ERICOID MYCORRHIZAL FUNGI - CELLULAR AND MOLECULAR-BASES OF THEIR INTERACTIONS WITH THE HOST-PLANT

A number of soil-borne fungi are able to form typical ericoid mycorrhi zae with plants belonging to Ericales. Together with Hymenoscyphus eri cae, the first isolate from roots of ericaceous plants, other fungal s pecies belonging to the genus Oidiodendron and many sterile mycelia ha ve been recognized as mycorrhizal by several authors. A high genetic d iversity was even found when a population of ericoid mycorrhizal fungi isolated from a single plant of Calluna vulgaris was analysed with mo rphological and molecular techniques. Ericoid fungi have a relevant sa protrophic potential, as they can degrade several organic polymers pre sent in the soil matrices. Different cell wall degrading enzymes, whic h are part of this arsenal and are produced in vitro by several ericoi d fungi, have been investigated biochemically. Immunocytochemical stud ies on the production of pectin degrading enzymes during the infection process of host and non-host plants suggest that regulation mechanism s for the production of cell wall degrading enzymes in vivo may be a c rucial step for the establishment of successful mycorrhiza with host p lants.