UC Davis Rupert Hargreaves

Rupert Hargreaves of Global Plant Genetics

Global Plant Genetics has signed a deal with University of California, Davis to market two UC Davis-patented nematode-resistant grape rootstocks in Europe.

The rootstocks, GRN1 and GRN3, are resistant to a number of nematodes, including root-knot, which are microscopic, unsegmented roundworms that feed on, and harm, the roots of grapevines.

Nematodes cause damage to plants by stunting root elongation, changing root growth patterns and removing nutrients. And since many countries around the world prohibit the use of soil sterilants to control them, the economic impact of damage from nematodes is growing.

Efforts to find nematode-resistant grape rootstocks began at UC Davis in 1993, when 75 crosses were made, producing 5,000 individual seedlings for assessment.

Evaluation of the results of these crosses began in 1996, with 1,000 seedlings identified — from which the best 100 were advanced to test for nematode resistance.

This work was undertaken by Andy Walker, grape breeder and professor in the Department of Viticulture and Enology, and Howard Ferris, professor in the Department of Entomology and Nematology, both from UC Davis.

GRN1 was found to be the most nematode resistant of all the rootstocks tested. It offers resistance to root-knot, dagger, citrus, lesion and ring nematodes as well as phylloxera, a tiny aphid-like insect.

GRN3 has moderate to high vigour and is more likely to do well in lime-based soils. GRN3 is easy to graft and more adaptable to colder climates. It offers resistance to root-knot, dagger, citrus, lesion and phylloxera, but not ring nematodes.

“We are pleased to be working with Global Plant Genetics as our licensee in the EU to commercialise these rootstock varieties,” said Dushyant Pathak, associate vice chancellor of research and executive director of Venture Catalyst at UC Davis.

“The novel properties of the rootstocks developed by professors Walker and Ferris are expected to support the environmentally and economically sustainable production of grapes within the European context.”

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