Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.28

ABSENCE OF GENE FLOW IN AN ENVIRONMENTALLY CONTROLLED EXPERIMENTAL GM-RICE FIELD TRIAL

E. LUPOTTO*, J. MESSEGUER**, A. REALI*, E. CONTI*, E. BALDONI*, C. LANZANOVA*, A. MAZZOLENI*, I. SALVALAIO***, S. RUSSO***

*) Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo (Italy)

**) Institut de Recerca i Tecnologia Agroalimentaries – I.R.T.A. Cabrils, Barcelona (Spain)

***) Istituto Sperimentale per la Cerealicoltura, Sezione di Vercelli (Italy)

biotechnology, environmental control, gene flow

Transgene flow from engineered crops to other cultivars or to their wild and weedy relatives is one of the major concerns in relation to the ecological risks associated with the commercial realease of transgenic plants. Rice is a strictly autogamous species and spontaneous outcross is rare, although possible. Previous experiments reported on possible gene flow in open field conditions favoring pollen flow from GM-lines to cultivated rice in proximity (Messeguer et al., 2001). The establishment of strategies aimed at controlling and minimising gene flow and an experimental assessment of the risk associated to experimental conditions adopted for GM-crops segregation, are of major interest for supporting actions of the competent authorities in the matter of deliberate release notifications for scientific studies.

An experimental design has been set up and evaluated with the aim to detect, if any occurred, gene flow related to the trait “herbicide resistance” in rice, obtained with the cassette 35S CaMV-bar, conferring resistance to L-glufosinate, active principle of the herbicide Basta (Liberty) (AgrEvo). A set of three independent events were established as homozygous lines in the spanish rice cultivar Senia. They exhibited clear and stable resistance to the commercial formulation of Liberty, at a level of 1.7g/l. Series of 30 plants per GM-line were sown in an environmentally controlled area, isolated with: i) open space kept weed-free; ii) a cultivated rice variety with higher size and later flowering time respect to the GM-lines. Two hemi-circles around the GM-plot, in the direction of dominant breeze were sampled, the closest at two meters and the second at three meters, with a total number of 160 panicles sampled, taking panicles contemporary flowering to the GM-lines. On an indicative number of 20000 seedlings germinated and sprayed with Liberty, no one resulted L-glufosinate resistance, thus confirming the reliability of the isolation measures adopted. Furthermore, weedy rice, also called red rice, spontaneously proliferates in rice fields and represents a real weed for the rice crop. Complete eradication of red rice is almost impossible due to its characters of shattering, dormancy, and persistence. Gene flow to spontaneous red rice is also of major concern when adoption of herbicide resistance is foreseen, since in a short run it can be envisaged that most of the weedy rice might introgress the resistance gene. Strict avoidance of this occurence is therefore required. Thirty-five spontaneous red rice plants growing at various orientations and distances from the GM-plot were sampled with harvest of panicles contemporary flowering with the GM-plants. On an indicative number of 11000 red rice seedlings treated with Liberty, no one resulted resistant to the herbicide, thus confirming the complete avoidance of cross-contamination during the trial. Molecular studies confirmed absence of the bar gene in some seedlings exhibiting a sligth tolerance in the beginning of their development, which was in any case lethal afterwards. The results obtained from this specific environmental monitoring confirmed the efficacy of the measures adopted for the experimental trial in GM-rice lines isolation.

The research is performed within the framework of the project EURICE (QLK5-1999-1484) co-funded by the European Commission within the 5^th Framework Programme.