Comparative Mapping Of Quantitative Trait Loci For Heading Date And Plant Height In Rice Under Long-day And Short-day Conditions Using A Recombinant Inbred Line Population

Rice is an important crop. Heading date has its importance for rice seasonal and regional adaptability. A lot of research have been done about it and revealed part of the molecular mechanism. The recombinant inbred line population derived from the cross between rice varieties Zhenshan97and Minghui63was examined for heading date, plant height and grain length in two plantings in winter nursery in Hainan Island to analyze QTLs under short-day conditions using an ultra-high density SNP linkage map. Comparison of the results from the short-day Hainan winter and7groups heading date,4groups of plant height, and2sets of grain length data from long-day Wuhan summer revealed large differences of QTLs between the two conditions.1. The main QTL for heading date in long-day environment of Wuhan was detected near the centromere of chromosome7, but its effect was not significant in Hainan short-day environment. In contrast a major QTL for heading date was detected in the region of9.12Mb-9.65Mb on chromosome6in Hainan but its effect was not significant in Wuhan conditions.2. The difference between plant height QTL in short-day and long-day environments is similar as the condition in heading date QTL. The main QTL near the centromere of chromosome7in long-day environment drastically reduced its effect in Hainan. On the contrary, the region of8.45Mb-9.65Mb on chromosome6is the main QTL in short-day condition. Grain length QTL remain basically stable in the two places.4heading date QTLs and4plant height QTLs were detected in both2plantings in Hainan.1heading date QTL and1plant height QTL in them are unique in Hainan environment.3. Significant epistasis which is detected in both two plantings of Hainan was widespread in the genome.30digenic interactions for heading date and17for plant height were detected.31digenic interactions are same in all3sets of grain length data in the two places. Each epistasis effect explained about3%-10%of the phenotypic variation.The results contributed to the understanding of the genetic basis of flowering in rice.