Obtaining And Genetic Stability Of Chinese Cabbage-cabbage Translocation Lines With Fragment Of Cabbage Chromosome 7

Translocation line is an individual formed by one-way or reciprocal translocation between chromosomes of two different species. It is significantly important for the application of excellent exogenous gene to study the genetic stability of exogenous chromosome in translocation lines. In order to obtain Chinese cabbage-cabbage translocation lines, Chinese cabbage-cabbage alien addition line 7#(AC7)were used as experimental materials in present study. Using specific In Del markers( compared with Chinese cabbage) distributed in linkage group NO.1 of cabbage, and combining with cytological observation, 3 translocation lines were identified from backcross progenies of BC1 microspore plants and M2 obtained by backcrossing irradiated pollens of AC7 with Chinese cabbage 85-1. Using specific In Del markers of cabbage, progeny plants from selfing, backcrossing and microspore culture were identified. The main results are shown as follows:1. Using rays 60Co-γ radiating pollens of AC7, M1 plants were obtained by backcrossing irradiated pollens with Chinese cabbage 85-1, and then M2 plants were obtained by selfing M1. Using 31 specific In Del markers(compared with Chinese cabbage)distributed in linkage group NO.1 of cabbage, and combining with cytological observation,14 translocation lines were identified from selfing progenies of M2 plants. Two translocation lines were identified by two specific In Del markers,C01-1 and C01-2, with physical location of 206635-283038 bp and size of about 76 Kb. Another 12 translocation lines were identified by seven specific In Del markers C01-1, C01-2 C01-3, C01-4, C01-5,C01-6 and C01-7.2. Two translocation lines AT7-1 and AT7-2 with different chromosome fragments of cabbage were selected and studied from 14 translocation lines of M2, for which isolated microspore culture, selfing and backcrossing were further performed. Using specific In Del markers of cabbage, progeny plants from selfing, backcrossing and microspore culture of above two translocation lines were identified. The results showed that genetic stability of two translocation lines AT7-1 and AT7-2 with different chromosome fragments of cabbage was different. The genetic stability of selfing progenies, backcross progenies and microspore culture plants in the same translocation line was also different. In AT7-1, the ratio of keeping exogenous fragment in selfing progenies, backcross progenies and microspore culture plants was 73%, 28% and 50%, respectively. In AT7-2, the ratio of keeping exogenous fragment in selfing progenies, backcross progenies and microspore culture plants was 84%, 62% and 25%, respectively.3. Using 31 specific In Del markers(compared with Chinese cabbage)distributed inlinkage group NO.1 of cabbage, one plant was identified from backcross progenies of BC1 plants which is not radiated, for which isolated microspore culture were further performed.Using specific In Del markers and combining with cytological observation, one translocation line was identified from the microspore culture plants of BC1 and named AT7-3,which was identified by seven specific In Del markers C01-1, C01-2 C01-3, C01-4,C01-5, C01-6 and C01-7.4. Using 31 specific In Del markers of cabbage and combining with cytological observation, the genetic stability of AT7-3 was analyzed. The results showed that the ratio of keeping exogenous fragment in selfing progenies of microspore translocation lines AT7-3 was 100%. The microspore translocation lines AT7-3 was homozygous translocation lines, in which tthe exogenous chromosome could be stable heredity.5. Field characters of selfing progenies of translocation lines AT7-3 from nonradiation BC1 microspore culture and two translocation lines AT7-1 and AT7-2 from radiation were investigated, and were compared with that of the controls diploid Chinese cabbage 85-1 and cabbage 11-1. The results showed that there were no clear differences in phenotypic triats at vegetative growth stage between selfing progenies of AT7-2 and one parent Chinese cabbage 85-1, while selfing progenies of AT7-1 had good heading. AT7-3selfing generations plant were small. The head of AT7-3 selfing generations plant were not tight. The results of nutritional quality identification indicated that the soluble sugar content of selfing progenies of AT7-1, AT7-2 and AT7-3 were higher than that of the parent Chinese cabbage. But dry matter content of selfing progenies of AT7-1, AT7-2 and AT7-3 was lower than that of the parent Chinese cabbage.