Identical genotypes of an ericoid mycorrhiza-forming fungus occur in roots of Epacris pulchella (Ericaceae) and Leptospermum polygalifolium (Myrtaceae) in an Australian sclerophyll forest

Abstract

Assemblages of fungi associated with roots of cooccurring Epacris pulchella (Ericaceae) and Leptospermum polygalifolium (Myrtaceae) seedlings at a sclerophyll forest site in New South Wales, Australia, were investigated by direct DNA extraction and analysis of rRNA gene internal transcribed spacer (ITS) products by denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) analyses. While ordination of the DGGE data suggested that the assemblages did not differ significantly between the two plant taxa, T-RFLP data provided marginal statistical support for the presence of different assemblages. Fungi isolated from roots of both plants were identified by ITS sequence comparisons largely as ascomycetes, several of which had close sequence identity to Helotiales ericoid mycorrhizal (ERM) fungi. One isolate morphotype from E. pulchella had close sequence similarity to ectomycorrhizal fungi in the Cenococcum geophilum complex, and neighbour-joining analysis grouped this strongly with other Australian C. geophilum-like sequences. Distribution of genotypes of an ERM Helotiales ascomycete in root systems of the two plant taxa was also investigated using inter-simple sequence repeat (ISSR)-PCR. Nineteen ISSR genotypes were identified, two of which were present in roots of both plant taxa. The results are discussed in the context of potential mycelial connections between Ericaceae and non-Ericaceae plants.