Mycorrhizas are associations among Zigomicetes fungi and vascular plants roots. They are widespread throughout the plant kingdom over a broad ecological range. Two main groups are involved: ecto and endomycorrhizas, and a thirth type ectoendomycorrhizas because of morfoanatomical features. Vesicular-arbuscular mycorrhizas (VAM), Glomales order, produces fungal structures (vesicles and arbuscules) inter and intracelular in the córtex region of the roots. This fungi are obligate symbionts. VAM fungi could increase plants growth with improving phosphorus, zinc and copper uptake. As a rule, the VAM fungi are strongly or wholly dependent on the higher plants, whereas the plants may or may not benefit from this association. In some instances mycorrhizas are essencial, rarely parasitic. The edaphic conditions, specially phosphorus availlability, controls the association efficiency. Non-nutritional stimulus are expected to benefit plant growth when innoculated with VAM fungi.
mycorrhizas; vesicular-arbuscular mycorrhizas; VAM; mycorrhizas taxonomy
