Ancient fungus unlocks secret support system in major food crops that could transform farming practices
Major agricultural crops like oilseed rape, cabbage, and kale may actually be able to tap into a natural subterranean support system to dramatically boost sustainability, following a discovery that overturns a century-old rule of plant biology.
Arabidopsis thaliana, a small flowering mustard plant used worldwide as the primary genetic model in plant biology, was long believed incapable of forming relationships with underground fungal networks. New research published in Current Biology led by Professor Katie Field and funded by a Royal Society Faraday Discovery Fellowship demonstrates for the first time that it can establish a fully functional, resource-sharing partnership with an ancient soil fungus known as a Mucoromycotina fine root endophyte (MFRE).
For decades, it has been understood that members of the mustard family (Brassicaceae) are unable to form symbiotic relationships with fungi. Millions of years ago, the loss of vital genes stripped these plants of essential components of the Common Symbiosis Signalling Pathway (CSSP) - the genetic lock-and-key mechanism land plants typically use to pair with beneficial soil fungi.
Previous attempts to force fungal partnerships were largely unsuccessful so scientists concluded this natural network was permanently closed off to an entire family of major food crops. However, because MFREs belong to a different lineage of fungi that diverged 620 million years ago, they bypass the conventional CSSP signalling route, unlocking a completely unique mechanism for plant-microbe communication.
This discovery is incredibly exciting because it challenges one of the long-standing assumptions in plant biology. We’ve found that a fungus can form a functional, mutually beneficial partnership with a plant thought to be incapable of such relationships, and the evidence suggests it does so in a fundamentally different way from the fungi we know best. It opens up a whole new avenue of research into how plants and fungi communicate and exchange resources, and raises the tantalising possibility that we’ve been overlooking an important source of natural support for plants, including some of our most important crops.”
Professor Katie Field
Using advanced cell imaging and multi-isotope tracing, the team discovered that a wild strain of fine root endophyte (isolate Lyc-1) extensively colonised Arabidopsis roots without affecting plant growth or causing disease. Tests revealed a robust two-way trade: the fungal network absorbed nitrogen and phosphorus from the surrounding soil and transferred them directly into plant shoots, while receiving over 260 per cent more plant-fixed carbon in return.
“We already have a good understanding of Arabidopsis genetics, development and interactions with pathogens. This latest work from the Field lab makes the Arabidopsis–MFRE interaction an ideal model system for discovering how plants establish this alternative symbiosis. In other words: we can now use this model to rapidly identify the molecular mechanisms driving this ancient partnership and explore how this knowledge could be applied to crops. Ultimately, taking this symbiosis from the lab to the field could offer a nature-based way to improve crop nutrition and resilience, supporting soil health and regenerative farming while reducing reliance on expensive chemical fertilisers.” Professor Jurriaan Ton