GENE-TRANSFER BETWEEN CANOLA (BRASSICA-NAPUS L AND BRASSICA-CAMPESTRIS L) AND RELATED WEED SPECIES

Brassica species are particularly receptive to gene transformation tec hniques. There now exists canola genotypes with transgenic herbicide r esistance for glyphosate, imidazolinone, sulfonylurea and glufosinate herbicides. The main concern of introducing such herbicide resistance into commercial agriculture is the introgression of the engineered gen e to related weed species. The potential of gene transfer between cano la (Brassica napus and B. campestris) and related weed species was det ermined by hand pollination under controlled greenhouse conditions. Ca nola was used as both male and female parent in crosses to the related weed species collected in the Inland Northwest region of the United S tates. Weed species used included: field mustard (B. rapa), wild musta rd (S. arvensis) and black mustard (B. nigra). Biological and cytologi cal aspects necessary for successful hybrid seed production were inves tigated including: pollen germination on the stigma; pollen tube growt h down the style; attraction of pollen tubes to the ovule; ovule ferti lisation; embryo and endosperm developmental stages. Pollen germinatio n was observed in all 25 hybrid combinations. Pollen tubes were found in the ovary of over 80% of combinations. About 30% of the hybrid comb inations developed to the heart stage of embryo development or further . In an additional study involving transgenic glufosinate herbicide re sistant B. napus and field mustard it was found that hybrids occurred with relatively high frequency, hybrids exhibited glufosinate herbicid e resistance and a small proportion of hybrids produced self fertile s eeds. These fertile plants were found to backcross to either canola or weed parent.