Expression of GFP and Bt transgenes in Brassica napus and hybridization with Brassica rapa

It is possible to monitor the movement of transgenes by tagging them with g reen fluorescent protein (GFP). In order to develop a model to study transg ene flow, canola (Brassica napus ev Westar) was transformed with two GFP co nstructs, mGFP5er (GFP only) and pSAM 12 [GFP linked to a synthetic Bacillu s thuringiensis (Bt) cry1Ac endotoxin gene]. Transformed callus sectors tha t fluoresced green were preferentially selected in the tissue culture proce ss. Four independent GFP canola events and 12 events of GFP/Bt canola were regenerated through tissue culture. GFP fluorescence was macroscopically de tectable throughout the entire life cycle of canola. The GFP/Bt events were insecticidal to neonate corn earworm. (Helicoverpa zea) larvae and prevent ed herbivory damage. Fluorescence intensity at 508 nm. varied between the i ndependent transformation events, and ranged from 7.6 x 10(5) to 13.8 x 10( 5) (counts per second) in contrast with the wild-type at 5.3 x 10(5) cps. N ine GFP/Bt and three GFP events were hybridized with three wild accessions of B. rapa. The resultant hybrids fluoresced green and were insecticidal to neonate corn earworm larvae to the same degree as the transgenic canola pa rents. However, fluorescence intensities of the hemizygous F-1 hybrid lines were lower than the respective original homozygous canola parents. Each F- 1 hybrid line was backcrossed by hand onto the B. rapa parent, and transgen ic backcrosses were produced at rates ranging from 15% to 34%. These data s uggest that GFP can be used as a tool to monitor transgene flow from crop s pecies to wild relatives.