Genotypic diversity in populations of a fungal endophyte from Douglas-fir

Rhabdocline parkeri, an endophyte of Douglas fir, forms symptomless infections within single epi-dermal cells of healthy needles. Rhabdocline parkeri strains were isolated from trees growing in varioushabitats ranging from virgin old growth forests to a single young tree growing isolated in a meadow.Different genotypes of R. parkeri were distinguished by using the Random Amplified PolymorphicDNA (RAPD) technique. A significantly lower number of R. parkeri genotypes per unit foliage wereisolated from trees within a 20-year-old managed stand and from an isolated tree than from old growthtrees. Foliage from young trees (20 years old) in a stand directly adjacent to the sampled old growthtrees showed levels of genotypic endophyte diversity comparable to that in the old growth trees.Genotypic diversity is estimated to be at least three orders of magnitude greater in foliage of the oldgrowth trees and adjacent young trees than in foliage from the managed stand and from an isolatedtree. This difference is ascribed to differences in tree age and access to inoculum.
Key Words: Douglas fir, fungal endophyte, genotypic diversity, population biology, RAPD