Corn Root Bacteria Act Completely Differently Outside the Lab, Study Finds

A new study from North Carolina State University shows that corn-root bacteria behave in starkly different ways depending on whether they are grown in a lab dish or on a living plant, with thousands of their proteins changing once they reach the root. The findings, published in the journal mSystems, underscore that laboratory conditions alone cannot capture how microbes actually behave in nature.

Researchers grew seven corn root bacteria both in vitro, in a lab setting, and in planta, directly on the plant, to compare their behavior. Every bacterium acted differently once placed on the root, though the specifics varied by species. Some became more motile, switching on functions that help them move and swim, while others attached themselves to the root and became far more stationary. On the plant, the bacteria showed a range of behaviors, including activating various secretion systems, solubilizing phosphate and consuming different types of sugar.

"Comparing the microbe growing on the plant to outside the plant, the most mind-blowing thing was that these microbes completely changed their programming," said Manuel Kleiner, an associate professor of plant and microbial biology at NC State and the study's principal investigator. "It's not just 10 or so genes, it's thousands that completely shift as soon as they start interacting with the plant."

The seven bacteria came from what scientists call a defined community, a set of microbes with known genomes that colonize consistently and were confirmed to originate from corn roots, making them reliable subjects for both lab and plant testing. First author Anna Garrell, a postdoctoral researcher at NC State, said further work on how multiple such microbes interact on a host plant could help in developing products for sustainable agriculture.