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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

ASSESSMENT OF GENE FLOW IN TRANSGENIC TOMATO CROP

TOMASSOLI L., LUMIA V., BARBA M.

Istituto Sperimentale per la Patologia Vegetale, Via C.G. Bertero 22, 00156 Roma, Italy

virologia@ispave.it

gene flow, transgenic tomato, cross-pollination, risk assessment

Tomato (Lycopersicon esculentum L.) is predominantly a self-pollinated crop and, up to now, no cross-pollination have been reported with wild Lycopersicon species and closest relatives (genus Solanum). Natural cross-pollination in tomato may occur with percentages ranging from 0,5% to 10% depending on variety characteristics, environmental condition and pollinators.

As vertical gene flow is considered an important requisite for risk assessment of genetically modified crop, crossability of transgenic tomato plants was evaluated.

In our laboratory, different tomato varieties were genetically modified for cucumber mosaic virus (CMV) resistance using the coat-protein (CP) strategy and neomycin phosphotransferase II (NPTII) gene was used as selectable marker.

In a first experiment, no cross-pollination between transgenic and non-transgenic tomato of UC82B variety was ascertained.

In summer 2000, two transgenic tomato varieties, a fresh-market type named INB (used as parent in traditional breeding programmes) and a local ecotype of San Marzano, were released in the same experimental field for evaluating their resistance to CMV under natural viral pressure conditions. Seeds from both untransformed controls were harvested.

Here, we report preliminary data on the ongoing activity aimed at investigating on the potential transgene transfer by pollen within each variety or between the two ones.

More than 3,000 seeds of INB variety were in vitro grown on a MS basal medium containing 200mg/l of kanamycin. After two months of culturing, three seedlings, showing resistance to the antibiotic, were transplanted in the glasshouse under controlled conditions. The presence of CP gene and NPTII gene was detected by PCR only in two seedlings, named RK-1 and RK-2. In both, the expression of the transgenic CMV coat protein was confirmed by serological methods (ELISA, Western blotting).

The analysis of RK-1 and RK-2 progenies is in progress to verify if these seedlings are true “transgenic hybrids” obtained by natural cross-pollination in open field.