Introduction of disease and insect resistance in cultivated grapes
Nearly all cultivated grape varieties, of which several thousand are grown commercially, derive their excellence in fruit quality from the Vitis vinifera grape. Although long considered a single species native to the temperate zone of Middle Asia, the vinifera is more of a complex of several ecospecies. Outlying relict populations also exist in some of the principal river basins of the Mediterranean area, and of the Rhine, Mostar, and Danube valleys. However, the role of these populations in the origin of cultivated forms is questionable.