Relatively little research has been conducted on the historical and reproductive factors that affect genetic characteristics of fungi that form mutualistic associations with host trees. In an effort to elucidate the genetic structuring of the mutualistic ectomycorrhizal fungus, Russula brevipes, studies utilizing various molecular markers were designed to determine how historical and geographical barriers (e.g., ice ages and the formation of mountains) affect dispersal, genetic makeup and population differentiation. Collections of R. brevipes from many locations in the Pacific Northwest and Rocky Mountain region will be made to assess genetic differentiation.
Ectomycorrhizal fungi (EMF) form indispensable symbiotic relationships with tree roots by providing water and nutrients, increasing seedling survivability, and protecting against root pathogenic organisms. R. brevipes forms mutualistic associations with valuable timber and recreation trees in the western U.S. including lodgepole pine (Pinus contorta), Douglas fir (Pseudotsuga menziesii) and Sitka spruce (Picea sitchensis). In the Rocky Mountains, lodgepole pine is never replanted into massive clearcuts and regeneration is dependent on processes of natural seedling establishment and survival mediated by EMF. It is important to understand the population biology and genetic structure of EMF, particularly since these fungi may affect survivability of their hosts by mediating competition between species through interconnected networks below-ground.
