Molecular genetics ready to launch a golden age of winegrape breeding

Growing winegrapes may be the most backward form of horticulture that exists. The vast majority of the world’s production uses only about 20 cultivars out of thousands of available grape varieties. The wine industry is convinced these traditionally-cultivated varieties alone provide all the diversity necessary and that newly-bred varieties can’t compete on wine quality. This belief persists in the face of modern genetic evidence that many of the world’s traditional varieties were intentionally bred from older ones. But things may start to shift as wineries in highly-recognized regions cope with a changing climate.

Breeding through the centuries

Improvement of the limited set of traditional varieties is done through clonal selection. People watch for natural mutations in vine offshoots called bud-sports. When these mutations are beneficial (better color, berry size, or ripening dates) the new forms – which are clones – are propagated by cuttings and distributed.

But these naturally-occurring mutations don’t provide the range of fruit and wine quality needed to maintain excellence in a changing climate. Varieties do exist outside the 20 usual suspects that would provide better fruit quality under warmer or colder conditions, but they would have to be tested and promoted. New varieties can be bred, but they will need to be selected for multiple traits, which could take decades. It will be faster and more precise to take advantage of advances in molecular genetics to optimize traditional breeding and select for improved quality, better climatic adaptation and better pest and disease resistance.