ABSTRACT
Fungi represent one of the three major crown lineages of eukaryotes, besides plants and animals. For their nutrition, fungi either decompose organic material or form symbiotic associations with other organisms. These symbiotic relationships vary from parasitic lifestyle, such as the rice blight fungus (Partida-Martinez and Hertweck 2005), which causes damage to rice seedlings and uses endosymbiotic bacteria for toxin production, to mutualistic relationships, such as endomycorrhizal relationships, the origin of which coincides with the early evolution of land plants (Simon et al. 1993). There is a continuum among symbiotic associations, from mutualistic to parasitic lifestyles, and some fungal species are known to exhibit different kinds of relationships with different hosts, such as species in the genus Colletotrichum, which can form mutualistic relationships with some plants and have parasitic relationship with other hosts (Redman, Dunigan, and Rodriguez 2001). In addition, at an evolutionary scale, changes of nutritional modes (parasitism versus mutualism) and inter-kingdom host switches have been shown to be common in fungi (Spatafora et al. 2007; Arnold et al. 2009).
