Fast tracking alien gene discovery by molecular markers in a late flowering Chinese cabbage-cabbage translocation line ‘AT7–4’

Flowering time is an important agronomic trait of Chinese cabbage with late flowering being a primary breeding objective. In our previous work, we obtained Chinese cabbage-cabbage translocation lines that contained several beneficial cabbage genes. Cabbage-specific molecular markers show that these genes were coming from chromosome C01 of cabbage. In this study, we investigated the inheritance of flowering time in a couple of translocation lines and analyzed the transmission rate of molecular markers in the offspring. Consequently, we obtained the late flowering Chinese cabbage-cabbage translocation line ‘AT7–4’ in which the flowering time was later than that of ‘85–1’ by about 7 days under 4-week vernalization. Based on previous studies of the genomes of Chinese cabbage and cabbage, we located the cabbage-specific molecular markers that were closely linked at the top of the chromosome A01 in the F2 mapping population generated by self-crossing F1s derived from a cross between the translocation line ‘AT7–4’ and Chinese cabbage ‘14–36’. Five flowering-related genes in the alien fragment were found by functional annotation and their molecular markers were developed. This study lays the foundation for the future improvement of Chinese cabbage varieties using A-C translocation lines.