Fungal impacts on Earth's ecosystems

Abstract

Over the past billion years, the fungal kingdom has diversified to more than two million species, with over 95% still undescribed. Beyond the well-known macroscopic mushrooms and microscopic yeast, fungi are heterotrophs that feed on almost any organic carbon, recycling nutrients through the decay of dead plants and animals and sequestering carbon into Earth's ecosystems. Human-directed applications of fungi extend from leavened bread, alcoholic beverages and biofuels to pharmaceuticals, including antibiotics and psychoactive compounds. Conversely, fungal infections pose risks to ecosystems ranging from crops to wildlife to humans; these risks are driven, in part, by human and animal movement, and might be accelerating with climate change. Genomic surveys are expanding our knowledge of the true biodiversity of the fungal kingdom, and genome-editing tools make it possible to imagine harnessing these organisms to fuel the bioeconomy. Here, we examine the fungal threats facing civilization and investigate opportunities to use fungi to combat these threats.

Figure 1.. Climate change will disrupt fungal interactions in Earth’s ecosystems and will likely increase fungal diseases in plants, wildlife, and humans.

Environmental fungi play critical roles as decomposers – restoring nutrients, as mycorrhizal root symbionts – supporting plant growth, and in insect-fungus mutualisms. Perturbing the balance of these interactions will impact on Earth’s ecosystems. Rising global temperatures and severe weather events (hurricanes, floods, wildfires, drought) will increase the dispersal of fungal spores in the air and alter crop and soil health. The recent increased geographic spread of fungal diseases in wildlife, notably amphibian and bat populations, is driving species loss. The spread to new environments and hosts alongside selection by broad-spectrum and environmentally durable fungicides imposes selection on fungi to adapt to survive and is likely fueling emergence of new human fungal diseases, some of which are resistant to antifungals.

Figure 2.. Control strategies to combat fungal infections.

The circular format highlights the interconnectedness of humans, plants, and wildlife, illustrating how fungal pathogens impact all three domains of life and how control strategies often overlap across these systems. This interconnectedness is crucial, as advances in one domain, such as diagnostics or treatment methods in humans, can influence strategies in others, like agriculture or wildlife management. In healthy humans, colonization resistance keeps commensal fungi and invading pathogens from causing active infections. When fungi cause disease, rapid and specific diagnostics, and treatments (including immunotherapies and antifungal agents) represent a clinical priority. However, some classes of drugs used in clinical settings are also used in agriculture, increasing the risk for environmental fungi to become drug resistant. To mitigate fungal crop diseases, current efforts are focused on developing gene-edited crops, mycoviruses to target fungi, or dsRNAs to silence necessary pathogen genes on plant tissues. Fewer options exist for protecting wildlife and include developing vaccines for specific pathogens and mitigating disease drivers, such as curtailing environmental disturbance or providing artificial refuges to support wildlife population resilience, and limiting international trade of wildlife to prevent introduction of non-native pathogens into native host populations. The figure underscores that efforts to combat fungal pathogens must be viewed holistically, recognizing that shared environments and similar approaches contribute to both challenges and solutions across these domains.

Figure 3.. The fungal kingdom offers many known and emerging solutions to global challenges facing humanity, including those challenges that may be exacerbated due to climate change.

Mycorrhizal fungi associated with root structures store a substantial amount of global carbon underground, offering potential to harness fungi as a carbon sink. These fungi could also play an important role in supporting reforestation efforts and aiding in bioremediation. The rapid and low-cost growth of fungi make them ideal as protein substitutes for meat and dairy as we face agricultural losses and seek to reduce our dependence on food products with high carbon footprints. In addition to the possible use of fungi as myco-fuel, fungi are proving to be an incredible natural resource for sustainable fabrics, textiles, and building materials. Finally, although fungal diseases pose a threat to human health, fungi also have a tremendous capacity to be harvested for new antimicrobial medicines and therapeutics. Clearly, we are only beginning to capitalize on the myriad ways that fungi can be harnessed in technologies, medicines, food, and sustainable products.