Community Research and Development Information Service - CORDIS

Safety assessment of the deliberate release of 2 model transgenic plants

The transfer of introduced genes to wild relatives is one of the questions raised by the use of genetically modified sugar beet. While the significance of such a gene transfer must be evaluated on a gene by gene basis, a study of gene transfer using a genetic markers can provide useful information on sugar beet pollen movement and hybridization with related species under field conditions.

The first field experiment with flowering transgenic sugar beet was conducted in Belgium in 1991. The objective of the study was to test experimental protocols designed to study sugar beet pollen movement and hybridizations with Beta maritima. The pollen source was a sugar beet breeding line, containing genes for both Roundup tolerance and beta-glucuronidase (GUS) activity. Pollen movement was monitored by the use of single row plots of male sterile Beta vulgaris plants planted downwind form the pollen source, at distance of 25, 50 and 75 m. Mixtures of Beta maritima genotypes were planted in 5 directions at the same distance as the male sterile Beta vulgaris. Plants were harvested individually and analysed. Germination levels were generally low, and 3250 GUS assays were performed in total.

The analyses indicated that expression of GUS in the segregating pollen source was 57%, lower than the expected maximum or 75%, possibly because of hybridization with the nontransgenic segregants. On the CMS plants at distance zero, 48% of the germinating seeds were GUS positive (50% expected). The comparable frequency of outcrossing decreased with distance from the transgenic pollen source, to 14%, 5% and 3% of the germinated seeds at distances of 25, 50 and 75 m respectively. The level of germination of seeds harvested for Beta maritima plants was extremely low. Of more than 15 000 seeds harvested at distances of greater than 25 m, some 1000 seeds germinated. Only 2 of these seeds were confirmed to be GUS positive; 1 located at 25 m from the pollen source and the other at 75 m.

Reported by

Monsanto Europe SA
Technical Center Europe/Rue Louis Burniest
1348 Louvain-la-Neuve
Belgium
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