FROM Riesling to Merlot, wine grapes from around the world are more closely related than expected, says the largest study so far to produce a family tree of grapes. The tree, above, also reveals that in 6000 years of domestication, breeders have left a vast vineyard of possible varieties unexplored.
Sean Myles of Stanford University in California and colleagues looked at 9000 genetic markers in each of the world's 583 cultivated grape varieties, or cultivars, to draw up the family tree of wine grapes.
They found that unlike other domesticated crops, most of the main cultivars are close cousins of one another. This was true regardless of where they are grown (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1009363108).
Moreover, breeders have been unimaginative in the crosses they have made, reusing the same cultivars over and over.
The Traminer cultivar, for example, has been bred for millennia and has 20 first-degree relatives. This is good news for breeders seeking to develop cultivars that are resistant to disease, says Myles, as so few of the potential crosses have actually been made.
