1. The potato and fungal disease

The potato is one of the world's most important crops. It is superior to all other crops in protein content. The potato contains very high proportions of essential amino acids such as lysine, which is why it forms such a valuable part of human nutrition. Potatoes are cultivated worldwide on an acreage of 17.9 million hectares, in fourth place after wheat, rice, and maize in terms of acreage. In the EU, potatoes were cultivated on an acreage of about 1.4 million hectares.
The most important potato disease in the European Union and worldwide is blight. The disease is caused by a fungus (Phytophthora infestans) that first occurred in Europe in the 1840s (e.g. the great potato famine in Ireland).
The fungus occurs particularly in moist, rainy years. The disease can spread very rapidly throughout the entire crop, destroying foliage and diminishing the growth of the tubers. In addition, infestation with blight promotes soft rot (e.g. Erwinia carotovora). The most important method of containment involves the use of fungicides.

2. Potatoes that protect themselves against pests

In October 1992, a research project entitled "Environmentally-friendly containment of blight and potato rot, a disease caused by Phytophthora infestans" was submitted to the EU by a group of 30 organizations/institutes. The objectives of this project were as follows:

• The reduction of the use of fungicides to contain Phytophthora infestans.

• The development of aids and materials to breed high-quality potato grades with a persistent resistance towards Phytophthora infestans.

• Molecular and biological understanding of the interaction between the potato and Phytophthora infestans.
  Genetic modification is an indispensable tool for the attainment of these objectives.

In addition to Phytophthora infestans, there are a further three potato viruses - namely potato leaf-rolling virus (PLRV), potato virus X (PVX), and potato virus Y (PVY) - and also the bacterium Erwinia carotovora that are responsible for considerable economic losses in the potato-cultivation sector. Intensive research efforts are under way to identify solutions for combatting these organisms, and genetic modification again plays an important role.
In the European Union, there were 157 applications for the release of genetically modified potatoes that had been made by April 1999; the potatoes in question are resistant either towards viruses (20), fungi (22), or bacteria (11).
In the United States and Canada genetically modified varieties of potatoes are on the market that are resistant towards Colorado beetle.

3. Potatoes with a modified starch composition

Potatoes are cultivated not only for the purpose of supplying nutrition. As a raw material, potato starch in particular finds a broad range of applications in a number of industrial sectors. Potato starch is used in particular in the paper and textile industries.
The potato contains two kinds of starch, namely amylose (80%) and amylopectin (20%). Amylopectin is highly suited for the production of glues and pastes, while amylose can be used in the manufacture of, for example, biodegradable foils and films. Amylose and amylopectin must be separated from each other before being industrially processed, and this separation procedure is connected with a high consumption of energy and water.
With the help of genetic modification scientists have succeeded in inhibiting an enzyme in the potato that is responsible for the production of amylose. The resultant transgenic potatoes now contain a proportion of amylopectin of as much as 100%, enabling the energy-consuming separation to be dispensed with. The starch obtained from these potatoes is suited not only for use in the technical industrial sector, but also as a binding agent and thickener in the food industry.
These new grades are already being cultivated on an experimental scale. In the European Union, 97 applications for licences for the release of genetically modified potatoes with a modified carbohydrate metabolism had been lodged up to April 1999. The potatoes involved are ones in which a multitude of modifications have been made, all directed at varying composition of potato starch.

Back to Info Kit main page