An ongoing study of seed-priming agents is homing in on how bacteria applied to soybean seeds can improve the plants’ response to disease and drought stress.

LSU AgCenter plant pathologist Jong Ham and his research team have been investigating how different biostimulants or bacterial agents used as seed treatments can help plants fight off stress.

“We observed that plants grown from the treated seeds actually respond faster and in a more robust way to a pathogen attack,” Ham said, explaining that the treatment acts as a kind of immunization, preparing the plant to induce a defense.

The researcher is working to understand the mechanics behind how the bacteria is offering these protections. Ham said it could be epigenetics — how the plant memorizes the stress put on the seed from the bacteria, and upon the real challenge in the field, it can respond more efficiently.

He also suggested that the bacteria may colonize the plant and protect the plant’s roots from drought stress for example. He said an extracellular polysaccharide may act as a coating on the roots.

His research is also looking at characterizing the microbial community in the soil and the seed treatment’s influence on it.

“In the soil, there’s millions of different species or microorganisms living in there, and there are dynamics within the soil,” he said.

LSU AgCenter plant pathologist Jong Ham examines soybean plants in a greenhouse at the Doyle Chambers Central Reseach Station in Baton Rouge. The plants are grown from seeds treated with bacteria that can improve the plants’ response to disease and drought stress. Photo by Tobie Blanchard

Last year, he and his team collected samples from drought-damaged plants in the field and characterized the bacterial composition there.

“We wanted to find some major differences between the surviving plants and the dead or damaged plants,” he said. “We saw some difference in the microbial community in that field, and we isolated some candidate bacterial agents that have some drought tolerance.”

His studies last year were conducted at the Doyle Chambers Central Research Station in Baton Rouge and the Red River Research Station in Bossier City. This year his work continues in Baton Rouge, and he is also working at the Dean Lee Research and Extension Center in Alexandria.

Ham also is working on potential ways to keep the bacteria on the seed stable. He said currently treated soybean seeds should be planted within a week of being treated.

This type of treatment could reduce the need to spray fungicide on the fields.

Ham said the next steps in the project include expanding its scope. He wants to apply the same techniques and technologies to see if the seed-priming agents can affect the plants’ tolerance to nematode damage.

He also plans to analyze the plant’s metabolic changes that result from seed-priming using cutting-edge analytical tools, such as mass spectrometry. Ham said this will help his research team understand the biochemical mechanism underlying the effects of seed-priming.