WAR of the MICROWORLDS
How do I kill Thee? Let me count the Ways! (# 37) click here for full list
Syncephalis nodosa: In forest and agricultural soils the biomass of fungi exceeds all other groups of micro- and meso-organisms combined (e.g. bacteria, copepods, nematodes, tardigardes, rotifers, ciliates, flagellates, amoebae and other protozoans, etc). Species in all of these groups attack fungi as a nutrient source. In turn, the fungi predate all other groups of microorganims. However, based on total biomass, the greatest potential nutrient source for parasitic fungi is OTHER fungi. It is not surprising then that many fungi attack their own kind as the 'raison d'etre' for life. Parasitism of one fungus my another is referred to as mycoparasitism and fungi following this strategy are called mycoparasites. One of the most interesting associations of mycoparasitism is in the division Zygomycota and there are a number of species of zygomycetes that parasitize other zygomycetes. In this example I show a species of Syncephalis (Family: Piptocephalidaceae) attacking a species of Rhizopus (Family: Mucoraceae). Both biotrophs and necrotrophs are found in this group (see note below paraphrased from Peter Jeffries stuff).
Left Micrograph: Image shows asexual reproduction in Syncephalis nodosa. Cylindrical merosporangia develop from the swollen vesicle. Spores are delimited in a linear series within each merosporangium. At maturity, individual sporangiospores disarticulate and are dispersed. In this micrograph premature disarticulation of the spores has been caused by physical stress during mounting. Right Micrograph: Young sporangiophore of a Syncephalis species showing early development of the merosporangia from the vesicle. The sporangiophore of the mycoparasite is anchored to the host fungus (Rhizopus) by a foot-like (hand-like?) appressorium. A very fine hypha of the mycoparasite can be seen tracing through the interior of the much broader hypha of the host.
Images from MycoAlbum CD by George Barron (contains these pictures and 1000 more)
Note: Mycoparasitism within the Zygomycetes. PETER JEFFRIES (Biological Laboratory, University of Kent) :- Peter Jeffries notes that the Zygomycetes include a number of mycoparasitic genera that differ in their strategies of parasitism. Some e.g. Piptocephalis are typical biotrophs, and display many features associated with this mode of infection, such as the formation of haustoria. Others, e.g. Spinellus, apparently form necrotrophic associations with moribund toadstools. There are also Zygomycetes, such Syncephalis that 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 (biotrophic), but it is followed by a rapid internal growth of parasitic hyphae and concomitant destruction of host cytoplasm (necrotrophic).
Merosporangia developing from the vesicle of Syncephalastrum (not a mycoparasite).
Sporangiole is the term used to describe a small sporangium. Merosporangium is just a specialized form of a sporangiole. In Syncephalastrum and Syncephalis the sporangioles grow finger-like and radiate from a swollen vesicle at the apex of the sporangiophore (stalk). The sporangiospores develop to form a linear seeries inside the sporangiole.