Correlated Expression of gfp and Bt cry1Ac Gene Facilitates Quantification of Transgenic Hybridization between Brassicas

Abstract

Gene flow from transgenic oilseed rape (Brassica napus) might not be avoidable, thus, it is important to detect and quantify hybridization events with its relatives in real time. Data are presented showing the correlation between genetically linked green fluorescent protein (GFP) with Bacillus thuringiensis (Bt) cry1Ac gene expression in hybrids formed between transgenic B. napus “Westar” and a wild Chinese accession of wild mustard (B. juncea) and hybridization between transgenic B. napus and a conspecific Chinese landrace oilseed rape. Hybrids were obtained either by spontaneous hybridization in the field or by hand-crossing in a greenhouse. In all cases, transgenic hybrids were selected by GFP fluorescence among seedlings originating from seeds harvested from B. juncea and the Chinese oilseed rape plants. Transgenicity was confirmed by PCR detection of transgenes. GFP fluorescence was easily and rapidly detected in the hybrids under greenhouse and field conditions. Results showed that both GFP fluorescence and Bt protein synthesis decreased as either plant or leaf aged, and GFP fluorescence intensity was closely correlated with Bt protein concentration during the entire vegetative lifetime in hybrids. These findings allow the use of GFP fluorescence as an accurate tool to detect gene-flow in time in the field and to conveniently estimate Bt cry1Ac expression in hybrids on-the-plant.

Key words

Brassica napus - Brassica juncea - GFP-Meter - transgene monitoring - Bt protein concentration - hybridization frequency.

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Editor: R. Mendel