CREATE INTERGENOMIC HYBRIDS FOR SEED PRODUCTION IN BRASSICA NAPUS ADDED WITH MOLECULAR MARKERS

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, People's Republic of China

Divergent evolution and artificial selection has made the A and C genomes in Brassica napus (AACC) much different from the A genome in B. rapa (A'A') and the C genome in B. carinata (BBC'C') respectively. If new-typed lines of B. napus with a genomic constitution of A'A'CC or could be developed by interspecific hybridization followed by marker assistant selection, these lines might be used as parents to cross the natural B. napus leading to the A'ACC or A'AC'C intergenomic hybrid seeds produced. Consequently, a strong intergenomic heterosis would be expected. A'AC trigenomic interspecific hybrids of B. napus ?B. rapa were produced. Triploids with vigorous field performance were backcrossed to B. rapa. DNA fingerprinting shown that the average ratio of A'/A+A' in the cells new lines were 55%. New lines were cross-pollinated with a range of cultivars of natural B. napus. The seed yield of partial intergenomic hybrids was 20% higher than that of commercial cultivar in average, 61% higher for the best one than that of commercial hybrid of B. napus. Hexaploid plants (A'A'BBC'C') were obtained through interspecific hybridization between B. carinata and B. rapa. The hexaploids were pollinated with natural B. napus to yield pentaploid seeds with A'AB'C'C constitution.Plants with 38 chromosomes have been obtained after selfing the pentaploid plants. The average ratio of A'C'/ A'C'+AC for the new lines was 51%, varied from 13% to 82%. New lines of B. napus were selected to cross cultivars of natural B. napus. The seed yield in most of partial intergenomic hybrids was higher than, some even 3 times higher than, that of commercial cultivar in small block testing. A high correlation coefficient was detected between the ratio of A'C'/ A'C'+AC of new lines and the seed yield of the combinations.