Population structure and mating system in Marasmius androsaceus Fr.



Isolates of the rhizomorph-forming fungus Marasmius androsaceus were obtained from four different sites in stands of either Norway spruce or Scots pine of different age. The mating system and the mycelial interactions within each site were studied. The fungus had a bifactorial mating system and genetically different dikaryons were strongly mutually antagonistic in culture. On the basis of such antagonism, up to 18 different individual genets could be found within an area of 2.8 m2. No differences between the four sites could be detected with respect to the size of the genets. Isolates belonging to the same genet were frequently found in close proximity in areas from which other types were excluded. However, the older plots contained genets with a discontinuous distribution in the plots. The likely origin of this distribution is discussed in relation to the pattern of dispersal, establishment and spread of this saprophytic fungus in different woodland habitats.