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New early detection method for ring rot in potatoes explained

April 30, 2009  By Myron Love

Bacterial ring rot has caused havoc in potato fields throughout North America over the years.

Bacterial ring rot has caused havoc in potato fields throughout North America over the years.

“We have just barely escaped a (ring rot-created) nuclear meltdown in the Dakotas over the past two years,” said Dr. Neil Gudmestad, a professor of plant pathology at North Dakota State University with more than 30 years of experience doing research on potato diseases.


Ring rot is not easily detected, Dr. Gudmestad noted. The bacteria can survive on equipment and in storage facilities for a very long time. And only one or two potatoes in a field may show any symptoms.

In the 1980s, immunofluorescence and ELISA tests were the industry standards for detecting bacterial ring rot. In the 1990s, Dallice Mills of Oregon State University introduced genetic screening using polymerase chain reaction (PCR) to detect the DNA of ring rot bacteria.

“We have developed a better mousetrap,” said Dr. Gudmestad. “We have developed a PCR detection method that can detect ring rot in real time and produce results in minutes.”

Building on the work of a Finnish team that took the DNA sequence and developed a knockout gene that makes ring rot non-virulent, Dr. Gudmestad and his team of researchers focused their studies on the cellulase A gene on the plasmid and cellulase B gene. They took some of the gene sequence from cellulase A and B for their PCR.

They then compared their detection method to the ELISA and original PCR testing methods.

“We tested 4,000 tubers in 20 sublots,” said Dr. Gudmestad. “We also infected some of our seed lots.

“Our method of detection was noticeably more effective,” he said, supporting his assertions with a selection of statistical charts showing the test results.
“Bacterial ring rot is not going to go away any time soon,” he said. “We are suggesting that our technology will help detect the disease at a much earlier stage than anything else out there and allow growers to take action that much sooner to save their crops.”

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