F₃generation,and to complete the research on the effect of different gene combinations on R498 yield traits in combination with a spike length QTL PL10 located in this population by the laboratory.Through screening,three different gene combinations of polymeric strains were obtained,namely qgw6+PL10,gw10a+gw10b and gw10a+gw10b+PL10.Ear traits and grain type tests of each strain showed that PL10could significantly increase ear length and grain number per ear,but did not affect grain type and 1000-grain weight.R498 type qgw6 can increase 1000-grain weight by increasing grain length and grain width.It is an excellent allele related to 1000-grain weight and shows additive effect.