The project is aimed at providing scientific data for the assessment of the implications which food products derived from crops transformed and expressing new traits may have for the consumer, the food industry and the Community. The project involves a close collaboration between partners skilled in complementary technological expertise required for a multidisciplinary approach towards the aim of the project.
2 different aspects of transgenic food crops, agronomical and processing quality and food safety, have been analyzed. Transgenic tomato was chosen as a model involving 3 different recombinant proteins (the CRYIAb protein conferring insect resistance to theplants and the PAT and NEO proteins which are often used as markers for selection of transgenic plants during the in vitro culture phase).
Analysis of CRYIAb and transgenic tomato plants expressing this protein was emphasized. Analysis of marker proteins was not treated as exhaustive.
The data obtained are related to in vitro and in vivo stability of the proteins. The rationale behind the strategy is based on the known toxic effects of the CRY proteins against insects and the high specific action of the protein needed to be confirmed, as the protein expressed in the plants is not the inactive protoxin, normally activated through proteases in the insect midgut, but the actual toxin. Different in vivo and in vitro assays to study safety aspects of recombinant proteins have been worked out in detail and their relevance was evaluated thoroughly. The thorough analysis of the mode of action of CRY proteins in insects and the methods developed in the research have led to the development of techniques which allow the study of the presence of specific receptors for CRY proteins in a wide range of mammalian tissues and organs, including humans.
The results obtained in the different assays show that the toxic effects observed in insects are indeed highly specific and that no adverse effect of ingestion of CRYIAb proteins could be expected.
In addition a start was made to evaluate potential pleiotropic effects in the transgenic plants by analysis of tomatine as an example.
Agronomical evaluation and processing quality analysisof transgenic plants is underway.
The development and application of genetic engineering techniques has led to the introduction of several important traits in a number of crops. Many of these developments are already extensively being tested under normal conditions of agricultural practice and the first transgenic seeds will soon be ready to be marketed. Although several of these applications are moving into the next phase of development, the evaluation of transgenic crops has thus far mostly been concentrated on yield and behaviour in open field conditions and potential risks associated with the deliberate release of genetically modified plants in the environment. Methodologies and detailed analysis of the putative effects of foreign gene products, which are encoded by the introduced traits, in plant organ systems used for human consumption are urgent.
To analyze the fate of foreign gene products in plants at different preharvest and postharvest stages, we have chosen three model systems, which also have practical applications as new traits. They consist of the enzymes neomycinphosphotransferase II encoded by the neo gene, which is used as a selectable marker in plant transformation, phosphino-thricinacetyltransferase encoded by the bar gene, which confers plant resistance to a broad spectrum herbicide and a bt gene fragment encoding the toxic fragment of an insect controlling protein. Tomato expressing the respective genes will be used as a model crop.
This project is aimed at evaluating detection methods for residues of these foreign proteins. Transgenic lines of a tomato cultivar expressing the above mentioned genes are already available, and will be immediately useful for analysis. These genes will also be transferred into several tomato lines whose fruits are relevant to the processing industry. Tomatoes will be harvested from the transgenic plants and different characteristics, as a function of the consumer's end product, will be evaluated. The behaviour of the plants and their fruits will be thoroughly evaluated for their morphological and biochemical characteristics.
Research on the toxicology of the newly introduced proteins to plants and humans will be performed according to the most severe conditions and principles that are currently applied in this type of investigations. Based on in vitro and in vivo studies, the potential toxicological effects of these proteins will be assessed. This set of experiments should be considered as a first approach for safety evaluation of human consumption of food products in which new proteins have been expressed. The implications of the first generation of transgenic crop plants for the food industry of the community will be assessed. Both the practical and regulatory hurdles of bringing transgenic plants up to the point of commerce will be confronted and the experience gained will be useful for the industry and the regulators alike.
Funding SchemeCSC - Cost-sharing contracts
81015 Piana Di Monte Verna Caserta
6700 AE Wageningen