New RNA Technology Could Protect Kentucky Sassafras Trees

By Blake Jackson

A fast-moving fungal disease known as laurel wilt is putting sassafras trees at risk in Kentucky, while also threatening other members of the laurel family across the United States.

Researchers at the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment are investigating an innovative biological approach that could help control the disease without broadly affecting other organisms.

The team is studying RNA interference (RNAi), a natural biological process that can shut down specific genes. Researchers develop double-stranded RNA molecules designed to match genes that are essential to a targeted fungus or pest.

Once introduced, the organism’s natural defenses recognize the RNA and can destroy the matching genetic instructions, disrupting critical processes such as growth, nutrition and reproduction.

“It’s like attacking a computer hacker with their own antivirus software,” said Ellen Crocker, Ph.D., associate professor of forest health Extension in the UK Department of Forestry and Natural Resources. “You’re turning that system against itself.”

The researchers hope to create treatments that affect only the fungus responsible for a particular disease.

“The idea is to choose gene sequences that are only in the fungus we want to target,” said Josh Konkol, Ph.D., a UK postdoctoral researcher on the project. “Ideally, you could apply it around other fungi and organisms, and the only one affected would be the pathogen carrying that matching sequence.”

Unlike many conventional fungicides, RNAi could potentially provide highly targeted control while protecting beneficial fungi. The approach can also be developed from a pathogen’s genome and applied externally, eliminating the need to genetically modify trees.

Laurel wilt can kill a sassafras tree within weeks, and treatment options after infection remain limited. Existing fungicides may provide temporary protection but often require expensive, repeated applications that are difficult to use across forests.

“For sassafras, the future situation is pretty bleak if we don’t have better tools,” Crocker said. “The exciting part of RNAi is the possibility of making something extremely targeted to the fungus we want to stop without harming everything else around it.”

The $411,000 USDA Forest Service-supported project also examines RNAi strategies for chestnut blight, Dutch elm disease, butternut canker, emerald ash borer and invasive adelgids.

Photo Credit: ellen-crocker