Research On Genetics Of Rice Grain Shape And Fine Mapping Of Its Major Qtl

Rice (Oryza sativa L.) is one of the main food crops, and also a model for monocot plant. It provides more than50%of the food for the world population. It has been estimated that it require a40%increase in rice production by2030to meet the growing world population. Therefore, how to increase the rice production with decreased cultivated area has become a serious problem for breeders. Grain yield, a complex agronomic trait in rice, is mainly determined by its three major component traits:number of effective panicles, number of grains per panicle, and grain weight. Most of these complex agronomic traits are controlled by multiple genes, known as quantitative trait loci (QTLs). It does not like single-gene as appear doublets or triplets, but shows a continuous variation. Grain shape is closely related to grain weight that is one of the three major components of rice yield. In addition, it also has a major influence on the market values of the rice products. Therefore, it is very important to understand the genetic mechanisms of rice grain shape.In this paper, we based on the previous research on the mapping and cloning of QTL for grain shape and grain weight, using the super hybrid rice, Liang-You-Pei-Jiu was derived from by a cross between indica93-11and indica Peiai64s, we constructed132recombinant inbred lines by using this super hybrid rice, and combined with high-density SNP genetic linkage map, we detected32QTLs that LOD>2.5which influence grain length, grain length-to-width ratio, grain width, and grain weight by MultiQTL analysis software at Hainan in2012and at Hangzhou in2011. Including seven grain length QTL, eleven grain width QTL, ten grain length-to-width ratio QTL, four grain weight QTL. They were distributed on rice chromosomes1,2,3,4,5,6,7,8,9and11. Among which qGLl.l, qGL3, qGW2and qLWl were detected in both places. And qGL3was found to allelic with GS3that have been reported by further fine mapping and sequencing analysis. By SPSS software (two-tailed t test), we found that grain length to correlate positively with1,000grain weight and grain length-to-width ratio; grain width to correlate positively with1,000grain weight, but to correlate negatively with grain length-to-width ratio. All of the32QTL detected which are controlled by positive additive effect from93-11, negative additive effect from PA64s.A grain length QTL-qGL1.1was selected to further fine mapping by us, which LOD is8.2, contribution up to16.2%(Hainan), and was detected both at Hainan in2012and at Hangzhou in2011, its initial location between SNP marker1-8and SNP marker1-35. According to the sequencing results of93-11and PA64s, we developed many new markers, and combined with2,401F9-generation RIL population and has been constructed BC2F2population (2,887individuals), the qGLl.l was mapped to a540kb fragment of genomic DNA between Indel marker JLK7and Indel marker JLK17.