Ever wonder about the extraordinary cellular contents of arbuscular mycorrhizal fungi, and how the unique arrangement of these contents enables complex flows and nutrient exchange processes across open-pipe networks? This paper is a deep dive into cell wall composition, cytoplasmic contents, nuclear and lipid organisation and dynamics, network architecture, and connectivity.

New study finds that 83% of ectomycorrhizal fungi are known only by their DNA sequences that can’t be linked to named or described species, posing problems for conservation.

Published in Current Biology, the findings revealed that only 155,000 of the roughly 2-3 million fungal species on the planet have been formally described.

The team uncovered that dark taxa of ectomycorrhizal fungi are not spread evenly across the Earth, with significant concentrations of dark taxa in tropical regions like Southeast Asia and parts of South America and Africa, highlighting the need for more research and funding to explore these underground ecosystems.

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This study shows that wind patterns, more than geographic distance, shape the structure and diversity of North American soil fungal communities, particularly for wind-dispersed fungi, highlighting wind's critical role in fungal dispersal and its implications under climate change.

By tracking half a million fungal highways and the traffic flows within them, researchers describe how plants and symbiotic fungi build efficient supply chains

The team built an imaging robot that allowed them to gather 100 years’ worth of microscopy data in under 3 years

Work advances our understanding of how fungi move billions of tons of CO₂ into underground ecosystems each year

New research published in the science journal Nature used advanced robotics to track the hyper-efficient supply chains formed between plants and mycorrhizal fungi as they trade carbon and nutrients across the complex, living networks that help regulate the Earth’s atmosphere and ecosystems.

Understanding plant-fungal trade is urgent because these fungal networks draw down around 13 billion tons of CO2 per year into the soil - equivalent to ~1/3 of global energy-related emissions. More than 80% of plant species on Earth form partnerships with mycorrhizal fungi, in which phosphorus and nitrogen collected by fungi is exchanged for plant carbon. Despite their global importance, scientists did not understand how these brainless organisms construct expansive and efficient supply chains across their underground networks.  

Using a custom-built imaging robot, the international research team of 28 scientists discovered that the fungi construct a lace-like mycelial network that moves carbon outward from plant roots in a wave-like formation. To support this growth, fungi move resources to-and-from plant roots using a system of two-way traffic, controlling flow speed and width of these fungal highways as needed. To seek further resources, the fungi deployed special growing branches as microscopic ‘pathfinders’ to explore new territory, appearing to favor trade opportunities with future plant partners over short-term growth within immediate surroundings. The researchers describe how these behaviors appear to be coordinated by simple, local “rules” that prevent the fungus from “over-building” and define a unique ‘travelling wave strategy’ for growth, resource exploration, and trade.

Dr. Adriana Corrales, Director of SPUN's Underground Explorers program, is lead author of this research article, which looks at ectomycorrhizal (ECM) populations associated with trees in Bogotá, Colombia.

The study explores the community composition of root-associated fungi of Quercus humboldtii (Fagaceae), a tropical ectomycorrhizal tree species.

Urban landscapes are expanding worldwide, which means that the diversity and structure of ectomycorrhizal communities in urban settings could be affected.In this case, the Andean oak is planted as an urban tree in Bogotá. The authors explain that root-associated fungal communities of this tree differ between those growing in natural and urban settings.

This is important research because it provides insights as to how mycorrhizal fungi and host tree  relationships change  under urbanization pressures.

In this case, the authors found that:

1. Urban trees are important as reservoirs of underground fungal diversity.
2. Urban conditions favor fungal species adapted to more disturbed ecosystems.

Ectomycorrhizal fungi form trading relationships with trees. Trees in most boreal and temperate forests depend on these ectomycorrhizal [hyperlink definition] associations.The way the relationships change under different environmental conditions can tell us how both partners are adapting over time, in this case  largely due to threats such as human encroachment and urbanisation.

Few studies have focused on the structure of fungal communities in urban ecosystems, despite their importance to tree and ecosystem health. Specifically, Quercus forms associations with ECM fungi that contribute to the provide the trees with key nutrients and underpin soil biogeochemical processes. Additionally, urban landscapes are expanding, and increasingly provide habitat for wild species as  more encroachment takes place.

In conclusion, the authors report significant differences in the community composition of fungi present in the roots of rural and urban trees, with rural communities being dominated by Russula and Lactarius and urban communities by Scleroderma, Hydnangium, and Trechispora. These findings suggest a high impact of urban disturbances on ectomycorrhizal fungal communities.

How can we better understand, protect, and appreciate the role bacteria and fungi play in keeping urban plant communities healthy?

While cities are stressful environments for plants, symbiotic fungi and bacteria can provide nutrients, water, and help plants to cope with urban stress.

The authors aim to:

• Identify solutions to help plants grow in stressful environments
• Better incorporate plant–microbe symbiosis in green architecture

In natural ecosystems, plants live in symbiosis with fungi, bacteria, and other microbes which can help alleviate stress. Plant communities in cities help maintain the health and stability of urban ecosystems and their inhabitants. Specifically, plants in cities provide ecological benefits including  cooling urban “heat islands” and providing habitats for other plants, animals, and microorganisms.

Many key stressors  can be mitigated by symbiotic fungi and bacteria, including dependency on fertilizers, pathogens, drought, fewer pollinators, pollution, and reduced plant biodiversity.

The authors point out that, as is often the case, past research has focused on aboveground activity.  While the benefits of greenspace have been well-recognized, the soil life that lies beneath urban environments is rarely recognized for its important ecosystem functions. The authors stress that the microbial communities that support these spaces have been largely ignored.

Underground microbial communities of fungi and bacteria are also responsible for nutrient cycling, carbon storage, pathogen protection, and provide key functions leading to ecosystem stability.

Many excellent studies on carbon flows in mycorrhizal fungi had been done, but until this study nobody had harmonized the data.

We found that 13 billion tons of carbon are cycled through fungal networks annually.

Our goal was to synthesize all the data currently out there to try and better understand the carbon cycling.

Mycorrhizal mycelium act as a global carbon pool.

We've known for quite some time that carbon flows from plants into mycorrhizal fungi. It’s one of the central pieces to this type of plant-fungal symbiosis. But until now, we haven't had a good global estimate of how much that flow of carbon is. There have been some back-of-the-envelope calculations and small-scale studies, but the numbers varied a lot. With this review, our goal was to synthesize all the data currently out there to try and better understand this overlooked component of the carbon cycle.

We know that mycorrhizal fungi are holding carbon. Plants photosynthesize using sunlight and carbon dioxide from the atmosphere and convert them into energy. During that process, the plants fix carbon – turning it from its gaseous form into organic carbon compounds. The plants then use this carbon to build their structures. Flowers, leaves, stems – those are all made from organic carbon compounds.

We looked primarily at three different types of mycorrhizal fungi – arbuscular, ectomycorrhizal, and ericoid, and were able to find that collectively, these three groups of fungi have 13.12 billion tons of carbon dioxide allocated to them every year.

To put this number in perspective: 13.12 billion tons of CO2 is about 36% of global fossil fuel emissions last year. China is by far the biggest emitter of greenhouse gasses – its annual emissions in 2021 were 12.47 billion tons. The U.S. emitted 4.75 billion tons of carbon dioxide in 2021 – mycorrhizal fungi take up nearly three times that each year.

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Most plants need help to obtain and absorb nutrients and water. Many get this support via symbiotic relationships with underground fungi called arbuscular mycorrhizal (AM) fungi. While scientists know a lot about how these fungi benefit plants, they’re just beginning to understand the genes and DNA of AM fungi. In this study, researchers created a nearly complete genetic map (or genome) of a common AM fungus called Rhizophagus irregularis using advanced DNA sequencing techniques.

With this genetic map, the researchers  identified important genes and DNA patterns. They found that many genes related to moving nutrients in and out of cells were around before AM fungi even evolved, showing these genes have been present for an exceptionally long time. They also discovered new genes that only exist in this fungal group. Another key finding was that recently evolved areas in the DNA produce many small RNA molecules, which seem to help the fungus control its genetic information. This detailed map gives scientists new insights into how AM fungi have evolved to live and grow as obligate partners to plants.