Mykorhizza

Mykorhizza, or mycorrhiza, is a symbiotic association between a fungus and the roots of a vascular plant. In this mutualistic relationship, the fungal partner colonizes the plant’s root system, extending its hyphae into the soil to increase the effective surface area for water and nutrient absorption. In return, the plant provides the fungus with carbohydrates produced by photosynthesis.

There are several major types. Ectomycorrhiza (ECM) form a sheath around roots and extend hyphae into the surrounding soil; they are common in many trees, including pines and oaks. Arbuscular mycorrhiza (AM), formerly vesicular-arbuscular mycorrhizae, colonize root cortical cells and form arbuscules that mediate nutrient exchange; AM is widespread among herbaceous plants and many crops. Other forms include ericoid mycorrhiza associated with ericaceous plants, and orchid mycorrhiza, which is essential for orchid seed germination and early growth.

Functions and benefits include enhanced uptake of phosphorus, nitrogen, and micronutrients, improved water absorption, and better soil aggregation through fungal networks. The association often increases plant drought resistance and can influence plant community dynamics via common mycorrhizal networks that connect multiple plants. In return for nutrients, fungi receive carbon compounds produced by the plant.

Ecology and history: mycorrhizal associations are ancient and widespread, present in the majority of land plant species. The term and concept were formalized in the late 19th century by Albert Bernhard Frank.

Applications include the use of mycorrhizal inoculants in agriculture and forestry to improve crop performance, soil health, and resilience, though effectiveness depends on host compatibility and environmental conditions.