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Faculty Focus: Joe Polacco

Studying Missouri's wild grapes for genes to improve European varieties

In the mid-19th century, French winemakers watched helplessly as a mysterious illness struck their grape vines. The malady was actually an exotic insect to which their grapes had no natural resistance, and millions of acres of vineyards were destroyed.

Fortunately for the French, native North American grape varieties exhibited the needed resistance. Scientists from Missouri and elsewhere showed how grafting European grape shoots to American rootstocks could provide protection. Soon, millions of rootstocks were shipped to Europe, and the French wine industry was saved.

More than 125 years later, Missouri scientists are again looking to native grapes to improve commercial grape varieties against pest and plague alike.

"Genetic diversity is really the battle cry for the renaissance of Missouri wines," said Joe Polacco, University of Missouri professor of biochemistry. "We're at the center of diversity with a number of native varieties."

Polacco is part a new collaborative research effort studying native grapes. He and scientists at Southwest Missouri State University, Purdue University and the Donald Danforth Plant Science Center in St. Louis are working to identify and characterize grape genes that provide disease resistance and stress tolerance. The group recently earned a two-year grant from the Cooperative State Research Education and Extension Service.

"We want to identify genes in Norton and other Missouri varieties that could provide resistance against fungal pathogens such as downy and powdery mildew and against environmental stresses such as drought or salinity," Polacco said. "Once identified, these genes could be transferred into European grapes."

The genetic base for North American grapes is much larger than European varieties, he explained. "The last ice age wiped out most of them, and the present varieties came from a small pool of survivors. Because of that, Europe's varieties and ours vary considerably with respect to genes for adapting to stress and disease. These differences are extensive, and meaningful, especially when you consider that humans and chimps share more than 99 percent of the same DNA."

The research team will use a number of genetic techniques to design and build tools for scientists worldwide who study grapes.

Part of the project will concentrate on comparing similarities and key differences in the genes of European and North American wild grapes. Another aspect will focus directly on identifying those genes that may confer desired resistance.

"We'll be looking at gene expression, seeing how expression levels in certain genes in our native varieties change as plants are grown under different stresses and growing conditions," Polacco said. "We'll also catalog differences in different tissues, such as the leaves and fruit, and at various growth stages."

Once genes are identified, he said that eventually wild varieties could be selected for crossing with commercial grapes. "There's a lot of technology still being worked out," he said. "We'd eventually like to establish a grape breeding program."

Article by Jason Jenkins, Extension & Agriculture Information

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