Mycorrhizal fungi

Mycorrhizal fungi are a diverse group of fungi that form symbiotic associations with plant roots. These associations, known as mycorrhizae, are critical for the nutrient uptake in most plants, enhancing their growth and survival. Mycorrhizal fungi are found in various ecosystems across the globe and play a vital role in soil biology and ecosystem dynamics.

Types of Mycorrhizal Associations

Mycorrhizal associations are categorized into several types, primarily based on the morphology of the interaction between the fungi and the plant roots, as well as the specific fungi involved.

Arbuscular Mycorrhizal Fungi (AMF)

Arbuscular mycorrhizal fungi form associations with the roots of approximately 80% of terrestrial plant species, including many crops. These fungi penetrate the root cells and form structures known as arbuscules, which facilitate nutrient exchange between the fungus and the plant.

Ectomycorrhizal Fungi

Ectomycorrhizal fungi form a sheath around the roots of mostly woody plants, including many trees such as pines and oaks. They do not penetrate the root cells but form a network of hyphae that extends far into the soil, increasing the surface area for water and nutrient absorption.

Ericoid Mycorrhizal Fungi

Ericoid mycorrhizal fungi associate with plants in the Ericaceae family, such as heathers and blueberries. These fungi penetrate the root cells and help the plant to access nutrients in nutrient-poor soils, typical of acidic environments.

Orchid Mycorrhizal Fungi

Orchid mycorrhizal fungi are associated with the roots of orchids. Orchids rely on these fungi not only for nutrient uptake but also for seed germination and early development, as orchid seeds do not contain stored nutrients.

Functions and Benefits

Mycorrhizal fungi play several critical roles:

• **Nutrient Exchange**: They enhance plant access to nutrients, particularly phosphorus and nitrogen, from the soil.
• **Water Absorption**: By extending the root system, they improve plant water uptake.
• **Disease Resistance**: They can help protect plants from root pathogens.
• **Stress Tolerance**: Mycorrhizal plants often exhibit better tolerance to environmental stresses such as drought and heavy metals.

Ecological Importance

Mycorrhizal fungi contribute to the structure and fertility of the soil. They are involved in nutrient cycling and help stabilize the soil by binding soil particles together with their hyphal networks. Their role in supporting plant health also contributes to ecosystem productivity and diversity.

Research and Applications

Research on mycorrhizal fungi has significant implications for agriculture, forestry, and environmental conservation. In agriculture, the use of mycorrhizal fungi can reduce the need for chemical fertilizers, promoting more sustainable farming practices. In ecological restoration, these fungi are used to improve the success of plant reintroductions and habitat recovery efforts.

See Also

• Soil biology
• Symbiosis
• Plant nutrition
• Ecological restoration