Obtaining And Genetic Stability Of Chinese Cabbage-cabbage Translocation Lines With Fragment Of Cabbage Chromosome 8

In order to create Chinese cabbage-cabbage translocation lines, Chinese Cabbage-Cabbage alien addition line AC8 was radiated by 60Co-γ rays to obtain M1 plants. Doubled haploid lines were further obtained by microcspores culture for selfing and backcross descendants of M1. At the same time M3 generation were obtained by M2 plant selfing. In Del molecular markers were used for detecting the progenies of M3 generation and DH lines. Combining with cytology observation,the translocation lines AT8-1 and AT8-2 of Chinese cabbage was identified, in which chromosome fragment of cabbage chromosome 8 was added. The genetic stability, field characters and nutrients compositions of translocation lines’ progenies were also studied. This study would provide useful materials in breeding of Chinese cabbage. The main results are shown as follows:1. In this study,two hundred and eighty six specific In Del molecular markers between cabbage and Chinese cabbage were used for detecting the microspore culture plants and selfing progenies. Combining with cytology observation, two translocation lines were detected, which were named AT8-1 and AT8-2. AT8-1 derives from DH lines of BC1 from M1 with 60Co-γ rays of 30 Gy, and AT8-2 is from M3 generation with 60Co-γ rays of 30 Gy. These two translocation lines were detected by ten continuous specific In Del makers from cabbage linkage group C03. Selfing and backcross descendants of AC8 without radiatation were also detected by the specific In Del makers, and the selected plants were performed microspore culture. But there was no microspore culture plants detected with specific In Del makers.2. AT8-1 and AT8-2 had the same specific In Del makers. In order to make sure the length of alien cabbage chromosome fragment, both ends were designed intensively. The result of PCR showed that alien chromosome fragment of these two Chinese cabbage translocation lines was about 26651 kb in length from 31117882 bp to 57768834 bp in cabbage linkage group C03.3. AT8-1 was selfed and backcrossed with diploid Chinese cabbage and was hydridized with two Chinese cabbage inbred lines, then their offsprings were identified by specific makers. Results showed that the translocation chromosome fragment of cabbage was instability, the ratio of keeping entire exogenous fragment in selfing progenies, one backcross progenies and two hybridization progenies was 61.1%, 26.3%, 24.2% and 30.0%, respectively. The ratio of keeping entire exogenous fragment in selfing progenies of AT8-2 was 52.9%. In all progeny individuals, we did not find any translocation plants with smaller fragments than in AT8-1.4. Field characters and nutrients compositions of AT8-1’s offsprings were investigated and measured. The result showed that traits of the progenies with cabbage chromosome fragment were similar, so do the plants without translocated chromosome, indicating that the genentic bakgorund of Chinese cabbage in translocation lines was pure. But there were some differences in field characters and nutrients compositions between these two types of plants. The selfing and backcross progenies with cabbage chromosome fragment had no head, and the head of hybridization progenies were soft and light.