Mapping Of QTL Associated With Grain Shape And Grain Weight In A Large Grain Rice Variety, Tedaxian

Grain shape is an important component factors of rice yield, and its was controlled by t quantitative trait loci. It's important to detecting, mapping, identifying QTL associated with grain weight and analysis its effects for improving yield and quality. In this study, we selected a large grain parent Tedaxin and Nipponbare to establish F2 population (1500 plants), applying SSR markers, mapping QTL associated with grain shape and grain weight, the main research results are as the following:1. There were 387 pairs of primers with polymorphism between the large grain Indica parent and small grain parent japonica rice variety Nipponbare in the 914 pairs of SSR primers, the polymorphic percentage was 42.3%. Due to the great differences in the genetic background,the polymorphism is higher than average2. Taking account the excessive work of usually method of mapping, we choose the bulked segregatiom analysis (BSA method),in order to save time and improve efficiency:selected large grain size and small seeds each 10 plants from F2 population to establish bulked pools,387 pairs of SSR markers were screened between the bulked pools, and further identificated by small groups composed by 72 plants small grains,and a major groups total of 228 plant composed of 145 small grains and 83 large grain.There were eight molecular markers detected associated with grain shape and gain weight traits, including 6 on chromosome 2,2on chromosome 3.3. It is 6.2cM from grain shape QTL to marker RM6295 on chromosome 2 and 11.7cM to marker RM7370 on chromosome 3 named qgs2 and qgs3 temporarily. Using New multiple Range Method to analysis variance on target traits with different plant genotypes in single factor, we found that, qgs2 on grain length can control grain length,grain width and grain thickness, and finally lead to significantly increase in grain weight, suggesting qgs2 may be a major large grain gene. Although qgs3 plays a little effect on each character phenotypes of grain, it add effect with qgs2, thus indirectly control grain length. 4. The next step will be increasing the molecular markers density between located regions, expanding the number of the mapping population and establish advanced permanent mapping population, so as to achieve fine mapping and cloning, analysis mechanism of the formation of large grain seed, provide theoretical guidance in selection of new varieties with higher yield grain and better quality.