RISK ASSESSMENT OF OUTCROSSING OF TRANSGENIC RAPESEED TO RELATED SPECIES .1. INTERSPECIFIC HYBRID PRODUCTION UNDER OPTIMAL CONDITIONS WITH EMPHASIS ON POLLINATION AND FERTILIZATION

The risk for a gene dispersal is reported for reciprocal crosses between a transgenic rapeseed variety resistant to the herbicide phosphinotricin and five related species. The first stages after pollination were cytologically observed and fertilized ovaries were established in in vitro culture for the production of interspecific hybrids. A similar classification was observed for the index of pollination compatibility and embryo yield. From the 243 embryos produced, 109 plantlets were obtained in a greenhouse. All the interspecific combinations tested were able to produce hybrid plants. A higher number of hybrids was obtained when rapeseed was used as the female parent. The hybrids had the expected triploid structure except for two amphidiploid, B. napus x B. oleracea, and one amphidiploid, B. napus x S. arvensis, plants with 56 chromosomes. The triploid hybrids were sterile or partially fertile but two of the amphidiploid plants, B. napus x B. oleracea, were fully fertile. The cytoplasm source did not seem to affect the fertility of the hybrids.