Development Of Introgression Lines Of Common Wild Rice (O.rufipogon Griff.) From Dongxiang In Jiangxi Province And Mapping QTLs For Improving Yield

The common wild rice is the ancestor of cultivated rice (O.sativa L.). To search beneficial genes from wild rice which have been lost or weakened in cultivated rice is one of the important researches on rice resources and breeding. In this study, an advanced backcross population (BC,)) derived from 94W1, an accession of common wild rice (Oryza rufipogon Griff.) from Dongxiang in Jiangxi Province of China, originated from the most habitat of wild rice (28?4'N), endure -12.8 C in winter and has other beneficial characteristics, such as reaction to drought, good quality etc. as a donor, and an Indica cultivar (O.sativa L.) which had the record of 15 ton/ha in Yunnan Province, "Guichao 2", as a recipient, was used to identify quantitative trait loci (QTL) associated with yield and its components using advanced backcross QTL analysis (AB-QTL). To fully exploit the genetic potential of O .rufipogon, a set of introgression lines were developed in the background of "Guichao 2", and the graphic genotypes of these introgression lines were got. Moreover, the number, length and location of introgressed segments from O. rufipogon were analyzed. The main results were as follows:1. Based on the genotypes of BC4F1 population and the investigation of plant height, yield and its components of BC4F2, a total of 63 QTLs were detected. 2 QTLs on chromosome 2 and 11 from O. rufipogon could increase the yield of "Guichao 2" by 24.96% and 22.54%, respectively. The QTL on chromosome 2 (qGY2-l) explaining 17% of the phenotypic variance is a major gene, which did not coincide with any previously published QTLs in rice.2. A total of 159 introgression lines were developed in the background of "Guichao 2" by marker associated selection (MAS). The average number of each introgression line was 3.08, and the introgressed segments of 159 introgression lines represented 67.5% of the genome of O. rufipogon. Of 159 introgression lines, 23 introgression lines with a single homozygous introgressed segment of O. rufipogon and 14 introgression lines with a single heterozygous one were got.3. According to the genotypes of 159 introgression lines, their graphic genotypes were drew using GGT software, and the ratios and lengths of two parents' segments (heterozygous and homozygous) were obtained.4. The nearly isogenic lines with QTLs influencing plant height as material, two major QTLs associated with plant height were identified and their phenotypic effects were analyzed.5. The majority of introgressed segments from O. rufipogon was less than 10 cM, and these segments were only detected by a single SSR marker. Each of these introgressoin lines had 0-8 homozygous introgressed segments or 0-7 heterozygous introgressed ones, with an average of 3.08 segments per introgression line. The distribution of the introgressed segments along the chromosomes was not random. The majority of O.rufipogon introgressed segments ( about 71% ) were often terminal position, defined herein as including distance less than 15 cM from the end of the chromosome.6. There existed different introgressed frequencies among the 12 chromosomes. Among 491introgressed segments, 87 introgressed segments existed on chromosome 1, while only 14 on chromosome 7. Furthermore, the transmission and fixation of O.ruflpogon introgressed segments varied for individual chromosomes. For example, up to 91.3% of chromosome 2 carried with O.rufipogon introgressed segments, while for chromosome 3, the coverage was only 27.4%.