Abstract:

【Objective】 Chromosome localization of genes is an important work for genetic study and breeding practice. In this paper Dayang AB line and trisomics of Chinese cabbage were used for assigning the male sterile gene to a particular chromosome and screening the molecular markers linked to the locus. 【Method】 Locating the male sterile gene to a particular chromosome was conducted by primary trisomic analysis and χ2 test, and screening the molecular markers linked to the gene locus by AFLP techniques.【Result】 All F1 progenies in the nine combinations derived from sterile line × Tri-1 to sterile line × Tri-9 were male ferterile. This indicated that the male fertility was dominant to the sterility in Chinese cabbage Dayang AB line. Selecting the trisomic(2n+1) plants from each F1 progenies and being selfed or test-crossed to the sterile line, and the results showed that only Tri-4 combination displayed 15.5﹕1 segregation proportion of male fertile plants to male sterile plants in F2 and 3.24﹕1 in Tc (test-cross), which disobeyed Mendelian segregation ratios for a monogenetic factor, while other combinations varied from 2.60:1 to 3.76﹕1 in F2 and 0.81﹕1 to 1.48﹕1 in Tc, which fitted Mendelian segregation proportions (3﹕1 and 1﹕1) for a monogenetic factor. These results indicated that the gene controlling the male sterility of Chinese cabbage Dayang AB line was associated with trisomic 4, i.e. the gene was located on the chromosome 4. Further trisomic analysis based on the chromosomal segregation (assuming the gene closely linked to the centromere ) and on the chromatid segregation(assuming the gene apart from the centromere ) showed that the gene was closer to the centromere . Furthermore, an AFLP marker (E34M49) linked to the sterile gene was preliminarily screened out from 124 random primers. 【Conclusion】 Using primary trisomic analysis and molecular screening techniques, the sterile gene of Chinese cabbage was assigned to chromosome 4 and an AFLP marker (398 bp) linked to the locus was obtained preliminarily.

Key words: Chinese cabbage(Brassica rapa L. syn. B. camperstris L.), primary trisomics, male sterility, gene location, AFLP marker