Pr M Boutry, Faculté d'Agronomie, Université Catholique de Louvain
UCL-FYSA, Croix du Sud, 2-20, B-1348 Louvain-la-Neuve, Belgium
Tel: 32 10 473621 boutry@fysa.ucl.ac.be

Introduction
Plant breeding
Genetic engineering
Risks linked to genetic engineering
Applications
Conclusions

Introduction

Transgenic plants inspire fear. This partly comes from an instinctive apprehension man has always felt when faced with a new technology to which he is not accustomed. However, this irrational fear should be overcome while the applications of genetic engineering to the plant must be evaluated very seriously before being used at a large scale.

Plant breeding

Every living organism develops according to a genetic programme of his own transmitted from generation to generation. This programme is contained in genes (approximately 25,000 to 30,000 in animals and plants) present in the nucleus of each cell. As a result, if plants have different agronomic or nutritional properties, this is because their genetic programmes are different. However, living species are not immutable. They evolve along time because the genome (all the genes) alters. Otherwise, the great diversity of the living world would not exist on this earth. Moreover sexual reproduction is a tremendous renewal factor because for every generation it mixes together half of the genetic information of every parent. This principle is at the root of plant breeding which started some 10,000 years ago, when man settled down to become a farmer. Plant breeding consists in reorganising the genetic information according to crossbreeding between varieties, sometimes between species. Important modifications in cultivated plants occurred which, at first, had few agronomic or nutritional qualities. Plant genetic modification has thus been made since long and at a large scale.

Genetic engineering appeared at the beginning of the seventies and includes a set of techniques allowing to take a gene from one species and transfer it to another. In comparison with conventional breeding, genetic engineering distinguishes itself at two levels. It is not limited to sexually compatible species and it consists in transferring one or a small number of genes, while sexual reproduction mixes several thousands of genes at every crossbreeding.

Risks linked to genetic engineering

There are two types of risks associated to transgenic plants which should be evaluated before any application. First, health risks. Could the genetically modified plant (or extracted food) contain products toxic or allergenic for man and animals ? Scientific methods are available to address this question. One should remember though that conventional breeding, which also results from a modification of the genetic information, is not without any risk. Whatever the technology used to modify the plant species, these need to be appropriately evaluated. In addition, it is normal that transgenic plants and deriving products be clearly labelled as such. Not because there is danger (preliminary tests should set aside this case) but because the consumer has the right to be informed.

Ecological risks must then be considered. Could the gene introduced in a plant crop be transferred, by crossbreeding this time, to wild species ? The answer is rather well known according to species. For example, there are no species sexually compatible with maize. On the other hand, rape can cross with wild relatives. Then comes another question. If there is transfer, does this imply a danger ? It will depend on the gene transferred. Therefore a serious evaluation will have to be made in a controlled environment before releasing the plant into the wild.

What can we await from transgenic plants ? Present applications (resistance to insects or herbicides for example) are still in their infancy. We can hope for much better. Farmers are waiting for more performing plants. For example, rather than growing crops with fertilisers, one could arrange for the plants to use better what is available in the soil. Resistance to insects and pathogens which devastate the crops, or to extreme climatic conditions can be improved. This is the case for example in the developing countries where the losses linked to these problems are important. A recent realisation was the obtaining of tomato or rapeseed plants growing in a salted environment.

For the consumer, the improvement of the quality of food and taste, a better conservation, a composition more balanced with regard to proteins, sugars, lipids as well as the presence of nutritive elements may be considered. For example, a rice containing higher quantities of pro-vitamin A and iron has been produced. Finally, it is considered to make plants produce components for therapeutic or industrial usage. A good example is the production of vaccines in fruits, thus opening the door to edible vaccines at low cost.

Conclusion

Genetic engineering is a new technology which comes in addition to more traditional approaches. In itself, a technology is neither good nor bad. Obviously, it is the usage made of it which determines its use or harmfulness. In no case should we yield to alarmed and irrational screams which see there an invention of devil. Moreover, we should not oversimplify things and consider genetic engineering as the privilege of multinational companies. On the contrary, it is necessary to evaluate very seriously and case by case the health and ecological risks of plants modified by genetic engineering, but also by more conventional approaches. Then we shall be able to face with serenity the numerous applications to be awaited from this new technology.