Dissection Of The Genetic Basis For "Daqingke" In Hybrid Rice

In recent years, the damage trend of weedy rice in hybrid rice fields was spreading.The presence of a large number of weedy rice could cause serious harm for hybridrice and result in severe economic losses. The molecular mechanism of the weedy riceis still not clear. In the present study, two BC2F2population derived from crossesbetween Shuhui527(recurrent parent), Minghui86(recurrent parent) and Fuhui838(donor parent), from which38and47BC2F3：4introgression lines (ILs) were selectedbased on grain yield per plant (GY). We used the BC2F3：4ILs to make crosses withfour sterile lines (II-32A, XieQingzaoA, Gang46A and Jin23A) to produce8F1. Thenthey were screened for phenotypic evaluation, including heading date and yieldrelated traits in the normal paddy field in three locations (Hefei, Hangzhou andGuangzhou) in2010and another three locations (Hefei, Hangzhou and Guangxi) in2011. QTL associated with heading date and yield related traits were identified usingone-way ANOVA and two-way ANOVA methods with the genotypic and phenotypicdata.1. The results of progeny testing showed that55lines didn’t show any panicleinitiation or flowering in Hefei (named Q population) while late heading in Hangzhouand Guangzhou in2010. The grain yield of Q population was lower than the checkcombinations in Hangzhou, and close to the check in Guangzhou, The grain yield ofNon-Q population in Hefei and Hangzhou is almost the same while lower than thecheck.In2011, progeny testing allowed the identification of44lines that didn’t showany panicle initiation or flowering in Hefei, while late heading in Hangzhou and closeto the check in Guangxi. The grain yield of Q population lower than the check one inHangzhou, and close to the check in Guangxi, The grain yield of Non-Q population inthe three environments is almost the same with the check.2. The results of correlation analysis showed that days to heading (HD) and grainyield per plant (GY) were in very significant positive correlation in Guangzhou in2010, while in other environments were in negative correlations. In Hangzhou, HDand GY were in very significant negative correlation both in2010and2011(r=-0.59and r=-0.53). HD and GY were in negative correlation (r=-0.18) in Guangxi whilethere was no significant correlation in both of the two years (r=-0.02and r=-0.03) inHefei.3. The results of GY QTL detection indicated that38QTLs for grain yield and 18QTLs had stable expression in more than two environments or populations in2010;36QTLs for grain yield and21QTLs had stable expression in more than twoenvironments or populations in20114. The results of HD QTL detection indicated that33QTLs for days to headingand15QTLs for days to heading had stable expression in more than twoenvironments in2010;23QTLs for days to heading and12QTLs for days to headinghad stable expression in more than two environments in2011. qHD8-1and qHD8-2for heading date, were detected in all of the four populations and two environments(Hangzhou and Guangzhou), which indicated that they may be the major locicontrolling heading date and related to the occurrence of weedy rice.5. Four pair (RM331and RM2;RM331and RM5346;RM3395and RM16;RM3325and RM53) epistatic QTLs affecting heading days have pleiotropism in2010and five (RM110and RM565;RM110and RM566;RM84and RM579;RM1381andRM179;RM1381and RM481) in2011were detected by two-way ANOVA at morethan two environments, and at the same time, they both control grain yield and hadstable expression in two environments. The detection suggested that the geneinteraction of these loci is the reason of Daqingke in hybrid rice.