Overview: A surprising plant-microbe strategy under nutrient stress
Researchers from the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) and the National University of Singapore (NUS) have uncovered a hidden mechanism by which plants can thrive when soil sulphur is scarce. The team reports that in the rhizosphere—the soil zone surrounding plant roots—microbes vie for nutrients and, in doing so, release a well-known molecule: glutathione. This compound, traditionally associated with cellular protection and redox balance, unexpectedly enhances plant growth under sulphur-deficient conditions. However, this botanical advantage comes at a cost to the microbes themselves, revealing a cross-kingdom balancing act researchers term a “trans-kingdom fitness trade-off.”
What is a trans-kingdom fitness trade-off?
The core finding is that the plant’s improved fitness is achieved through a microbe-mediated mechanism that reduces bacterial growth. In other words, when soil bacteria compete for nutrients, their release of glutathione benefits the plant more than it does the microbes, creating a trade-off between two major biological kingdoms. “Plant fitness isn’t just about the plant itself—it’s about the whole community of microbes around it,” explained Arijit Mukherjee, the study’s first author. This insight reframes plant development as a property of holobionts—the host and its associated microbial community acting together to meet environmental challenges.
Why sulphur matters in agriculture—and why this discovery matters now
Sulphur is essential for protein synthesis, vitamin production and stress resilience in crops. Historically, atmospheric sulphur from industrial emissions replenished soils worldwide. Clean energy policies have since reduced atmospheric sulphur deposition, and many soils have become sulphur-depleted as crops continuously draw it down. Farmers increasingly rely on sulphur fertilisers as a quick fix. While effective in the short term, fertiliser use can contribute to nutrient runoff and broader environmental degradation. The new study offers a nature-based alternative by harnessing microbial interactions that naturally support plant growth under stress.
The science behind the discovery
Published in Cell Host & Microbe on 26 September 2025, the research provides a mechanistic explanation for how microbial competition in the rhizosphere translates into plant advantages. When bacteria compete, they secrete glutathione, which appears to stimulate plant growth and resilience under sulphur scarcity. The trade-off arises because the same microbial activity that benefits the plant reduces the microbes’ own fitness. This cross-kingdom effect highlights an elegant form of cooperation and competition intertwined within the soil ecosystem.
Implications for sustainable agriculture
The discovery opens doors to designing microbial consortia—carefully selected groups of microbes—that bolster crop health without overreliance on chemical fertilisers. Such bio-based solutions could reduce fertiliser use, improve soil health, and contribute to global food security in the face of climate variability. Assoc Prof Sanjay Swarup of SCELSE and NUS emphasizes that this work provides a blueprint for sustainable agriculture by leveraging natural plant-microbe partnerships to protect ecosystems while maintaining yields.
From discovery to application: patents and future directions
To translate these insights into practical tools for farmers, the research team has filed a patent covering applications of this plant-microbe mechanism in agriculture. The goal is to develop bio-based products that support crops in sulphur-deficient soils, reducing dependence on chemical inputs. As Assoc Prof Swarup notes, “By considering not only microbial functions but also their interactions, we can design more effective microbial consortia for agriculture.” The work also aligns with broader aims of climate-ready farming by fostering resilient crop systems through natural partnerships.
Conclusion
The trans-kingdom fitness trade-off uncovered by SCELSE and NUS researchers reframes how we understand plant resilience. By tapping into the intricate dialogue between plants and their microbial partners, scientists are edging closer to sustainable, low-input farming that guards both yields and ecosystems. This research marks a step toward smarter, biology-informed agriculture in a world facing nutrient stress and climate change.
