Fighting Pathogens: A New Test to Save Crops

By Rita Waimer

Every year, viruses kill millions of dollars of crops in Florida alone. Add to that the other tropical and subtropical regions of the world where these viruses spread and you see that they’re an immense problem, especially in areas where vegetables are essential to people’s livelihood.

Many of these viruses belong to the genus Begomovirus, which infects a wide range of dicotyledonous plants, including crops like tomatoes, beans, squash and cotton. Growers must treat plants infected with these viruses and manage the outbreak as quickly as possible to minimize losses, as an unchecked outbreak could substantially reduce plant yields. Even if a grower notices viral symptoms early, it takes time to run tests and then manage the outbreak.

Finding the Virus

A pathogen cannot be identified by its symptoms because many pathogens cause the same symptoms. They may give the grower an idea of what’s wrong, but testing is the only way to be sure. For that, a sample from an infected plant must be sent to a lab.

Because viruses can’t be cultured like a fungus or bacteria, the lab has to run a polymerase chain reaction. However, many labs don’t run those tests because they’re expensive and time consuming. Even if they do run the tests, answers aren’t guaranteed: assays exist for only a fraction of the 1,600 known plant viruses. Many growers are left with inconclusive or inaccurate results and a field of dying crops — a hefty expense.

A Better Way

Thankfully, it looks like those slow, expensive and possibly ineffective tests are about to be replaced: Jane Polston revealed in the Virology Journal that recombinase polymerase amplification can identify the cause of a disease faster and cheaper than PCR tests. Working at the University of Florida Institute of Food and Agricultural Sciences, she and her colleagues modified the test to check for viruses transmitted by whiteflies in Florida. Their new test makes it easier for labs to identify viruses in plants and crops, giving growers a better chance to save their crops and avoid losses. The UF/IFAS Plant Diagnostic Center officially adopted the new test in the summer of 2016 to benefit Florida’s growers, and Polston and her team hope that other clinics will follow suit and use the test to better equip themselves to diagnose plant viruses.