SEXUAL HYBRIDIZATION IN CROSSES OF CULTIVATED BRASSICA SPECIES WITH THE CRUCIFERS ERUCASTRUM-GALLICUM AND RAPHANUS-RAPHANISTRUM - POTENTIALFOR GENE INTROGRESSION

Studies were conducted to investigate the crossability of the cultivat ed Brassica species, Brassica napus (oilseed rape), B. rapa (turnip ra pe), and B. juncea (brown and oriental mustard), with two related cruc iferous weeds that are abundant in certain regions of Canada, Erucastr um gallicum (dog mustard) and Raphanus raphanistrum ssp. raphanistrum (wild radish). Seed was produced without recourse to embryo rescue fro m all reciprocal crosses except R. raphanistrum x B. juncea. Four hybr id plants were recovered, namely B. napus x E. gallicum, B. napus x R. raphanistrum (two plants), and B. rapa x E. gallicum. The hybrids wer e characterized by their morphology, RAPD analysis, and cytological ex amination. The B. rapa x E. gailicum hybrid was extremely vigourous an d fertile, and would likely grow in natural habitats. This hybrid prod uced self-seed and backcrossed readily with the B. rapa parent and, to a lesser extent, with the E. gallicum parent. The B. napus x E. galli cum hybrid was a weak plant, but produced fertile backcross progeny wi th the E. gallicum parent. The B. napus x R. raphanistrum hybrids were vigourous but mostly sterile. Because of their low vigour and/or ster ility, hybrids produced from crosses of B. napus with the cruciferous weeds would not likely be an environmental concern. However, the poten tial of the B. napus x E. gallicum and B. rapa x E. gallicum hybrids t o backcross with E. gallicum may be of concern.