QTLs Analysis Of Rice Grain Shape By Using Advanced Backcross Populations

Grain quality is one of the important breeding traits. It is very important to detect, isolate and clone QTLs conferring grain quanlity and grain shape for the rice breeding. In recent years, we developed a lot of advanced backcross populations in the genetic background of indica variety Zhenshan97B (ZS97B), the parent of hybrid Shanyou63, through backcrossing the varieties widely collected from the international elite rice germplasm as donor with Zhenshan97 as recurrent parent. In this study, three advanced backcross populations derived from two donors, indica variety KDML105 and japonica variety Nipponbare, were used to analyze grain shape QTLs. The main results are as follows:1. An advanced backcross population (05LM077) derived from ZS97B/KDML105 were used to detect grain shape QTLs through bulked segregent analysis and interval mapping. Two QTLs of grain length qGL3 with major effect and qGLl with minor were found with the total genetic variance of 31.3% explained. One QTL, qGW5, detected for grain width with the explained variance of 31.3%. Two QTLs of grain length to width, qGS3 with 16.6% variance explained and qGS1 with about 10.0%. Two grain volume QTLs were revealed with qGV3 accounted for 8.12% variance and qGV5 accounted for 16.5%. The additve effects were found between qGL3 and qGLl, the latter may be a newly detected QTL.2. Other advanced backcross population (05LM069) derived from ZS97B/Nipponbare were also used to discover grain shape QTLs through the same strategies. Only one major grain length QTL, qGL3, could account for the total variation of 17.8% in the population. A novel QTL, qGW1 for grain width, explained the variance of 19.7%. One QTL of grain length to width qGS3 were found with 11.5% variation explained. Two new QTLs of grain thickness, qGT1 and qGT9, explained the variances of 9.3% and 11.6% respectively. qGV3 for grain volume detected with the explained variance of 8.7%.3. The third advanced backcross population (06TYC342) derived from ZS97B/KDLM105 were used to identify grain shape QTLs by ANOVA analysis. The pleiotropic effects of a newly detected QTL that flanked by RM7-RM232 on chromosome 3 were found on grain length, grain width and length/width. Similar effect of a QTL nearby RM468 on chromosome3 was revealed on grain length, thickness and volume. The QTL nearby RM128 on chromosome 1 were detected pleotropic effects on grain width, length /width and grain volume.