Pyramiding Effects Of Cooked Rice Elongation QTLs Based On SSSLs In Rice(Oryza Sativa L.)

Rice is one of the most important food crops in the world.It has very important significance for crop genetic improvement to identify and map agronomic trait locus,and apply them in pyramiding breeding.Cooked rice elongation(CRE)is derived from the grain and the cooked rice length and it is a quantitative trait with complex inheritance controlled by multiple genes,CRE also is an important indicator of cooking and eating quality of rice.Single segment substitution line(SSSL)eliminates the interference of genetic backgrounds,and it's one of the important materials of quantitative trait loci(QTL)mapping and polymerization.It's significant for improving rice quality to use SSSLs in pyramiding for CRE.In this study,based on the method of molecular marker assisted selection,a number of multi-segment polymerized lines with more segments were obtained,by using 14multi-segment polymeric materials derived from Basmati 370 and BG 367,and the polymerization rate of these aggregates was measured and the polymerization effect was analyzed.The main results are as follows:1)A total of 107 multi-segment polymerized lines were obtained by screening 14 of the multi-segment polymeric materials,including 33 six-segment polymerized lines,33 seven-segment polymerized lines,4 eight-segment polymerized lines,22nine-segment polymerized lines and 15 ten-segment polymerized lines.Among them,there were 9 different combinations in the six-segment polymerized lines,and 6different combinations in the seven-segment polymerized lines.There were only one combination in the eight-segment polymerized lines,one combination of the nine-segment polymerized lines,and also only one combination of the ten-segment polymerized lines.2)The CRE of 107 multi-segment polymerized lines was determined and the epistatic effect was analyzed.The results showed that with the increase of the numbereffect gradually increased.In the early season of 2016,the CRE rates of the six-segment and seven-segment polymerized lines were 73.85% and 74.12%,respectively.The CRE rates of 4 polymerized lines reached a significant level,and the others reached a very significant level.The positive epistatic effects were detected in7 polymerized lines,and the other ones were negative.There were no significant differences in 29 polymerized lines,8 polymerized lines were significant levels,and the remaining 31 polymerized lines reached extremely significant levels.The CRE rates of the six-segment,seven-segment,eight-segment,nine-segment and ten-segment polymerized lines were 74.21%,72.63%,73.67%,72.34% and 73.30%,respectively.And the negative epistatic effect was detected in all 107 homozygous lines in late season of 2016,one of which was not significant,and 2 polymerized lines reached a significant level,and the other 104 reached the extremely significant level.3)Among the 9 six-segment polymerized lines and 6 seven-segment polymerized lines,some materials with good cooked rice elongation were obtained,such as six-segment polymerized lines 11-02/11-03/11-04/11-12/11-01//04-7 and seven-segment polymerized lines 11-02/11-03/11-04/ 11-12/11-01//04-7/04-11,whose CRE rates were 77.69%,and 76.81%,79.75% and 76.91%,epistatic effects were-16.26%and-17.83%,-0.24% and-17.99%,respectively in the early and late season of 2016.Their CRE rates were comparatively higher,and the performances were more stable.In this study,a number of multi-segment polymeric materials with better cooked rice elongation were obtained by polymerizing QTLs of CRE,which could be applied to breeding practice and provide references and ideas for the cultivation of high yield and high quality.