Symposia

Orchid mycorrhizas are symbioses between mostly basidiomycete fungi and members of the world’s largest plant family, the Orchidaceae. Orchid mycorrhizas have often been considered anomalous associations with little in common with AM and ECM interactions. The discovery that they represent true mutualisms and the ease with which they can be studied has now made them valuable models of mycorrhizal functioning. Orchids exhibit a wide variety of fungal associates and mycorrhizal exchanges, creating an excellent opportunity for examining the dynamics of plant–fungus mutualisms and to explore the drivers of fungal diversity and community composition in plant roots. Laboratory axenic studies also make it possible to examine the molecular physiological control of the association with great precision. The Serendipita fungal partners of orchids are widespread in natural and managed landscapes and may contribute significantly to sustainable agriculture over the coming decades.

Ericoid mycorrhizal fungi (ErMF) are key symbionts of Ericaceae plants, influencing plant nutrition, stress tolerance, and ecosystem function across diverse habitats worldwide. Despite their ecological importance, our understanding of their global diversity, distribution, and ecological roles remains fragmented, limiting comparative studies and synthesis. This symposium will bring together leading ErMF researchers to share recent advances in taxonomy, biogeography, ecology, and biogeochemistry. By fostering interactions and initiating a global research network, this session aims to catalyze long-term collaborations, harmonize research practices, and stimulate integrative studies that advance fundamental knowledge of ErMF ecology and evolution. Participants will gain a comprehensive view of the field, identify knowledge gaps, and lay the groundwork for coordinated global research.

It was originally thought that plants uniquely associate with one of the two main functional types of mycorrhizal fungi — ectomycorrhizal or arbuscular mycorrhizal fungi. However, for more than a century, the occurrence of plants that form dual mycorrhizal associations has been increasingly recognized as a genuine phenomenon in natural environments. Despite numerous lines of evidence from different ecosystems worldwide, the prevalence, functionality, and ecological significance of dual associations remain contested. Several key questions persist, such as: (1) Are dual mycorrhizal associations restricted to particular plant lineages or ecological settings? (2) Do they confer measurable ecological or physiological advantages? (3) What methodological and conceptual criteria are required to reliably identify true dual mycorrhizal states? This symposium aims to bring together researchers to discuss the major open questions in the field and to explore promising future directions.

Across ectomycorrhizal (ECM), arbuscular (AM), ericoid (ERM), and orchid mycorrhizal (OM) systems, population biology has moved from markers and single-locus views to whole-genome and population-genomic perspectives. This shift is revealing cryptic lineages, unexpected recombination patterns, genome plasticity, and fine-scale demography that map onto ecology, host range, and environmental gradients—information now crucial for forest management, restoration, and conservation. This ICOM symposium brings together for the first time several of the world’s leading investigators with a focus on intra-species diversity of mycorrhizal fungi and the unique aspects of their population biology.

Mycorrhizal cooperation fluctuates depending on environmental contexts and biotic interactions, and varies in space and time, often at fine/fast scales. Furthermore, mycorrhizal cooperation can involve mechanisms beyond direct reciprocity, such as network reciprocity and multilevel selection. Similarly, plant, fungal, and symbiotic’ mycorrhizal traits can be non-adaptive, or if adaptive, such adaptations either optimize over time or plastically change each generation. However, historically, many models have assumed that mycorrhizal cooperation only involves direct reciprocity and that mycorrhizal traits only tend to optimize over time. This Symposium re-examines how mycorrhizal cooperation and adaptation have been understood depending on research area, model assumptions, and experimental limitations. Specifically, we advocate for a complex systems perspective where plants and their mycorrhizal symbionts are embedded with trillions of microorganisms, constituting holobionts.

This symposium explores the diversity, ecology, and evolution of mycorrhizal associations across the Southern Hemisphere, highlighting their roles in unique biomes ranging from Australian sclerophyll forests to Patagonian woodlands and African savannas. Speakers will examine how distinct geological histories, climates, and plant lineages shape mycorrhizal communities, and how these symbioses influence ecosystem function, resilience, and responses to environmental change. The symposium will also showcase emerging research methods and regional collaborations aimed at advancing our understanding of mycorrhizal biology in this understudied part of the world.

This symposium focuses on advancing the ongoing discussion of fine root endophyte evolution, diversity, and classification. Participants will explore emerging evidence on the origins and morphological variability of these subtle yet widespread symbioses, examine their ecological roles across plant lineages, and evaluate how new molecular and imaging approaches are reshaping our understanding of their taxonomy. The session will also address current challenges in defining and categorizing these endophytes and outline future directions for developing a clearer, more unified classification framework.

This symposium will explore how advances in molecular phylogenetics, genomics, and microscopy are reshaping long-standing taxonomic concepts, revealing hidden diversity, and prompting revisions to nomenclature and diagnostic criteria. The session will highlight current debates, emerging consensus, and the practical implications of classification changes for ecology, evolution, and applied research. Together, contributors will consider how a more robust and transparent systematics can support clearer communication and stronger integration across mycorrhizal science.

It is now firmly established that mycorrhizal fungi, spreading their hyphae throughout the soil, interact with a diversity of soil microbes and recruit some of them to their hyphae-associated microbiomes (recruitment). Other microbes then inhabit fruitbodies or fungal spores. These microbes could complement the fungi functionally (which is well-established for arbuscular mycorrhizal fungi and organic nutrients), use their hyphae as highways for spreading throughout the soil (movement), protect the hyphae from pathogens and grazers, and potentially also benefit from access to recently dead fungal biomass, thus recycling the resources remaining in soil/fruitbody after the fungal death. This symposium will provide an overview of the different processes and involved prokaryotic and eukaryotic microbes, and remain inclusive of all types of mycorrhizal symbioses, including arbuscular mycorrhiza, ectomycorrhiza, and other mycorrhizal types.

It is becoming increasingly evident that fungi are highly versatile organisms capable of adapting to a wide range of ecological niches. This raises the question of whether the ability to colonize multiple niches is a common trait among fungi. Research on arbuscular mycorrhiza has dominated molecular-level studies, while other important associations—such as ectomycorrhiza, ericoid mycorrhiza, and endophytic fungi—remain comparatively understudied, despite the potential for multi-niche interactions. With the growing availability of genomic, evolutionary, and molecular tools, our understanding of fungal ecological niches can now be revisited. These approaches make it possible to unravel the shared and distinct molecular language governing ericoid, ectomycorrhizal, and endophytic associations, particularly in non-model plant species, across various natural (e.g., phosphorus-poor alpine environments, forest soils, wetlands, arid lands) ecosystems

Mycorrhizal symbioses are not static: both plants and fungi respond to one another and their environment over time. While spatial variation in mycorrhizal symbioses is well documented, the role of temporal dynamics remains underexplored. We know that mycorrhizal relationships vary over environmental gradients of aridity, temperature, and nutrient availability. However, the influence of timing on root and hyphal contact, the mutual exchange of resources over a growing season, or succession of the ecosystem cannot be fully captured from static measurements. Identifying the timing of processes across temporal scales is critical to correctly infer cause and effect in mycorrhizas. Without temporal context, we risk missing key insights for how global change will impact the composition and function of mycorrhizas within ecosystems. By investigating mycorrhizal dynamics over time, we can use past patterns to identify scalable community processes and forecast future functions in ecosystems.

Cellular and molecular dynamics across mycorrhizal interactions. Through a complex exchange of signals and nutrients between fungi and plants, mycorrhizas shape ecosystems, drive nutrient cycling, and influence plant health and productivity. Yet, despite over 150 years of research, the cellular and molecular mechanisms underlying these interactions remain remarkably diverse and incompletely understood. This symposium will explore how recent advances in genomics, cell biology, and symbiotic signalling are reshaping our understanding of the convergent and divergent traits that underpin arbuscular, ectomycorrhizal, orchid and ericoid symbioses. By bridging perspectives from evolutionary biology, molecular genetics, and biotechnology, the session will discuss how comparative approaches can illuminate both the unity and diversity of mycorrhizal strategies, and how this knowledge can be mobilized for sustainable solutions in a changing world.

Mycorrhizal research has been expanding in many new directions in recent years. While significant advances in molecular and cellular understanding of mycorrhizal fungi have dominated the last decade of research, there are also exciting new advances in our understanding of mycorrhizal fungal function driven by the development of new technologies and approaches. Here we aim to highlight the new approaches that are providing insights into how mycorrhizal fungi grow, respond to stress, forage for nutrients and alter ecosystem services. The methods we highlight in this session will be key to extending previous molecular and cellular work by connecting them to mycorrhizal fungal traits and their linked functions in order to make predictions about the impact of mycorrhizal fungi at the population, community, and ecosystem scale. These predictions will help us understand how mycorrhizal fungi will mitigate ecosystem responses to global change and land use change.

Mycorrhizas are well-known for the role they play in plant nutrient uptake and ecosystem nutrient cycling. Water, or the lack thereof, is another key resource intersecting with mycorrhizal function. In this symposium, we will broadly explore the connections between mycorrhizas and soil water. Across arid and Mediterranean ecosystems to boreal and temperate forests, we will investigate the direct and indirect roles of mycorrhizas on responses to drought and the movement of water through soils. From long-term studies to the newest experiments that spark novel lines of inquiry, we will assess the intersection between mycorrhizal function, water flow and its availability across ecosystems.

This session will focus on new and emerging techniques for understanding mycorrhizal functioning in ecosystems, including meta-omics techniques, global trait databases, and ways to combine techniques and approaches to achieve a better holistic understanding of mycorrhizal communities and ecosystem function. The session also considers innovative analytical tools and collaborative frameworks that can drive the next generation of mycorrhizal ecology.

Talk to a plant biologist, and they will say that the plant controls what mycorrhizal fungi are in its roots. Conversely, come to ICOM and you will get the opposite story. But what is true? Is there any evidence that either of the two organisms holds an upper hand? Over a decade ago, the first papers showing mycorrhizal fungi used effector-like proteins to manipulate plant hosts came out. So, it was settled. Mycorrhizal fungi were like pathogens and ruled it all. But then evidence began to come out that plants also used small secreted proteins that could influence mycorrhizal fungal growth. This symposium will hear some of the latest work undertaken in functional genomics studying the tools (e.g. proteins, miRNA, metabolites) used by both the mycorrhizal fungi and their hosts in negotiating symbiosis.

Interactions between animals and mycorrhizal fungi are essential for fungal dispersal, animal persistence, and soil nutrient cycling, but are comparatively understudied within mycorrhizal research. Spanning molecular to landscape scales across diverse animal and fungal taxa and mycorrhizal guilds, this symposium highlights the ecological and evolutionary factors shaping interactions between animals and mycorrhizal fungi, and the roles that these interactions play in supporting nutrient cycling, biodiversity, and ecosystem functioning. Speakers will also discuss how these animal-fungal interactions can be leveraged for restoration and conservation, essential at a time when climate change and biodiversity loss threaten to reshape ecological networks. This symposium seeks to advance understanding of the diversity of animal-mycorrhizal fungal interactions and to emphasise their key role in mycorrhizal fungal ecology.

Dispersal is a critical determinant for mycorrhizal fungi and plants by shaping species distribution and their ability to colonize new areas. These processes can deeply impact the dynamics of populations, species and communities at small to large scales. This symposium will discuss a range of mechanisms and vectors enabling mycorrhizal plants, fungi, and rhizosphere microbes to disperse, using innovative methods such as eDNA detection, trait-based ecology and prediction modelling. Speakers will address recent developments on movement ecology and showcase the impact of interkingdom interactions for ecological processes, including the monitoring of threatened and invasive species. will be presented to showcase recent ecology, and address .

Mycorrhizal fungi, in partnership with plant roots, drive nutrient uptake, carbon allocation, soil structure formation, and regulate soil organic matter (SOM) turnover, nutrient cycling, and ecosystem stability. Root and mycorrhizal traits, together with root and fungal adaptation strategies in ecology and evolution, influence SOM decomposition, nutrient release, and carbon sequestration, shaping biodiversity and terrestrial feedbacks to climate in a changing world. This session explores integrating trait-based approaches into SOM models to capture root and mycorrhizal adaptation effects across scales—from rhizosphere to global biogeochemistry. Topics include functional trait quantification, predictive modeling, and implications for nutrient availability, carbon stability, and ecosystem resilience. We aim to unite ecologists, soil scientists, mycologists, and modelers to advance trait-informed understanding of plant–fungus–soil feedbacks under global change.

While it is broadly recognized that soil microbes, especially root symbiotic fungi like mycorrhizal fungi, play important roles in plant community composition and nutrient cycling, their roles in mediating ecosystem responses to global change are far less explored. With estimates that more than 1/3 of annual CO2 emissions from fossil fuels is allocated belowground to mycorrhizal fungal mycelium, soil C stocks and storage are likely tightly linked to these fungi and their traits. The talks in this symposium will feature cutting-edge research on the role of mycorrhizal fungi in C cycling and storage and response to global change, in a diversity of systems from forests to row crops.

Invasive plants are a leading threat to biodiversity. Plant invasions occur when species take root, spread, and become dominant in ecosystems where they do not naturally belong. These invasive plants can upset ecological stability by outcompeting native species, changing soil properties, and influencing water resources. Most plant invaders form belowground associations with mycorrhizal fungi that may influence their invasion success. For example, some species acquire new mycorrhizal partners that increase their performance in invaded locations, while others have reduced performance due to a lack of compatible mycorrhizal partners. Understanding the role of plant-mycorrhizal dynamics in invasions is crucial for developing informed strategies to appropriately manage invasive plants and conserve native ecosystems above- and belowground.

Mycorrhizal fungi influence plant growth, reproduction, and survival, ultimately shaping plant community composition. Emerging research has begun to highlight the important role of this mutualism in plant invasions. However, a clear predictive understanding of when and how mycorrhizal fungi influence the establishment and spread of non-native species, and the repercussions to native flora and ecosystems, remains elusive. This symposium aims to bring together experts studying mycorrhizal-mediated plant invasions and related consequences. Diverse perspectives will enable a discussion of the major observational and experimental work that must be carried out to advance the field and move us toward a predictive understanding of the role of mycorrhizal fungi in plant invasions.

Mycorrhizal fungi influence the impacts of global change on ecosystem functioning. They can attenuate or even exacerbate the effects of environmental stress on host plants, and they contribute to soil organic matter formation and loss, ultimately shaping ecosystem carbon storage, water retention, and overall soil health. In this symposium, we will focus on the functional implications of mycorrhizal fungi in a changing world. Themes of interest include how mycorrhizal physiology, biodiversity, and functional attributes are linked to plant growth, decomposition, and soil organic matter cycling under global change. Emphasis on feedback to biogeochemical cycles, both above and belowground, covering all types of mycorrhizal fungi as well as their interactions with other fungi, prokaryotes, and eukaryotic microbes, will reveal how mycorrhizal fungi shape the ecosystems they inhabit, both today and into the future.

In this symposium, we will explore how fire shapes mycorrhizal communities and, in turn, how these symbioses influence post-fire ecosystem recovery. Speakers highlight cutting-edge work on fungal survival strategies, shifts in community composition across fire gradients, and the role of mycorrhizae in seedling establishment and soil stabilization after burns. By integrating ecological, physiological, and molecular perspectives, the symposium offers a comprehensive look at how fire regimes—from low-intensity burns to extreme wildfires—reshape plant–fungal partnerships in a changing climate.

Research on plant stress resilience is shifting from isolated individuals to community-level frameworks that capture ecological complexity and interactions among plants, microbiota, pests, and pathogens under global change. This session explores common mycorrhizal networks (CMN) as mediators of belowground interplant signaling and modulators of root-associated microbiomes. We invite studies revealing how CMN facilitate signal exchange and transfer plant-associated microbes through the hyphosphere, shaping host physiology and stress responses. Contributions may span experimental, theoretical, and modeling approaches, including multi-omics and ecological network analyses. Emphasis will be placed on mechanistic insights linking molecular signals to ecological outcomes and the functioning of plant–microbe holobionts. Perspectives on harnessing these interactions for resilient agriculture and forestry under global change are especially welcome.

To care for fungi and mycorrhizal symbiosis, we must first cultivate curiosity and empathy toward them in every earthling. Mycorrhizal fungi are a complex interface that links plants, microorganisms, soils, and ecosystems in intricate networks of exchange. Although mycorrhizal symbiosis is a concept sometimes difficult and abstract to grasp, it can be showcased by mycorrhizal scientists through photographs, stories, art and other creative expressions. Our aim through this symposium is to encourage as many mycorrhizal fungi researchers as possible around the world to build, through science outreach, a bridge between their scientific work and public interest. We want to highlight the efforts of our fellow scientists who engage with the public and are committed to raising awareness about mycorrhizal symbiosis. We will share new ways to experience the soils and mycorrhizal symbiosis so as to expand our relationship with the earth that nurtures us.

AM fungi are a common constituent of agricultural soils worldwide, and they are particularly relevant to cropping in areas where soils are geologically old and nutrient-poor. More recently, interest in commercial AM fungal products has been rapidly growing, and investment and R&D in commercial AM fungal products is also accelerating. However, there is limited scientific demonstration that the inoculation of field soils with AM fungi leads to increased crop yield. Many inoculants fail to colonize crop roots or persist in the soil after inoculation, which may be due to the lack of quality control frameworks in place for AM fungal products. While the focus of AM fungal inoculants has typically been on crop yield, the potential benefits to crop quality (including nutrition) has been less explored. In this symposium, we will explore the potential applications for AM fungi in agriculture with a focus on grain cropping, with an eye to the future of AM fungi in agricultural systems.

Mycorrhizal fungi play central roles in shaping plant responses to climatic disturbances, mediating drought tolerance, nutrient acquisition, carbon cycling, and community dynamics across ecosystems. Yet, the mechanisms linking mycorrhizal diversity and plant resistance and resilience to climate change remain poorly understood. This symposium brings together researchers integrating plant ecophysiology and performance with mycorrhizal ecology to illuminate how mycorrhizal symbioses influence plant performance under warming, drought and disturbance, and how these fungal communities impact plant resilience as these communities recover from disturbance. Speakers will integrate insights across physiology, ecology, and evolution to build a more mechanistic and cross-scale understanding of how mycorrhizas mediate plant and ecosystem responses to climatic disturbance.

In this symposium, we will examine the role of mycorrhizal symbioses in restoration ecology, highlighting how these fungi can enhance plant establishment, soil health, and ecosystem resilience. Presenters will discuss the selection and application of appropriate mycorrhizal partners for degraded landscapes, from reforestation and mine-site rehabilitation to grassland and wetland recovery. The session will explore emerging techniques for inoculation, sourcing local fungal communities, and monitoring restoration outcomes, while addressing challenges such as context dependency, biosecurity concerns, and variable field performance. Together, contributors will consider how integrating mycorrhizal knowledge can lead to more effective and enduring restoration strategies.

This symposium highlights the ecology, cultivation, and cultural significance of edible mycorrhizal fungi, bringing together researchers working on species such as truffles, matsutake, and other prized ectomycorrhizal mushrooms. Talks will explore the environmental and biological factors that shape their distribution, productivity, and symbiotic relationships with host trees, as well as emerging methods in sustainable harvesting, domestication, and forest management. The session will also consider the economic and gastronomic importance of these fungi, alongside the challenges posed by climate change, habitat loss, and market pressures. Together, participants will discuss pathways toward conserving and responsibly utilizing these valuable forest resources.

Talks and posters in this symposium focus on the practical use of mycorrhizal fungi to strengthen plant performance in the challenging environments of cities and managed landscapes. Presenters explore how mycorrhizal partnerships enhance nutrient uptake, drought tolerance, and disease resistance in ornamental, landscape, and container-grown plants. The session highlights applications in green roofs, street tree plantings, and urban restoration projects, emphasizing both the ecological benefits and the logistical considerations of inoculation. Together, these talks offer a forward-looking view of how mycorrhizae can help create more sustainable and resilient urban green spaces.

We will explore the rapidly expanding field of mycorrhizal inoculant development. Speakers will discuss advances in culturing techniques, bioreactor design, quality-control standards, and formulation methods that improve shelf life and performance in the field. Case studies from agriculture, forestry, and ecological restoration highlight both the promise and the practical challenges of bringing mycorrhizal products to market. The session aims to connect researchers, industry partners, and regulators to chart a path toward reliable, science-based bioinoculants that can support sustainable plant production at scale.