Ancient Plant Partnerships: Conserved Symbiotic Signalling and Its Role in Sustainable Agriculture
A team of researchers from the University of Toulouse, a partner institution in the Enabling Nutrient Symbioses in Agriculture (ENSA) project, has uncovered significant insights into the genetic pathways that enable plants to form symbiotic relationships with fungi. The study, led by Pierre-Marc Delaux with Tatiana Vernié as the lead author—both members of ENSA—reveals that these pathways, essential for nutrient exchange, have been conserved for 450 million years. Published in PNAS, this research not only enhances our understanding of plant evolution but also supports ENSA’s goal of developing sustainable agricultural solutions through improved nutrient uptake in crops.
The Common Symbiotic Pathway
The study centres on the Common Symbiotic Pathway (CSP), a set of genes essential for arbuscular mycorrhizal symbiosis (AMS). AMS is a mutualistic relationship in which plants and fungi exchange nutrients, enabling plant growth in nutrient-poor soils. Using the liverwort Marchantia paleacea as a model organism, the researchers identified three key genes—SYMRK, CCaMK, and CYCLOPS—that are indispensable for AMS in both flowering plants and non-vascular plants, two lineages that diverged 450 million years ago.
Connecting Ancient Symbiosis to Modern Agriculture
The conservation of the CSP across all land plants suggests that this pathway has been critical to plant survival and adaptation since the colonisation of land 450 million years ago. These findings provide a valuable framework for ENSA, which focuses on enhancing naturally occurring nutrient symbioses in agriculture. By understanding how this ancient signalling mechanism functions, researchers can explore ways to make modern crops more efficient at nutrient acquisition, reducing dependence on chemical fertilisers and improving agricultural sustainability.
Insights From plant evolution
Using Marchantia paleacea, the team investigated the role of the CSP in a plant lineage that diverged early in evolutionary history from the lineage that led to the flowering plants. They found that disrupting any of the three core genes completely abolished the plant’s ability to form symbiotic relationships with arbuscular mycorrhizal fungi, while overexpression of these genes activated transcriptional programmes associated with AMS.
This comparative approach, studying bryophytes alongside flowering plants, allowed the researchers to trace the conservation and refinement of symbiotic mechanisms over hundreds of millions of years. This perspective not only highlights the resilience of the CSP but also its potential to adapt to different plant species.
A Step Forward for ENSA
This work aligns closely with ENSA’s mission to harness the natural processes of nutrient symbiosis for sustainable agricultural development. By leveraging the deep evolutionary conservation of AMS-related pathways, scientists can investigate ways to optimise these processes in staple crops. This could lead to more sustainable farming practices, particularly for smallholder farmers in sub-Saharan Africa, where ENSA aims to address challenges in soil fertility and food security.
The study led by Pierre-Marc Delaux exemplifies how combining evolutionary biology with applied agricultural research can address global challenges. For more information about ENSA’s mission and ongoing projects, visit ensa.ac.uk.
T. Vernié, M. Rich, T. Pellen, E. Teyssier, V. Garrigues, L. Chauderon, L. Medioni, F. van Beveren, C. Libourel, J. Keller, C. Girou, C. Lefort, A. Le Ru, Y. Martinez, D. Reinhardt, K. Kodama, S. Shimazaki, P. Morel, J. Kyozuka, M. Mbengue, M. Vandenbussche, & P. Delaux, Conservation of symbiotic signaling since the most recent common ancestor of land plants, Proc. Natl. Acad. Sci. U.S.A. 122 (1) e2408539121, https://doi.org/10.1073/pnas.2408539121 (2025).