Mycoparasitism in the Zygomycetes

The Zygomycetes includes a number of mycoparasitic genera, which differ in their strategies of parasitism. Piptocephalis, Dispira, Dimargaris and Tieghemiomyces are typical biotrophs, and display many features associated with this mode of infection, such as the formation of haustoria. Dicranophora, Spinellus and Sylgiles, on the other hand, apparently form necrotrophic associations with moribund toadstools, although it is difficult to define the boundary between mycoparasitism and competitive saprophytism. There are also zygomycetes, such as Chaetocladium and Syncephalis, which have modes of infection which do not fit neatly into either category above, but apparently share necrotrophic and biotrophic characteristics. Initially the infection process of Syncephalis resembles that of Piptocephalis, but it is followed by a rapid internal growth of parasitic hyphae and concomitant destruction of host cytoplasm. Chaetocladium forms gall-like structures on suitable host fungi and its growth is enhanced by this association. Circumstantial evidence suggests that these galls are functionally different from those formed by Parasitella during a pseudo-sexual response to the presence of another fungus. Zygomycetes also act as hosts for several other mycoparasitic fungi.