Mycoparasitism

Abstract

Two biotrophic parasites (Calcarisporium parasiticum and Gonato-botrys simplex) are deficient for a growth factor, which they must absorb from living host cells or from the substrate to which this nutrient has been added. While the absence of the growth factor from a given fungus would result in immunity, its presence in a fungus does not necessarily result in susceptibility. The ability of these two mycoparasites to absorb the required nutrient from living host cells, probably by altering the permeability of the cell membrane, appears to be the basic factor underlying their successful parasitism. This theory would help to explain only one mode of parasitism and is not applicable to all parasites of this type. It is expected that other mycoparasites, possibly the haustorium-producing phycomycetes, will be found to be deficient for one or more nutrients, which they normally absorb from the living host cells. For the vast number of facts needed to answer these many questions we must turn to the biochemist or the fungus physiologist well founded in biochemistry and encourage them to investigate these basic problems. These are among the most challenging and most fascinating problems in biology. Progress will be slow and, with the almost unlimited supply of test fungi, it will be many years before our information will permit us to establish clearly the basic principles of mycoparasitism.