Long-lived individuals of the opportunistic fungal pathogen Armillaria gallica arise in
single mating events, and then grow vegetatively to occupy large territories including multiple
woody substrates. In effect, this leaves a spatial record of mutation, the detection of which
would allow new inferences about how fungal individuals grow and infect their hosts. In this
thesis, I first identified a large individual of A. gallica in eastern Ontario. I then searched for
genetic variation within this individual by focusing on the tandemly repeated rRNA gene cluster
and four microsatellite markers that are variable in the A. gallica population. I discovered a loss
of heterozygosity (LOH) in the rRNA gene-cluster region, forming two genotypes that show
significant spatial clustering in a Mantel test. My M.Sc. thesis research serves as a baseline for a
genome-wide study of the mutational dynamic within the vegetative growth phase of this large
and old Armillaria individual.MAS
