Intergeneric hybrids between Brassica napus and Orychophragmus violaceus containing traits of agronomic importance for oilseed rape breeding.

Protoplast fusions between Brassica napus and Orychophragmus violaceus for transfer of valuable traits to oilseed rape resulted in 257 somatic hybrid plants. Hybridity was confirmed by morphological, cytological and molecular means. Symmetric fusions gave rise to 131 plants. Fifty eight of these plants had an intermediate morphology and contained nuclear DNA corresponding to the sum of the parental species. All 131 plants were sterile with no pollen grains observed upon flowering. Another 126 plants were derived from asymmetric fusions in which protoplasts of the donor parent O. violaceus were irradiated by 100 or 200-Gy X-rays prior to fusion. Morphologically these plants showed a larger variation compared to the plants regenerated from symmetric fusion experiments. In contrast to plants obtained from symmetric fusions, fertile hybrids were recovered among regenerants from the asymmetric fusions. Twenty four of these plants released viable pollen grains and 14 of the determined 17 plants set seeds after either selfing or backcrossing to B. napus. Fourteen male-sterile plants were identified with female fertility. This observed male sterility most-likely originated from alloplasmic recombination and would be of great potential for the development of a new cytoplasmic male sterility system. The fatty acid composition of the fertile hybrids and their progenies showed a biased distribution towards the B. napus parent, which has a high erucic acid-content type. However, increased levels of palmitic and linoleic acids compared to B. napus were found in subsequent generations, as well as a reduced level of erucic acid.