Mapping And Verification Of A Grain Size QTLqGS7.1 In Rice

Grain size,which is including grain length,grain width,grain thickness and the ratio of grain length to width,are both important appearance quality and can affect rice yield by affecting grain weight.Grain size is a stable quantitative trait,controlled by nuclear genes.In recent years,significant progress has been made in the study of QTLs localization for grain size in rice,and the major genes for controlling grain size have been cloned successfully.In this study,detection of quantitative trait loci?QTLs?for grain size and weight in rice was conducted using BC₄F₄ populations and its residual heterozygous lines?RHs?derived from a backcross between the recurrent parent Xiaolijing?XLJ?and the non-recurrent parent Dalixian?BG1?.The populations were grown in Lingshui?LS?,Hainan and Fuyang?FY?,Zhejiang.The results were as the follows.1.In 2016,19 QTLs for grain size and weight were detected in Fuyang using 192 backcross inbred lines?BILs?.The main QTLs contained qGL3.2,qGL10,qGW2,qGW5,qLWR3,qLWR5,qTGW2-2,which explained 25.68%,20.80%,22.10%,34.03%,22.55%,24.57%,22.87%of the phenotypic variance respectively.2.In 2017,19 QTLs for grain size and weight were detected in Lingshui using 192 BILs.The main QTLs contained qGW2,qGW3-1,qGW5 and qLWR3,which explained 27.15%,18.65%,26.07%and28.50%of the phenotypic variance.3.Four QTLs located in the RM324-RM5619,C3-18-RM15332,RM500-RM21772,RM23969-RM54002 interval on 2,3,7,9 chromosomes respectively controlling grain length were detected in two years.Two QTLs were located in the RM324-RM2634,C5-5-C5-3 interval on 2,5 chromosomes respectively controlling grain width.Three QTLs were detected in C3-18-RM15332,C5-2-C5-3,RM23969-RM24002 region on 3,5,9 chromosomes respectively controlling the ratio of grain length to width.4.In the RM500-RM21772 interval on chromosome 7,a QTL tentatively named qGL7.1 were detected in two years,the additive effects were 0.60mm to 0.96mm in two environments,explaining11.33%-15.46%of the phenotypic variance.Allele of BG1 was increasing grain length.Six residual heterozygous plants were selected in this interval to construct progeny populations.Therefore,qGL7.1was used as the research focus.5.A QTL was further mapping in the X7-9-RM351 interval,and the QTL has a considerable effect on grain length,grain width and thousand grain weight.This QTL was named qGS7.1.The allele from XLJ increase grain length,width and thousand grain weight form the data analysis.6.qGS7.1 has no influence on many agronomic traits such as heading date,plant height,tiller number,flag leaf length,flag leaf width and so on.We can draw a conclusion that qGS7.1 can be used for rice breeding and it brings little negative effect while regulating grain size and weight.