ABSTRACT
Mycorrhizal fungi establish symbiotic, mutualistic relationships with the root systems of up to 90 percent plant species in natural conditions (see also Chapter 15 in this volume). Ectomycorrhizal fungi are especially important for most plants used in forestry, exchanging sugar, water or mineral metabolites with their hosts, and also making them more resistant to different types of biotic and abiotic stress, such as biological diseases, drought or mineral toxicity.
