Should we breed for effective mycorrhiza symbioses?

Most species of useful plants are able to develop symbioses with arbuscular mycorrhizal fungi (AMF). The partnership between these fungi and host roots can lead to an enhanced tolerance of plants to abiotic and biotic stresses. The mycorrhizal technology developed in the last few years provides agricultural and horticultural practice with suitable commercial mycorrhizal inoculum for the inoculation of annual vegetables, ornamentals, perennial herbs, shrubs or trees. New inoculation methods for already established plants and the flexibility of modern inoculum products allow the inclusion of mycorrhizal technology within integrated plant production systems as important biological phytosanitary factors. Unfortunately the variability of host dependency on mycorrhizal fungi varies between cultivars. Because of a lack of suitable breeding markers it is discussed whether the degree of mycorrhizal root colonization and the character “mycorrhizal dependency” should be used as breeding markers. It is recommended to collect data about mycorrhiza formation of new cultivars during breeding processes.