Rapid Diagnosis Spots Sick Potatoes

Agricultural Certification Services, Inc. (ACS)

May 06, 2009— Fredericton, New Brunswick

Dr. Mathuresh Singh (Image Courtesy: Agricultural Certification Services Inc.)

When New Brunswick seed potato farmers look out across their fields, they know that there's more than meets the eye out there. Those healthy-seeming spuds could be harbouring a crop-killing virus. But a new DNA-based diagnostic test is leaving nowhere to hide for potato viruses.

Developed with support from the National Research Council of Canada Industrial Research Assistance Program (NRC-IRAP), the new potato virus test in providing potato farmers with the edge they need to meet expanding global markets: certified disease-free seed potatoes.

Seed potatoes are tubers that are grown to a juvenile stage, harvested, and then sold to other farmers as seed stock. New Brunswick's seed potato growers are part of a potato sector that generates approximately $1.3 billion annually.

But the success of the province's increasingly international seed potato business hinges on a key guarantee to buyers: disease-free potatoes. Since seed potatoes are harvested as mature tubers, they can harbour disease that's only evident, and damaging, in the next generation.

Until recently, the only way to test for viral infection of seed potatoes was to actually grow them - a process that takes six to eight weeks. But since seed potato planting periods vary around the globe, seed potatoes must often be shipped immediately after harvest to meet planting times elsewhere, for example in South America.

"The time lag in this testing meant that, in many cases, growers didn't have the virus results before shipping their seed potatoes to international clients," says Dr. Mathuresh Singh, Director of Fredericton-based Agricultural Certification Services, Inc. (ACS).

It was a testing delay that resulted in angry customers, and lost markets, when New Brunswick seed potatoes were found to be infected with a virus only after they'd already been planted.

But now New Brunswick seed potatoes are getting state-of-the-art viral diagnosis - and a clean bill of health - before they're ever put on a truck or boat for export.

With support from NRC-IRAP, ACS has developed a rapid, post-harvest, real-time DNA-based screening and certification process for seed potatoes. ACS is fully owned by Potato growers of New Brunswick and managed by Potatoes New Brunswick, the province's potato growers association.

"Testing that once took up to two months now takes days," says Dr. Singh.

Developed over a three-year period, the heart of the new test is the ability to identify potato-viruses using genetic primers. These are molecules that target distinctive, fingerprint-like regions of viral genes with which the virus can be accurately identified.

Dr. Singh developed primers for six major potato viruses, including potato mosaic virus and potato leafroll virus.

"As a result of this new technology, ACS has become a lab of choice for potato disease testing," says Tim Jackson, NRC-IRAP Industrial Technology Advisor. With a background in the development of DNA-based technologies, Jackson helped develop the ACS research plan.

Now potato farmers send ACS a batch of about 200 seed potatoes, and within days receive a diagnosis as to whether the potatoes have too high a viral load to be sold as seed potatoes. If unsuitable as seed, the spuds can be left in the ground to mature and be used as table or processing potatoes, a fact that in itself is saving farmers millions of dollars annually.

"NRC-IRAP support made this technological advance possible," says Dr. Singh. "The New Brunswick government supported the purchase of our equipment, but we needed NRC-IRAP support to actually develop and optimize the potato virus diagnostic procedures."

With support from the International Science and Technology Partnership Canada Inc., ACS is presently leading a project to share the potato virus diagnostic technology with potato industry counterparts in China. Currently, China doesn't allow the import of soil-grown potatoes, for fear of also importing potato diseases. But the succesful transfer of this technology might provide New Brunswick seed potato farmers with access to the world's largest potato market.

Enquiries: Media relations


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