A significant research step has been taken in the fight against Asian soybean rust.

A recent research article, "Early Detection of Asian Soybean Rust Using PCR," published in Plant Health Progress, an online, peer- reviewed journal whose scope covers applied plant pathology, entomology, and nematology, demonstrated the reliability of the polymerase chain reaction (PCR) assay in detecting the presence of Asian soybean rust (ASR) within six days of infection, before damaging spores can be generated.

"The entire soybean industry is going to benefit from this study," said James P. Stack, a plant pathology professor at Kansas State University and co-author of the article. "Without using PCR, you have to wait as many as nine days to see the spores. Then a diagnostic must be done before an applicator can be called in to apply a fungicide spray to the soybean field. During that time, the disease is still increasing, and its opportunity to spread increases too. Whatever you can do to shorten the time interval from detection to response, you are minimizing the impact."

The study was conducted in seven laboratories across the United States and involved 17 scientists from the U.S. Department of Agriculture and five U.S. land-grant universities, including the University of Tennessee, Cornell University, Kansas State University, Michigan State University, and the University of Florida.

In a USDA containment facility, soybean plants were inoculated with Asian soybean rust spores. After infection, plant tissue was harvested seven times over 12 days. DNA was then extracted from the harvested tissue and tested for the presence of ASR using conventional and real-time PCR assays at each lab. Across these seven labs, ASR was consistently detected six days after inoculation.

The study demonstrated the PCR assay's ability to repeatedly detect Asian soybean rust on soybean plants before the presence of readily visible symptoms.

"This should demonstrate to the user community that the soybean rust PCR assay is reliable and useful for early detection," said Douglas Luster, Research Leader at the United States Department of Agriculture, Agricultural Research Service (USDA-ARS) Foreign Disease-Weed Science Research Unit in Maryland and co-author of the study.

Also of significance, the researchers demonstrated the reproducibility of results using different PCR platforms.

"The results came out on top of each other," said Reid Frederick, a researcher at USDA-ARS, Foreign Disease-Weed Science Research Unit and another co-author of the study. "It was rewarding to see that it is reproducible in different people's hands."

"This is the first step in validating this assay," said Luster. "The next step is testing the assay with real-world samples from soybean field plots."

Plant Health Progress is a publication of the Plant Management Network, a cooperative resource for the applied plant and agricultural sciences. Designed to provide plant science practitioners fast electronic access to proven solutions, the Plant Management Network offers four science-based applied journals, four field trials publications, and an extensive searchable database comprised of thousands of web-based resource pages from the network's partner universities, companies, and associations.