Graduate student Sunira Marahatta in a field where dsRNA treatments are applied to soybean crops. Photo by Anthony Bailey

Soybean farmers use fungicides every year to protect their crops from diseases like soybean rust or leaf blight that damage their crops or yield. While these chemicals are effective, they can also cause harm to the surrounding environment and be cost inefficient.

To rectify this, researchers have been studying how to use genetic information to repel fungi and other pathogens from infecting soybean crops. Using double-stranded RNA, or dsRNA, scientists have discovered a way to suppress the growth of the fungal pathogens that use the identical RNA as their genetic code.

At the LSU AgCenter over the past year, researchers including Zhi-Yuan Chen have investigated different nanoparticles to coat the dsRNA to make it not only more effective as an alternative to fungicides, but even more cost efficient. Chen has also tested using adjuvants with dsRNA, or chemical additives that are used to help keep dsRNA on the leaf during unfavorable weather conditions.

These adjuvants could also help with reaching a layer within a leaf that would more adequately suppress the pathogens beyond just on the surface where the dsRNA is applied.

“We are testing and trying to use certain organic compounds that can weaken the wax layer on the soybean leaves so they allow them to penetrate into the leaves better,” Chen said.

The dsRNA is only useful if it can interact with the pathogen it protects against, but if that pathogen gets inside the leaf, dsRNA on the waxy surface will have less of an effect.

“So, once they get into the inside of the leaves, you still have something there to slow the disease development. That way control can last longer, and less damage will be done to the leaves,” Chen said.

Chen has also continued researching the impacts of adjuvants in extending the duration of dsRNA remaining on the leaf surface. Chen hopes to find a way to keep the dsRNA active and impactful on the leaf, while remaining a cheap and viable alternative.

“We started from last year testing adjuvants,” Chen said. “If the dsRNA doesn’t stick to the leaf surface as tight as it should be when the rain comes, it will be washed off. So, we try to incorporate organic, oil-based adjuvants to make them stick to the leaf surface better.”