Dissection Of QTL Controlling Silicon Content And Fine Mapping Of Chromogen C On The Short Arm Of Rice Chromosome 6

Rice is one of the most important food crops in the world, and high accumulation of silicon is a character distinguishing rice. The colour and lustre is controlled by the C-A-P scheme in rice, and the C (Chromogenfor anthocyanin) gene is a based gene controlling color characters.In a previous study, a QTLs was located on the short arm of chromosome 6 by using recombinant inbred line (RIL) from Zhenshan97B/Milyang46. In present study, the F3 population consisting of 221 lines, derived from the plant which is heterozygous in genomic region flanking by RM587 and RM19784 on the short arm of chromosome 6 and homozygous in other regions of the genome, namely residual heterozygous line (RHL), were used to map QTLs controlling silicon. Seven residual heterozygous line (RHL) displaying different genotype compositions in the genomic region covering probable locations of C gene on the short arm of rice chromosome 6 were selected from the F3 population. Seeds were harvested from each of the seven plants, and the resultant F_2:3 populations were used for fine mapping C gene. The mapping results are summarized as the following:A genetic map containing 15 SSR markers between RM587 and RM19784 was constructed by using 221 F₂ plants. The phenotypic data collected from the 221 F₃ lines, planted to Fu Yang, Zhe Jiang Province in 2005. Three QTLs controlling silicon content in the STS and two QTLs controlling silicon content in the FLS were detected. Three QTLs controlling silicon content in the STS were located in the interval RM225-RM6917,RM6119-RM314 and RM19715-RM19784 with LOD score of 7.9,5.5 and 19.6, respectively. These QTLs peak LOD position 3.0 cM,18.9 cM and 59.8 cM away from RM587, respectively. The additive effects are -0.78%, 0.27% and -0.64%, respectively. The dominants are -0.38%,-0.30% and 0.31%, respectively. The degrees of dominance are -0.49,-1.14 and 0.49, respectively. The variant ratios are 9.8%,6.7% and 28.3%, respectively. Two QTLs controlling silicon content in the FLS were located in the interval RM225-RM6917 and RM19715-RM19784 with all LOD scores of 20.0. These QTLs peak LOD position 3.0 cM and 59.3 cM away from RM587, respectively. The additive effects are 1.02% and 0.78%, respectively. The dominants are 0.98% and -0.32%, respectively. The degrees of dominance are 0.96 and -0.41, respectively. The variant ratios are 26.4% and 32.8%, respectively.C gene was mapped using F₂ population derived from seven RHL planted Lin Shui, Hai Nan Province in 2006. By relating the coloration performances of the populations with the genotype compositions of the RHLs, the C locus was located between rice SSR markers RM314 and RM253. By using a total of 1279 F_2:3 individuals from two populations showing coloration segregation, the C locus was then located between RM111 and RM253, with genetic distances of 0.7 cM to RM111 and 0.4 cM to RM253. Twenty-two recombinants found in the two populations were assayed with seven more markers located between RM111 and RM253, including six SSR markers and one marker for the C gene candidate, OsC1. The C locus was delimited to a 59.3-kb region in which OsC1 was located.