A new type of nanoparticle could aid in protecting soybean seeds from fungal pathogens. Cristina Sabliov, LSU AgCenter researcher and professor in the Department of Biological and Agricultural Engineering, is working on a new nanodelivery system using lignin particles for soybean seed treatment.

Sabliov and her team of researchers have worked with nanoparticles as carriers of agricultural chemicals. This is the first time they have used lignin, a byproduct of the paper industry, to create the particles.

“We are looking at ways to add value to lignin. It’s biodegradable, and it’s natural,” Sabliov said.

Sabliov has used zein, a protein derived from corn, to create particles in the past. She said lignin nanoparticles are more stable in various levels of soil pH.

Given the seedling diseases encountered by Louisiana soybean growers, Sabliov has proposed that fungicides entrapped in nanoparticles can be formulated into a coating able to protect seeds from fungal diseases during storage and the period immediately after seeding.

Nanodelivery of agrichemicals is advantageous over conventional applications, Sabliov said, and using lignin adds more benefits.

“We are checking a lot of boxes. We use a waste product and add value to it,” she said. “We developed a delivery system that is very targeted. It’s biodegradable. It controls the release of the antifungal, so it’s efficient and it doesn’t affect the environment.”

As the seedling forms, these particles disintegrate in the soil, meaning they have less environmental impact than other products, she said.

Sabliov’s team includes biological and agricultural engineer Carlos Astete, entomologist Jeff Davis and plant pathologists Trey Price and Vinson Doyle. They are in the second year of the four-year project and spent the first year engineering the particles.

The researchers took a polymer called poly(lactic-co-glycolic) acid and covalently attached it to lignin. The new polymer was used to make nanoparticles. Sabliov said the lignin stays on the surface; the core is PLGA.

“That core is critical because it is hydrophobic and acts as a reservoir for the fungicide,” she said. “You want the formulation to protect that seed from fungus attack during storage and also after planting, but you don’t want it to affect the health of the plant.”

This year they are testing the impact of nanoparticle seed treatment on soybean health and insect susceptibility, though COVID-19 has delayed some of the research. Sabliov said plant health will be assessed by measuring plant biomass; root and stem lengths; water and nutrient absorption; and chlorophyll concentration. Plants will be tested for changes in insect susceptibility.

“We will challenge the plant with a fungus, and then we will see if our treatment protects the seed,” she said.

Sabliov’s plan in the next two years is to determine if nanoparticles with entrapped fungicides improve seedling disease control, plant stands, vigor and yield. The treated seed will be sown in hydroponic and sterilized growth media inoculated with Rhizoctonia solani, a common soybean pathogen, to assess whether the treatment will protect the plant. Plants will be monitored for differences in disease incidence and severity.

This story is featured in the Louisiana Soybean and Grain Research and Promotion Board 2020 Report.

In a study, soybean seeds were treated with lignin nanoparticles (LNPs) labeled with fluorescein isothiocyanate (FITC) in order to determine the biodistribution of the particles within nanoparticle-treated seeds before and after one day of germination. Image provided by Eban Hanna