Agricultural Research Service scientists have made an important genetic discovery that, in addition to unlocking secrets about why grapes are different colors, may allow for more efficient breeding of color-specific grapes.

Color is perhaps the most important of grape characteristics, a critical component of table, juice and wine grapes that's also been linked to antioxidant content.

Plant geneticist Christopher Owens of ARS' new Grape Genetics Research Unit in Geneva, N.Y., and collaborators at France's National Institute of Agricultural Research in Montpellier found that much of the color variety in modern grape cultivars can be traced to variations in a gene recently found to be a causative factor in white grapes' lack of color.

The variations in this gene, which is called VvmybA1, are caused, in part, by movement of Gret1, a genetic mutation within it, according to Owens.

He explained that Gret1 is a type of element that's also known as a type of "jumping gene" because it's a piece of DNA that moves around within a genome. Owens found that Gret1's movements slightly alter the surrounding DNA. These alterations create additional variations in VvmybA1, which in turn influence the grape's fruit color.

The finding is a potential milestone in grape research and production that may one day lead to breeding for color-specific grapes as well as for grapes that can enhance the stability of wines and juice, according to Owens. It may also spur better understanding of relationships between fruit color and health-imparting compounds, as well as the effects of environment and management practices on grape color and quality.

The research may even lead to the development of grapes with novel colors.

Owens' work expanded on independent 2004 research in Japan that identified Gret1 and showed that its interaction with VvmybA1, which is found in all Vitis vinifera grapes, causes white grapes' color.

Read more about this research in the April 2006 issue of Agricultural Research magazine, available online at:

http://www.ars.usda.gov/is/AR/archive/apr06/lakes0406.htm