micorizi

Micorizi are symbiotic associations between plant roots and fungi. In this mutualism, fungi colonize the root system and extend their hyphae into the surrounding soil, increasing the plant’s access to nutrients and water. The term is used in Romanian to describe mycorrhizal associations and is commonly referred to as mycorrhiza in English.

There are two major types: ectomycorrhiza and endomycorrhiza (the latter commonly called arbuscular mycorrhiza, AM). Ectomycorrhiza form a sheath around root tips and a network called the Hartig net between cortical cells, typical of many trees such as pines and oaks. Endomycorrhiza penetrate root cortical cells; arbuscules function as exchange sites. Arbuscular mycorrhizal fungi (AMF) belong mainly to the phylum Glomeromycota, with Rhizophagus irregularis among the best-studied species.

The mutualism is based on carbon exchange: plants supply sugars to the fungi, while fungi provide minerals (notably phosphorus) and water, in addition to improving soil structure through hyphal networks. Micorizi can also enhance plant resistance to certain pathogens and drought tolerance.

Ecologically, micorizi are ubiquitous in terrestrial ecosystems and influence plant community dynamics, productivity, and nutrient cycling. In agriculture and forestry, inoculation with beneficial fungi is used to promote crop establishment and reduce fertilizer needs, though effectiveness varies with soil and plant species.

History: The term mycorrhiza was coined by Albert Bernard Frank in 1885. Research continues to reveal the diversity of interactions, including common mycelial networks that connect multiple plants.