The Construction Of Chromosome Segment Substitution Lines In Rice, QTLs Mapping And Analysis For Maximum Root Length And Gene Mapping For Whorled Primary Branch

Rice (Oryza sativa L.) is the world' s most important food crop, and its most traits are quantitative traits, which are controlled by polygenes. To study quantitative trait loci (QTL) by dissecting a QTL into single Mendelian factors is significant in understanding the growth and development of rice, and improving the yield and stress resistance of rice. An important strategy for dissecting a QTL is by constructing chromosome segment substitution lines (CSSL). The advantage of a CSSL in mapping QTLs is that, CSSL eliminate the "noise" of the genetic background. The present research has developed a CSSL population which choromosome segments from Africa Rice {Oryza glaberrima Steud) (donor parent) were introgressed into an elite genetic background of 95-22(recurrent parent), using backcross and marker-assisted selection(MAS). We mapped and analyzed the QTL for maximum root length (Mrl) and the gene for whorled primary branch (Wpb) using 88 chromosome segment substitution lines selected from CSSL population. The main results are as follows:1. The polymorphism between 95-22 and Africa Rice was detected by using DNA markers, including SSR markers, STS markers, and CAPS markers. 118 markers showed definite polymorphism, which covered the whole genome of rice. All these markers covered 1531.1 cM in length with average distance of 14.44 cM between adjacent markers.2. 187 overlapping chromosome segment substitution lines with the 95-22 genetic background have been developed. This CSSL population did not cover the whole genome of rice because 158. 81 cM chromosome regions uncovered by donor parent chromosome segments. The covered percentage is 89.62%.3. We identified 2 QTLs for Mrl on chromosome 7 and 4 QTLs for Mrl on chromosome 2,4,9,10, respectively. And identified a gene for Wpbon chromosome 4.4. We identified 2 new QTLs for Mrl on chromosome 2 and 10 in fine mapping, respectively. To fine map QTL for Mrl on chromosome 2 and Gene for Wpb on chromosome 4. we detected and will detect more polymorphism markers among target regions with putative QTL/Gene and construct saturated linkage map for further fine mapping.