When microbes cooperate, crops win

The experts were stunned by all the healthy potato plants.

They were growing in a potato disease research nursery in Grand Rapids, Minnesota, that had been established in 1942. After 35 years of potato monoculture, they should have succumbed to microbial infections. Yet they had thrived, with virtually no disease.

“We couldn’t understand why,” says Linda Kinkel, a professor of plant pathology in the University of Minnesota's College of Food, Agricultural and Natural Resource Sciences. “The field always included some potato varieties that were known to be highly susceptible to disease.”

She and her colleagues suspected the answer lay with the microbes in the soil. To find out, they took samples of soil and heated half of them to kill all the microbes in them. The unheated samples retained their resident microbes.  

Next, they added pathogens to all the samples and grew plants in them to test how well they would resist being infected.  

“Only the plants in the unheated pots resisted being infected,” Kinkel says. “So we know that suppression of  the pathogens was because of the naturally occurring soil microbes.”

During subsequent years of experiments, she and her team showed that pathogen suppression was due not to a single beneficial microbe, but to a web of interacting microbes that support plants. In this community, “good” soil microbes co-exist and collaborate; this keeps the “bad” microbes in check. 

Today, Kinkel uses that knowledge to supply farmers with microbes to ward off infections and support plant vigor so their crops can thrive.

The web, untangled 

Many microbes feed on material that leaks out of living plant roots or that is contained in the residues of dead plants. And that’s a lot.

“It’s been established that overall, plants can leak up to 40 percent of the atmospheric carbon they have “fixed” into organic matter via photosynthesis,” Kinkel says. “Microbes compete actively for that food.”

In return, these microbes repackage nutrients like phosphorus, potassium, zinc and iron into forms that a broad spectrum of plants need to grow. Kinkel calls these microbes — which have co-evolved complex partnerships with plants and each other — the “good guys,” in contrast to the pathogenic “bad guys.” 

“The bad guys invest a lot of their resources in being pathogens,” she explains. “They make chemical weapons with which to infect and evade detection from plants, not defenses that allow them to compete for resources against other bacteria or fungi.”

Fortunately, “the good guys are more abundant.”

The good guys invest their energy in evolving, for example, antibiotics to keep rival species from growing too much and getting too much of the food. As their density and the competitive stress rise, so does the evolutionary pressure for developing potent defenses against rival species. But it also opens the door for them to partner with plants and other soil microbes to keep out aggressive pathogens that would destroy their food source: the plants. 

Unfortunately for the pathogens, they have specialized in defeating plant defenses, not antibiotics from resident microbes.

“The bad guys become collateral damage from the interactions among the good guys,” Kinkel says. This amounts to the good guys teaming up on the bad guys. “It takes a village,” she observes.

Changing the paradigm

To help farmers, Kinkel and her colleagues have patented several microbial technologies to add “good guy” microbes to agricultural fields.

“Microbes can help plants emerge earlier and maintain healthier growth throughout the season,” she says. “We want to change the paradigm for microbes in agriculture. Our focus is on moving beyond single, silver-bullet approaches to microbial inoculants to creating dynamic microbial partnerships in the soil.   

“For the farmer, the most important impact is the increase in crop yields and the potential reduction in other inputs, such as fertilizers and pesticides.” 

A revolution that boosts harvests worldwide  

After years of this research, Kinkel got a chance to test her microbial treatment against a commercial product — and her technology came out the clear winner. In 2013 she worked with the University of Minnesota’s Research and Innovation Office to commercialize her work and facilitate the delivery of her microbial technology to farmers. 

Kinkel and technology commercialization experts in the office filed patent applications for the microbial technologies, found an investor to underwrite experiments on a commercial scale, assembled a board of directors, and launched a new startup company: Jord Bioscience, where she is the chief scientific officer. 

“We have field trials across the country and in South America,” Kinkel notes.

Her work has not gone unrecognized. Last fall she became one of 39 pioneers in agriculture and global food security to be named a 2025 Top Agri-Food Pioneer by the World Food Prize Foundation. In its citation, the foundation said, “Her ‘biological playbook’ model has revolutionized product development timelines in the agricultural biologicals sector.”