Most mycorrhizal fungi live their entire lives underground – many of them don’t even make mushrooms, the fruiting bodies of fungi that pop up above the soil level. The hidden nature of these organisms can make studying them particularly challenging. For organisms like plants and animals, scientists can gather observational data, counting and recording or tagging study subjects. When it comes to belowground fungi and microbes, these surveys become more complicated.

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. 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.

Worldwide urban landscapes are expanding because of the growing human population. However, studies focusing on the diversity and structure of ectomycorrhizal communities in urban settings are uncommon. In Colombia, the Andean oak is an ectomycorrhizal tree thriving in tropical montane forests hosting a high diversity of ectomycorrhizal fungi. The Andean oak is planted as an urban tree in Bogotá, Colombia. The authors studied how root-associated fungal communities of this tree change between natural and urban areas. They found that urban Andean oaks can host a high number of ectomycorrhizal fungi in their roots, but that urban pollution could be favoring stress tolerant communities that are completely different from those at rural sites.

Cities are stressful environments for plants, plagued by heat, pollution, and biodiversity loss. As a result, plant communities tend to suffer in green roofs, parks, and living walls. Finding solutions to help plants grow in stressful environments is a goal of the sustainable city. One solution is to better incorporate plant–microbe symbiosis in green architecture. Symbiotic fungi and bacteria can provide nutrients, water, and help plants to cope with urban stress. The reconceptualization of green infrastructure from a microbial-focused perspective has the potential to improve plant health, growth, and diversity in cities.

Incorporating mutualistic symbioses into green infrastructure and landscape architecture is a sustainable way to enhance urban greenspace. In this paper, the authors discuss how symbiotic fungi and bacteria can help mitigate stressors for plants in cities.

The root systems of most plant species are aided by the soil-foraging capacities of symbiotic arbuscular mycorrhizal fungi from the Glomeromycotina subphylum. In this paper, the authors assemble the genome of Rhizophagus irregularis, the model species for studying arbuscular mycorrhizal fungi in the laboratory. Understanding the biology and genetics of any organism relies on the presence of a high-quality ‘reference genome’. Conducting this chromosome-scale view of the genome of an arbuscular mycorrhizal fungus genome, the authors reveal previously unexplored sources of genomic novelty in an organism evolving under an obligate symbiotic life cycle.