mykorrhizalassociationer

Mycorrhizal associations are symbiotic relationships between plant roots and soil fungi that enhance nutrient and water uptake for the plant in exchange for carbon from photosynthesis. They are widespread in terrestrial ecosystems and influence plant growth, health, and soil properties.

There are several main types. Arbuscular mycorrhizae (AM) are the most common, with fungal hyphae penetrating root cortical cells to form arbuscules that facilitate nutrient exchange. Ectomycorrhizae (ECM) form a sheath around roots and a network called the Hartig net between root outer cells, extending the root surface without penetrating cell walls. Ericoid mycorrhizae associate with ericaceous plants in acidic soils, while orchid mycorrhizae are specialized associations essential for many orchid seeds to germinate and grow. AM fungi belong to Glomeromycota, whereas ECM fungi include various Basidiomycota and Ascomycota species.

Functionally, the fungal hyphae explore the soil far beyond the root zone, increasing acquisition of phosphorus, nitrogen, and micronutrients and improving water uptake. In return, plants supply sugars and other organic compounds to the fungi. The relationship can enhance plant growth, drought tolerance, and disease resistance, and it influences soil structure through fungal networks and compounds such as glomalin.

Understanding mycorrhizal associations has implications for agriculture, forestry, and ecosystem management, including the use of inoculants to improve establishment and resilience in unstable or nutrient-poor soils. Benefits are species- and context-dependent, reflecting a balance of costs and ecological conditions.