This third updated and revised edition strongly emphasises on genetics and molecular biology. It falls into a time period with an exceptionally rapid growth in mycorrhizal research. A vast expansion of interest in mycorrhiza is manifest worldwide, resulting in public awareness that the productivity of plants and the quality of leaves, flowers, fruits and seeds are determined by the activities of root systems and their associated physical, chemical and biological environment. Symbiotic fungi have become an important object of tests to evaluate some of the new opportunities being developed in biotechnology. While these fungi have been used to stabilize eroded soils and the forests since the turn of century, the novelty in recent years has increased recognition that biological processes can be manipulated genetically, opening numerous unexplored opportunities for the optimization of plant productivity in both managed and natural ecosystems, while minimizing the risks of environmental damage. The book contains the state of knowledge and theories on the structure, function, molecular biology and biotechnological applications of mycorrhizas and is thus of interest to a diverse audience of researchers and instructors.