Characterization of interploid hybrids from crosses between Brassica juncea and B. oleracea and the production of yellow-seeded B. napus

Yellow-seeded was for the first time developed from interspecific crosses using yellow-seeded (AABB), yellow-seeded (CC), and black-seeded artificial (AACC). Three different mating approaches were undertaken to eliminate B-genome chromosomes after trigenomic hexaploids (AABBCC) were generated. Hybrids (AABCC, ABCC) from crosses AABBCC x AACC, AABBCC x CC and ABCC x AACC were advanced by continuous selfing in approach 1, 2 and 3, respectively. To provide more insight into genome evolution and the cytological basis for resynthesis in each approach, B-genome chromosome pairing and segregation were intensively analyzed in AABCC and ABCC plants using genomic in situ hybridization methods. The frequencies at which B-genome chromosomes underwent autosyndesis and allosyndesis were generally higher in ABCC than in AABCC plants. The difference was statistically significant for allosyndesis but not autosyndesis. Abnormal distributions of B-genome chromosomes were encountered at anaphase I, including chromosome lagging and precocious sister centromere separation of univalents. These abnormalities were observed at a significantly higher frequency in AABCC than in ABCC plants, which resulted in more rapid B-genome chromosome elimination in the AABCC derivatives. Yellow or yellow-brown seeds were obtained in all approaches, although true-breeding yellow-seeded was developed only in approaches 2 and 3. The efficiency of the construction approaches was in the order 1 > 3 > 2 whereas this order was 3 > 2 > 1 with respect to the construction of yellow-seeded . The results are discussed in relation to genome evolution and the development and utilization of the yellow-seeded obtained here.