Common Types of Fungi Found in Soil: From Mycorrhizae to Saprotrophs‍

Image by Nghia Nguyen from Pixabay 

Soil fungi are among the most diverse and numerous microorganisms and impact biogeochemical cycles, soil structure, and plants. This blog will discuss the most common soil fungi, such as mycorrhizae, saprotrophs, decomposers, endophytes, plant diseases, predators, lichen- and mutualist-forming fungi, and truffle-forming fungi. These fungi have unique characteristics, and roles, and interact with the environment and other soil creatures.

We can better manage and appreciate soil ecosystems if we understand the diversity and roles of soil fungi.

Mycorrhizal Fungi

Mycorrhizal fungi are among the most well-known and studied soil fungi due to their symbiotic relationship with plants. Mycorrhizae are specialized fungal structures that form on the roots of most plants, providing them with increased access to water, nutrients, and protection from pathogens. Mycorrhizal fungi associate with over 90% of plant species, and they are essential for plant growth and survival in most terrestrial ecosystems.

There are two main types of mycorrhizal fungi: ectomycorrhizae and endo-mycorrhizae. Ectomycorrhizae form a sheath around the root tips, while endo-mycorrhizae penetrate the root cells.

Examples: Boletus, Amanita, and Rhizopogon.

Decomposer Fungi

Saprotrophs, or decomposer fungi, play a vital role in the breakdown and recycling of organic compounds in the soil. These fungi produce enzymes that break down complex organic chemicals into simpler molecules that can be absorbed by plants and other microbes. Decomposer fungi are critical for nitrogen cycling and soil organic matter formation. White rot fungi and brown rot fungi are the two forms of decomposer fungi. White-rot fungi are capable of degrading lignin, a complex polymer found in woody plants, whereas brown-rot fungi are capable of degrading cellulose and hemicellulose, both of which are key components of plant cell walls.

Examples: Agaricus, Pleurotus, and Trametes.

Endophytic Fungi

Endophytic fungi are fungi that live inside plant tissues without causing any apparent harm or disease. Endophytic fungi are widespread in most plant species, and they can affect plant-fungal interactions and ecosystem processes.

These fungi can provide plants with many benefits, such as increased resistance to stress, growth promotion, and nutrient uptake.

There are two main types of endophytic fungi: asymptomatic and symptomatic fungi. Asymptomatic fungi do not cause any visible symptoms in the host plant, while symptomatic fungi can cause mild to severe symptoms, including leaf spots, wilting, and stunting.

Examples: Colletotrichum, Fusarium, and Epichloë.

Plant Pathogenic Fungi

Plant pathogenic fungi are fungi that cause diseases in plants, ranging from mild leaf spots to severe wilting and death. These fungi can affect plant growth, productivity, and ecosystem services, and they can be challenging to control. Plant pathogenic fungi can infect various plant parts, including roots, stems, leaves, and fruits, and they can be transmitted by soil, water, air, and vectors.

There are many types of plant pathogenic fungi, including rusts, smuts, powdery mildews, and downy mildews.

Examples: Alternaria, Botrytis, and Phytophthora.

Predatory Fungi

Predatory fungi are fungi that feed on other fungi or bacteria, using various mechanisms, such as trapping, engulfing, or parasitizing. These fungi can affect soil fungal communities and nutrient cycling, and they can provide ecosystem services, such as disease suppression and pest control. Predatory fungi can be found in various soil habitats, including forests, grasslands, and wetlands.

There are many types of predatory fungi, including nematode-trapping fungi, amoeba-infecting fungi, and insect-pathogenic fungi.

Examples: Arthrobotrys, Dactylella, and Cordyceps.

Lichen-forming Fungi

Lichen-forming fungi are fungi that form mutualistic associations with photosynthetic partners, e.g. algae or cyanobacteria. These associations result in the formation of lichens, which are unique and diverse organisms with various ecological functions. Lichens can be found in various soil habitats, including rocks, trees, and soils, and they can affect soil organic matter, nutrient cycling, and carbon sequestration.

Lichens can also be indicators of air pollution and climate change.

There are many types of lichen-forming fungi, including crustose, foliose, and fruticose lichens.

Examples: Cladonia, Parmelia, and Usnea.

Mutualistic Fungi

Mutualistic fungi form beneficial associations with other organisms, such as plants, animals, or other fungi. These associations can result in increased nutrient uptake, protection from pathogens, and growth promotion. Mutualistic fungi can be found in various soil habitats, including rhizospheres, roots, and insect guts.

There are many types of mutualistic fungi, including mycorrhizae, endophytes, and symbiotic fungi.

Examples: Glomus, Piriformospora, and Aspergillus.

Truffle-forming Fungi

Truffle-forming fungi produce edible or valuable fruiting bodies, known as truffles. These fungi are mycorrhizal and have a specialized relationship with their host plants, often trees or shrubs. Truffles are highly prized for their unique aroma and flavor and have been used in culinary and medicinal applications for centuries.

Truffle-forming fungi can be found in various soil habitats, including forests, grasslands, and orchards.

There are many types of truffle-forming fungi, including Tuber, Terfezia, and Morchella.

Conclusion

Soil fungi have a variety of roles in soil ecosystems and are crucial to nutrient cycling, ecosystem services, and soil health. We can better appreciate and manage soil biodiversity and ecosystem functioning by being aware of the typical forms of fungus present in the soil. The production of soil aggregates, carbon sequestration, and plant productivity are all influenced by the interactions between soil fungi and other soil organisms including bacteria, protozoa, and nematodes. Mycology and taxonomy of fungi are constantly developing, and new understandings of the roles and purposes of soil fungi are emerging. We can improve soil quality and ecological sustainability by encouraging helpful fungi and controlling destructive fungi.