QTLs Mapping For Protein Content And Crude Fat Content In Rice

With the continuous improvement of people’s living standard, the taste and nutritional value of rice has arouse the attention of consumers. So that improvement of the rice quality has become one of the most important goal of rice breeding. The content of starch, protein and fat in rice corn are the key traits used to measure the quality of rice. The quality of protein in rice corn is much better than that in any other corn. Though the content of protein in rice corn is limited, the ratio of every amino acid in corn is appropriate to be absorbed by human body. Not only is the fat in rice corn not the essential substance of living cells, but the main factor to affect the taste of the cooked rice. Therefore, the content of protein and fat are two of the important indicators in evaluation of rice nutritional quality. Breeding by molecular marker assisted selection(MAS) is one of the most effective strategies for the improvement of rice quality. In this researching, we constructed a recombinant inbred lines (RILs) population with186lines using the combination of Minghui63, which is the restorer line of the best hybrid rice of Shanyou63, and the KDML105, which is a kind of scented rice with excellent quality from the Kingdom Thailand. We had make a orient mapping of quantitative trait loci (QTL) and analysis of genetic effect using the phenotype value of the content of protein and fat in rice corn in RIL-F7population and RIL-F8population based on the genetic linkage map of RIL-F7with113molecular marker, and the main results are as follows:1. As to trait of the content of protein in brown rice,2and3QTL are separately detected in year2009and year2010. The tow QTL detected is respectively located in chromosome6and chromosome11, the LOD value are accordingly2.60and2.61, the addictive effect are accordingly-1.19and-1.12, the ratio to explain the phenotype variance are both5.5%. Two of the three QTLs detected in year2010are in the chromosome3and the other one is in the chromosome12, the LOD value are accordingly2.74,2.69and2.32, the addictive effect are accordingly-1.10,-2.02and-1.48, the ratio to explain the phenotype variance are accordingly6.25%,20.75%and10.93%.2. As to the trait of the content of fat in brown rice, none of QTL was detected in year2010and there were3QTLs detected in year2009, which were separately in chromosome1, chromosome7and chromosome8, the LOD value are accordingly2.44, 2.20and2.59, the addictive effect are accordingly-0.0006,-0.0007and-0.0007, the ratio to explain the phenotype variance are accordingly5.42%,7.30%and6.44%.3. The epistasis analysis of the RILs population revealed that there were2main QTLs, which regulated the content of protein in rice corn, involved the episitasis interation. And the epistasis interaction could occur between QTL and QTL, QTL and NOT-QTL, NOT-QTL and NOT-QTL. The total effect of the14epistasis interaction which had something with the content of fat in rice corn was bigger than the sum of the addictive effect of the3main QTLs, which explained that the phenotype difference in the RILs population was commonly decided by all of epistasis interaction, addictive effect and environmental effect and the epistasis interaction effect was more significant than additive effect.