Histological Studies of Mycorrhized Roots and Mycorrhizal-Like-Structures in Pine Roots

Several studies have shown the potential of using Ectomycorrhizal (ECM) fungi in conifer micropropagation to overcome the cessation of adventitious root development. In vitro inoculation promotes the re-growth of the root system induced previously by auxin treatments, facilitating acclimation and diminishing the losses of plants because of a weak root system that is incapable of water and nutrient absorption. During a series of mycorrhization experiments, cryostat and ultrafine cuts were used to study the morpho-histological transformation of the symbiotic roots. To obtain cryostat cuts from pine roots a method frequently used for animal tissue was adopted. Molecular methods allowed fungi identification in all the mycorrhization phases and in the acclimation of derived plants. Mycorrhizal-like-structures derived from in vitro culture and axenic liquid cultures of roots were microscopically analyzed and compare with mycorrhizal roots.