Dynamic expression of green fluorescent protein and Bacillus thuringiensis Cry1Ac endotaxin in interspecific hybrids and successive backcross generations (BC1 and BC2) between transgenic Brassica napus crop and wild Brassica juncea

Abstract

The persistence and stability of a transgene encoding a Bacillus thuringiensis (Bt) Cry1Ac insecticidal protein was investigated in hybrids between crop Brassica napus and a recurrent wild Brassica juncea population. Interspecific hybrids (F1) and backcross progenies (BC1, BC2) containing green fluorescent protein (GFP) and Bt genes were successfully produced in the greenhouse. Stable Bt toxin levels were found in hybrid and advanced backcross progenies formed in wild B. juncea. Bt Cry1Ac concentration was significantly lower in BC2 plants than in transgenic B. napus, F1, BC1, while no significant differences were detected among the latter three plant genotypes. A GFP marker gene was used as a scorable marker and indicator of Bt transgene expression. GFP fluorescence intensity was significantly correlated with Bt Cry1Ac concentration at the flowering stage and the pod formation stage in both transgenic oilseed rape hybrids and backcrossed progenies (BC1, BC2). It was demonstrated that GFP was a suitable marker for Bt protein in the backcross of B. juncea, which could facilitate the detection of gene flow and is useful in biosafety management.