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Rapid DNA fingerprinting for grapevine varieties
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Researchers at Linnaeus and Riversun Nursery Ltd in Gisborne have developed a faster and more accurate method of verifying grapevine varieties using a DNA testing technique more commonly associated with forensics.
The breakthrough, announced in a report published in BMC Plant Methods will be of major benefit to nurseries and winegrowers because it enables rapid identification of scion and rootstock varieties.
“The article highlights our laboratory’s new methodology,” says John Mackay, a molecular biologist at Linnaeus and the principal author of the paper. “Correct identification is becoming increasingly important as plantings continue into more marginal areas of New Zealand – rootstock choice in particular can play a vital role in vine establishment.”
The need for such testing is also set to rise sharply because the New Zealand Winegrowers Grafted Grapevine Standard requires nurseries to be able to demonstrate their plant materials are true to type.
“Historically, the classification of rootstocks has been dubious both internationally and here in New Zealand,” says Dr Roderick Bonfiglioli, technical director at Riversun and Linnaeus.
The confusion is not surprising, notes Bonfiglioli, given the high genetic similarities between varieties and the length of time that some stocks have been in the country.
“The nursery industry’s record-keeping has not always been robust,” he adds.
While a method of DNA fingerprinting for grapevine scion and rootstock varieties has been in use for several years, the length of time required for each test – and the associated costs – have meant the technique was used mainly for research purposes rather than in the vineyard.
Instead, most winegrowers and nurseries have relied on traditional ampelographic methods, which are costly and involve a specialist’s visual examination of vine characteristics, particularly leaves and shoots.
As with forensic identification at crime scenes, the DNA analysis and certification of grapevine varieties is performed in a similar manner using variable regions of DNA called “microsatellites.” The regions of DNA vary between the different scion and rootstock varieties, and up to six of these regions are analysed to provide a conclusive match for the sample under investigation.
At Linnaeus, the DNA regions of the sample are selectively amplified by PCR (Polymerase Chain Reaction) and then matched with reference samples of the suspected variety.
“We concentrated on rootstocks initially because we knew there were inconsistencies in the records and some growers had expressed their suspicions concerning identification,” says Mackay. “Indeed, these concerns have been proved correct in a number of instances.”
The Linnaeus method has commercial applications beyond viticulture since it can be used for other horticultural crops and plants where “true to type” certification is required.
“The accuracy and the speed of our new test mean that we are able to offer a definitive answer regarding trueness-to-type,” Mackay continues. “Growers want that level of assurance and the Grafted Grapevine Standard requires it.”
The report is available through open-access publishing at http://www.plantmethods.com/content/4/1/8
For more information on the new DNA fingerprinting technique for grapevine varieties, please call John Mackay, Molecular Biologist & Business Development Manager, email;