Breeding The Recessive Genic Male Sterility Line And Its Maintainers Of YU139 By Marker-assisted Selection In Rapeseed (Brassica Napus L.)

Heterosis utilization is an efficient way to improve yields, quality of crops, and highly-efficient pollination control system and excellent parents are the key elements for heterosisi utilization. A recessive genic male sterility (RGMS) of 9012A reported by Chen et al. is an important pollination control system in rapeseed. It is a three-lines RGMS system and no need to require for removing 50% fertile plants in the maternal line in hybrid seed production. It is extremely important and difficult to obtain the homozygous two-type line and temporary maintainer line with same genetic background, while marker-assisted selection in combination with hybridization breeding schedules is expected to greatly improve the breeding efficiency. YU139 as thermo-sensitive cytoplasmic male sterile line was breed by professor Yang and has high oil content, prominent lodging resistance and high combing ability. But there is a risk when YU139 is partial fertility at low-temperature in hybrid seed production.In this study,9012A (ms3ms3ms4ms4RfRf) as the donor parent and YU139 (Ms3Ms3ms4ms4rfrf) as the recurrent parent, were adopted for the breeding of recessive genic male sterility line and its maintainer with the same genetic background as YU139 in rapeseed (Brassica napus L.), by combining traditional backcrossing and molecular marker-assisted selection. The main results are summarized as follows:1. The AFLP technique was used to analyze the background of the 141 sterile plants of the F2 population (9012A×YU139).8 plants with the most similar genetic background as YU139 were backcrossed with YU139 for getting F2BC1.2.148 plants with the genotypes of Ms3ms3ms4ms4Rfrf were identified by using markers WSC1 in the total of 286 individuals of F2BC1.3 target individuals with the most similar genetic background of the recurrent parent were backcrossed with YU139 and selfed, after genetic background selection with AFLP markers. Simultaneity, F2BC2 and F2BC1F2 were obtained.3.34 plants with the genotypes of Ms3ms3ms4ms4Rfrf were identified in the total of 161 individuals of F2BC2, by using Ms3 and Rfloci linked markers BSR2, BSR7, BSR64, WSC1, IBP5-3 and IBP37-3. The SSR technique was used to analyze the background of the 34 plants, and 4 individuals with the closest genetic background to YU139 were picked out and selfed to obtain F2BC2F2.4. Through foreground selection in the total of 384 individuals of F2BC1F2,47 homozygous fertile plants (Ms3ms3ms4ms4RfRf),20 homozygous sertile plants (ms3ms3ms4ms4RfRf) and 20 maintainer plants (ms3ms3ms4ms4rfrf) were selected out. Some of fertile plants(Ms3ms3ms4ms4RfRf) were sib-crossed with the homozygous sterile plants (ms3ms3ms4ms4RfRf), some fertile plants were testcrossed with both 9012A and the temporary maintainer line, and some sterile plants were testcrossed with the temporary maintainer line. The maintainer plants were selfed and testcrossed with 9012A. The results of the inheritance investigation of all the offspring proved that the marker assisted foreground selection was accurate in this study.5. Through foreground selection in the total of 227 individuals of F2BC2F2,23 fertile plants (Ms3ms3ms4ms4RfRf),11 homozygous sterile plants (ms3ms3ms4ms4RfRf) and 11 maintainer plants(ms3ms3ms4ms4rfrf) were picked out. Some fertile plants and maintainer plants were selfed to get F2BC2F3. In the F2BC2F3 population, the homozygous two-types lines (139AB) was obtained by foreground selection, and temporary maintainer (139C) was obtained directly by selfing maintainer plants. The 100% sterility population (CA) was obtained by crossing the homozygous sterile plants with maintainer plants.