“Fingerprinting” Helps Make Great Grapes

At about this time next year, nearly all of the 2,800 wild, rare and domesticated grapes in a unique northern California genebank will have had their "genetic profile" or “fingerprint” taken. These fingerprints may help grape breeders pinpoint plants in the collection that have unusual traits--ones that might appeal to shoppers in tomorrow's supermarkets. Other grapes might be ideal for scientists who are doing basic research.

That’s according to Agricultural Research Service (ARS) plant geneticist Mallikarjuna Aradhya. He's heading the grape fingerprinting venture.

The grape collection that Aradhya is fingerprinting encompasses vineyards and screened enclosures, called “screenhouses." It is part of what’s officially known as the ARS National Clonal Germplasm Repository for Tree Fruit and Nut Crops and Grapes, in Davis, Calif.

To glean a distinctive genetic fingerprint of each member of the collection, Aradhya uses pieces of genetic material--or DNA--known as microsatellite markers. Eight markers are all that are needed for a genetic fingerprint of more familiar grapes, like close relatives of those already used for making wine or raisins or for eating out-of-hand.

But the lesser-known ones--wild grapes and some prized types from China, for instance--require twice as many markers for reliable identification. That’s due, in part, to the fact that the taxonomy, or relatedness of one kind of grape to another, is quite jumbled, Aradhya noted.

He has already fingerprinted 1,100 better-known grapes and 300 wild specimens.

ARS is a scientific research agency of the U.S. Department of Agriculture.