Cultivation

Grape vines are widely grown, mainly in warm and sunny regions. They represent one of the oldest species of cultured plants. There are about 10 000 grape varieties, although only a few play a role in viniculture.

Utilisation

Foodstuff and constituents:

The grapes are processed to:

• Raisins, currants, and sultanas (these designations provide information on the size of the dried fruits).
• Wine

• Fruit, grape juice

By-products:

• Food colourants (e.g. anthrocyanin, E163) can be produced from the grape skin.

Gene technology: aims of research and development

Agronomic traits

Resistance against pathogens

• Fungal resistance, e.g. against grey mould, powdery and downy mildew. Since 1999 there have been field trials with gene-modified fungal-resistant grape vines in two areas in Germany, the Palatinate (Pfalz) and Franconia (Franken). The trials were planned to last for at least 10 years, and examined mainly the varieties Riesling and Chardonnay, for which it had not been possible previously to breed fungus-resistant vines. The trials were suspended at the beginning of 2005.

• Virus resistance: In Colmar (Alsace/France) grape vines with gene-technologically conferred resistance to fanleaf degeneration are being tested in field trials. This disease is caused by viruses that are transmitted by nematodes.

• Bacterial resistance, also in combination with fungal and virus resistance

Weed control

• Herbicide tolerance

Adaptation to climate and localisation factors

• Increased tolerance to cold, to allow viniculture in colder regions (Canada).

Quality traits

Modified composition of components

• Modified sugar content, colour and grape size

Plant development

• Modified flower and fruit development to increase the harvest

Field trials with GM grape vines