Mating system in Hirschfeldia incana and hybridization to oilseed rape

Concerns have been raised about the possibility of sexual transfer of herbi cide resistance genes from transgenic crops towards weedy relatives. The av erage rate of spontaneous hybridization between Hirschfeldia incana (L.) La greze-Fossat and oilseed rape (Brassica napus L.) was 0.6 hybrids per plant over 3 years of field experiments using herbicide-resistant oilseed rape a s a pollen donor. Self-incompatibility was shown to be the mating system of most individuals within a population of H. incana, although some plants ha d some ability to self-fertilize, which could mitigate gene flow. Back-cros sing interspecific hybrids to H. incana over five generations showed that i ntrogression was not successful in our experiment.