XVI International Botanical Congess

Monotropa uniflora is a myco-heterotrophic plant. To further investigate its fungal symbionts, plants were sampled at 3 sites in BC (1 Betula papyrifera and 2 mixed wood sites). Root clusters (5) were harvested from each site and mycorrhizae were assessed by morphological and molecular (PCR-RFLP and DNA sequencing) methods. Analyses showed that each cluster (often several hundred tips) is possibly a fungal monoculture and that all ectomycorrhizae belonged to the genus Russula. Morphologically, mycorrhizae from 2 clusters lacked 1 of 2 characteristic cystidia exhibited by all other clusters. One RFLP variant included these 2 clusters displaying the single cystidial type, plus a cluster with both cystidial types. Molecular analysis resulted in 3 RFLP variants for all 15 clusters. Sequencing part of the ITS2 region of the rDNA suggests the 3 variants represent different Russula species. Both morphological and molecular assessments suggest low diversity and a high level of specificity in the Monotropa-fungal relationship.