Within the soil, a group of unique microbes are working overtime to shield wild plants from salt stress. Now researchers have shown that those naturally-occurring microbes can be successfully transferred to a range of crops and, crucially, can boost their growth.
The obliging microbe, a type of bacteria called Pseudomonas, was identified lurking around the roots of plants exposed to high salt levels, a situation expected to grow worse as climate change causes rising sea levels that push salty water further inland from the coast.
Researchers on a new Science Advances paper observed that while other bacterial colonies died off under salty conditions, Pseudomonas microbes continued to thrive around the roots of wild soybean plants. They think this is because the bacteria contain specialized genes, and it suggests that the microbes hold a competitive advantage under salty conditions.
On a hunch, they isolated samples of these resilient specimens and set about testing how well they did in other crops.
They found that when they inoculated the roots of several crops with these bacteria, the microbes thrived almost universally. Particularly around salt-stressed sorghum, maize, tomato and rapeseed, Pseudomonas populations grew significantly, increasing from 22% to 41%, compared to just 1% to 21% in the control experiments. They weren’t a good match for every crop: populations of Pseudomonas did not flourish around rice and wheat plants, for example.
Recalling the abundance of this microbe around wild soybean plants, the researchers then focused on what it could do for the economically-important and widespread domesticated soybean.
They found that not only did the bacteria swiftly colonize soybean roots—their numbers rising twofold under salt stress—but compared to controls the inoculated soybeans also experienced a significant growth boost under salty conditions, developing considerably longer roots and also forming more lateral ones. The soybeans showed increased salt tolerance in greenhouse experiments, and in open field experiments too.
The question is how the microscopic soil residents seemed to be facilitating this remarkable resilience in plants, something the researchers still don’t have a full answer to. But further investigation gave them some clues—particularly as they noticed that lignin levels in the cell walls of inoculated soybeans increased by between 30 and 35% under salt stress, compared to non-inoculated plants.
Lignin is an ingredient that increases stability and support in plant tissues, and the researchers theorize that something about the Pseudomonas microbes triggers enhanced lignin synthesis in plants, which shields them against rising salt.
Next steps are to uncover precisely how the microbes do this. With that information in place, these bacteria may become a tiny but crucial key to future crop survival, the researchers say. “If scientists can harness this natural process, it could mark the beginning of a new era in climate-resilient agriculture.”
Zheng et. al. “Pseudomonads associated to salt-stressed plantsfacilitate stress adaption of soybean through enhancedlignin biosynthesis.” Science Advances. 2026.
Image: ©Anthropocene Magazine
