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DNA system tests for potato pathogens

A new diagnostic system will test for soil-borne threats to potato crops.

July 2, 2014, Australia – Scientists at the South Australian Research and Development Institute (SARDI) have created a diagnostic system that tests for six soil-borne pathogens that threaten potato crops. 

PreDicta Pt was launched commercially last August and has received widespread support from growers, processors and agronomists across Australia.

Potatoes are particularly susceptible to soil-borne disease that can damage their appearance or reduce yield, and field losses are estimated at around $80 million a year across Australia.

The basic technology behind PreDicta Pt is based on a well-established commercial service offered by SARDI for cereal crops called PreDicta B.

“Potatoes are a big investment and you don’t want to get it wrong,” said SARDI sustainable systems research chief Dr. Kathy Ophel Keller.

“Based on what our test tells them, farmers may choose to plant different parts of their land differently and to ignore some completely. If they lease land, it may help them choose between options.

“The next step is to test seed pieces as well so you can match clean seed with clean ground. The last thing you want to do is put dirty seed into clean ground. That’s a real issue with a crop like potatoes.”

Ophel Keller and colleague Dr. Alan McKay began developing their testing regime soon after she joined SARDI (the research arm of Primary Industries and Regions SA) from Australia’s Co-operative Research Centre for Soil and Land Management in 1996.

“We were extracting DNA from soil and using fairly crude hybridisation techniques to measure the pathogens and we quickly realised we need to change the technology pretty radically,” she said.

Working with engineers at the University of South Australia, they developed equipment that was sufficiently robust to test 500-gram soil samples (large enough to deal with spatial variability across a paddock) rather than the 10 grams that is usual for research and, more importantly, could produce clean DNA.

“What we have focused on is how to take a representative sample and, once you've got it, how to extract clean DNA every time and to put the quality systems in place to ensure that that is always the case,” Ophel Keller says.

PreDicta Pt and PreDicta B, which were developed with funding support from Horticulture Australia Ltd and the South Australian Grain Industry Trust and Grains Research & Development Corporation respectively, are offered commercially to farmers through agronomists trained to analyze the findings and help farmers make follow-up decisions.

For more information, contact Dr Kathy Ophel Keller at kathy.ophelkeller@sa.gov.au.

July 21, 2014  By The Lead South Australia