Norton Grape Hybrid Could Combat Mildew

Missouri scientists seek to hybridize state grape and vinifera to reduce the use of sulfur

by Jane Firstenfeld
Norton mildew
In Missouri State University's Mountain Grove vineyard, rows of Norton and Cabernet Sauvignon grapes were planted side by side. This September, Norton's superior resistance to mildew was apparent. The Norton berries (left) looked perfect, while the Cabernet cluster was riddled with harvest rot complex. Photos: Wenping Qiu.
Columbia, Mo.—Missouri’s official grape may hold the key to resisting common fungal disorders in winegrapes. Norton (also known as Cynthiana) is the state’s signature winegrape, but its origins remain murky to genetic scientists. Norton is now known, however, to possess properties that resist downy and powdery mildew, and viral infections that routinely plague grapes in continental climates like that of Missouri.

Dr. Walter Gassmann, a plant biologist at the University of Missouri in Columbia, is collaborating with Dr. Wenping Qiu, professor and director of the Center for Grapevine Biotechnology at Missouri State University, to create a Norton/vinifera hybrid grape that will both combine Norton’s inborn resistance to native pests with the popular wine attributes of vinifera grapes and reduce the need for sulfur and other fungicides.

Norton, Gassmann explained, is most likely an accidental hybrid of native North American grapes. It’s probably, he said, an ancient hybrid of Vitis aestivalis. “You might find aestivalis vines growing wild along rural roads,” he said, “but they would not give you berries you’d want to consider” for winemaking.

“What’s special about Norton,” he said, “is that although a considerable percentage of its genome is from wild vines, you can make wine from it.” The wild vines provide it with its disease-resistant properties; its wine-worthy characteristics make it a worthy match with its noble vinifera cousins.

Gassmann, a plant biologist who earned his postgraduate credentials at University of California, Berkeley, told Wines & Vines, “I want to understand why Norton can do what it’s doing” in terms of disease-resistance. He explained that the Norton genome has not yet been sequenced, but that now, “DNA sequencing technology has become so cheap you don’t need an international consortium” to perform it.

Supported by a special grant from the United States Department of Agriculture, Gassmann and Qiu expect to continue their research for several more years.

Qiu told Wines & Vines he’d first made a cross between Norton and Cabernet Sauvignon five years ago. “We’ve been evaluating its progenies for the past three years. We plan to select a few to do another round for evaluation for disease resistance, viticultural properties, and then three years later, for wine quality,” he said. 

The first Norton/Cabernet Sauvignon hybrid was planted in 2007. Qiu and colleagues tasted the first grapes this year. “They tasted like a hybrid Norton/Cabernet Sauvignon,” he reported. “We’re a few years away” from the ultimate result, he acknowledged.

Arriving in Missouri in 2000 as a plant pathologist, Qiu recalled, “I wanted to study why plants have the capacity of resisting disease. Norton has an extremely high rate of tolerance. I was fascinated by its traits.”

Gassmann commented, “It’s not trivial to make good wine out of Norton. It makes more secondary metabolites than vinifera. It’s trying to defend itself.”

Much of Gassmann’s initial research has involved transgenic experiments using a fast-growing mustard-like plan, Arabidopsis, which has a gene similar to the targeted fungus-resistant grape gene. Propagating hybrid grapevines is a long-term process.

Gassmann commented, “It would be so much easier to make transgenic vines.”
Currently no comments posted for this article.