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The scheme of generating and testing rhizosphere microbial inoculants in this study. Soybean cyst nematode (SCN)-susceptible cultivars were Dickey, Rolette, IA2104RA12, IA3054RA12, and Williams 82; SCN-resistant cultivars were ND17-22117, ND17-20565, IAR1903SCN, IAR2801SCN, and Jack. Credit: Phytobiomes Journal (2026). DOI: 10.1094/pbiomes-07-25-0049-r
Soybean cyst nematode (SCN) is among the most damaging pests affecting soybean crops around the world, with current management strategies relying primarily on a very narrow set of resistant soybean varieties, along with crop rotation and chemical nematicides. Now, researchers at the North Central Agricultural Research Laboratory, part of the USDA Agricultural Research Service, in Brookings, South Dakota, report new evidence that the key to stronger protection may lie not just in plant genetics or chemicals but in the soil microorganisms surrounding the roots.
In a new study published in Phytobiomes Journal, Chuntao Yin and Nathan Lahr report that resistant soybean varieties actively recruit beneficial soil microorganisms that help suppress SCN. Even more striking, those protective microbes can be transferred to soil to help defend susceptible soybean plants.
"What excites me is that soybean plants do not combat the soybean cyst nematode on their own," said Dr. Yin. "Plant genetics influence microbial communities by recruiting beneficial microorganisms from the soil that actively contribute to disease suppression."
To better understand the role of soil microbes, the researchers compared the microbial communities surrounding the roots—known as the rhizosphere—of 10 soybean varieties, including five resistant and five susceptible to SCN. Using DNA sequencing, the team identified distinct microbial patterns associated with resistant plants. Certain beneficial microorganisms were consistently more abundant in the rhizosphere of resistant varieties compared to susceptible ones.
The team then tested whether these microbes were actively contributing to nematode suppression. They transferred microbial communities from the rhizosphere of resistant plants into soil in which a susceptible soybean variety was grown. The result: Susceptible plants grown in soil containing microbes from resistant varieties experienced significantly lower SCN infection.
"The significant reduction of SCN populations demonstrated that these microorganisms actively contribute to nematode suppression—not just plant genetics alone," Dr. Yin explained.
The study demonstrates that soybean resistance to SCN is not only genetic but also microbiome-driven. It provides experimental evidence that transferring beneficial microbial communities can reduce infection in vulnerable plants.
"This research suggests that future crop protection may rely not only on chemicals and genetics but also on managing 'good microorganisms' and turning the soil into a natural defense system for plants," said Dr. Yin.
The findings have broad implications for plant pathology, microbiology, soil science, plant breeding, and the future of agriculture. By harnessing beneficial soil microbiomes alongside traditional practices, researchers and farmers may be able to develop more sustainable and resilient strategies to manage one of soybean's most persistent threats.
More information Chuntao Yin et al, Rhizo-Microbiome Engineering for Enhancing Soybean Resistance to Soybean Cyst Nematode, Phytobiomes Journal (2026). DOI: 10.1094/pbiomes-07-25-0049-r
Provided by American Phytopathological Society
— Source: Phys.org (https://phys.org/news/2026-03-soybeans-beneficial-soil-microbes-defend.html)
