Groundbreaking discovery links plant resilience to a microbial balance
Researchers from the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) and the National University of Singapore (NUS) have uncovered a surprising strategy by which plants thrive when a key nutrient—sulphur—is in short supply. In a study published in Cell Host & Microbe on September 26, 2025, the team shows that soil microbes, competing in the rhizosphere—the soil zone around plant roots—release a well-known compound called glutathione. This chemical acts to enhance plant growth under sulphur-deficient conditions, but not without a cost: the same microbial players that aid the plant see a reduction in their own growth. The scientists describe this as a “trans-kingdom fitness trade-off,” a balancing act where one kingdom of life assists another at a microbial expense.
Why sulphur matters for plants and the global farming system
Sulphur is essential for plant growth, supporting protein synthesis, vitamin development, and stress resilience—paralleling the roles of nitrogen and phosphorus. Historically, atmospheric sulphur pollution replenished soils. Tightened air-quality rules and cleaner energy sources have reduced these natural deposits, leading to sulphur-deficient soils in many agricultural areas. Farmers have turned to sulphur-based fertilisers as a stopgap, but this approach raises concerns about runoff, waterway eutrophication, and broader environmental degradation. The new study offers a long-term, nature-based alternative path to sustaining crop yields in the face of nutrient stress.
The trans-kingdom fitness trade-off: mechanism and implications
In the rhizosphere, competing bacteria release glutathione, a molecule traditionally associated with cellular redox balance. The researchers demonstrated that this glutathione directly benefits plant health under low-sulphur conditions, effectively boosting plant fitness. However, the microbial community experiences a slowdown in growth as a consequence of this alliance. This elegantly simple yet powerful finding reveals a trans-kingdom fitness trade-off: microbes sacrifice some of their competitive edge to support the plant, forging a collaborative holobiont that adapts to nutrient stress.
From mechanism to field-ready solutions
Lead author Arijit Mukherjee, a former PhD student at SCELSE and the NUS Department of Biological Sciences, emphasizes that plant fitness is a property of the broader plant–microbe community. “Plant fitness isn’t just about the plant itself—it’s about the whole community of microbes around it,” he notes. The discovery provides a mechanistic blueprint for developing microbial consortia or “cocktails” that naturally bolster crops under nutrient stress, reducing reliance on chemical fertilisers and improving soil health. Assoc Prof Sanjay Swarup, SCELSE Principal Investigator and Deputy Director for NUS Environmental Research Institute (NERI), describes the work as a stepping stone toward sustainable agriculture that can help secure global food supplies while protecting ecosystems.
Towards sustainable agriculture and better food security
The research points to a practical, scalable path: design microbial communities that cooperate with plants under sulphur limitation, delivering resilience without escalating chemical inputs. By leveraging natural plant–microbe partnerships, farmers could maintain or even improve yields in sulphur-poor soils while curbing environmental impacts. The study’s implications extend beyond a single nutrient; trans-kingdom interactions may be a common strategy in host–microbe systems, enabling holobionts to adapt to fluctuating environmental cues.
From discovery to patent protection and real-world products
To move from bench to field, the team has filed a patent covering applications of this plant–microbe mechanism in agriculture. The patent aims to pave the way for bio-based products that support crops in sulphur-deficient soils, ultimately reducing chemical inputs and promoting resilient farming systems. “By considering not only microbial functions but also their interactions, we can design more effective microbial consortia for agriculture,” adds Assoc Prof Swarup. This approach aligns with a climate-ready agricultural paradigm that balances productivity with ecological stewardship.
A broader scientific and societal impact
The trans-kingdom fitness trade-off concept may be widespread across host–microbe systems, offering a new lens to understand how holobionts adapt to environmental pressures. As researchers continue to unravel these interactions, the prospect of nature-informed solutions for sustainable farming grows more tangible—promising healthier soils, less pollution, and stronger global food security.
