Susan M. Chambers

Ectomycorrhizal fungi : key genera in profile

1 Pisolithus.- 2 Suillus.- 3 Laccaria.- 4 Hebeloma.- 5 Rhizopogon.- 6 Tuber.- 7 Scleroderma.- 8 Amanita.- 9 Paxillus.- 10 Cantharellus.- 11 Lactarius.- 12 Cenococcum.- 13 Hysterangium.- 14 Thelephora.- 15 Resupinate Ectomycorrhizal Fungal Genera.

Symbiotic solution to arsenic contamination

Higher plants that are adapted to living on polluted soils are generally symbiotic with mycorrhizal fungi growing on contaminated sites. It is not known whether these fungi benefit their host plants simply by fulfilling their normal ecological functions, or by enhancing the plants resistance to pollutants. Arsenate contamination poses a particular challenge, as this toxin can enter plants through their phosphate transporters, causing mycorrhizal fungi to enhance both phosphate and arsenate uptake in plants. We have found a plant host and its mycorrhizal symbiont that have evolved in parallel to obtain phosphate but exclude arsenate.

Use of molecular methods to estimate the size and distribution of mycelial individuals of the ectomycorrhizal basidiomycete Pisolithus tinctorius

A field study was conduced to determine the size and spatial distribution of mycelial individuals of Pisolithus tinctorius at a site in NSW, Australia. Following collection and mapping of carpophores and isolation of the fungi into axenic culture, genomic DNA was extracted and combined data from RAPD and microsatellite analyses used to identify and map mycelial individuals. Thirty-three genetically distinct individuals were recognized at the field site and, while one large individual (at least 30 m diam.) was identified, most individuals appeared relatively small ( P. tinctorius mycelia through soil.

Molecular identification of Hymenoscyphus sp. from rhizoids of the leafy liverwort Cephaloziella exiliflora in Australia and Antarctica

Fungi isolated from the leafy liverwort Cephaloziella exiliflora collected in Australia and continental Antarctica were compared with Hymenoscyphus ericae using internal transcribed spacer (ITS) region DNA sequences. The isolates displayed C. exiliflora are probably H. ericae. The data significantly extend the known host range and geographical distribution of H. ericae and indicate that the fungus has a global distribution.

Intra- and interspecific variation in patterns of organic and inorganic nitrogen utilization by three Australian Pisolithus species

The ability of three Australian Pisolithus species, discriminated on the basis of ITS sequence data, to utilize a range of inorganic and organic nitrogen sources was assessed in liquid axenic culture. Both intra-, and putative interspecific, variation in nitrogen source utilization was observed. Most isolates demonstrated a preference for NH 4 + over NO 3 − , although some showed no significant preference for either inorganic source. All isolates utilized a range of amino acids. Species I isolates demonstrated a preference for acidic and/or neutral amino acids over basic acids, while species II and III isolates generally utilized amino acids poorly relative to species I. Although most isolates utilized BSA poorly, two species I isolates that had been maintained in axenic culture for > 10 y grew well on this substrate, suggesting possible changes in nitrogen utilization with extended storage in axenic culture.

Ericoid mycorrhizal fungi are common root inhabitants of non-Ericaceae plants in a south-eastern Australian sclerophyll forest

Fungi were isolated from the roots of 17 plant species from the families Apiaceae, Cunoniaceae, Cyperaceae, Droseraceae, Fabaceae-Mimosoideae, Lomandraceae, Myrtaceae, Pittosporaceae, Proteaceae and Stylidiaceae at a sclerophyll forest site in New South Wales, Australia. Internal transcribed spacer (ITS) restriction fragment length polymorphism (RFLP) and sequence comparisons indicated that the isolated fungi had affinities to a range of ascomycetes, basidiomycetes and zygomycetes. Four RFLP types had closest affinities to previously identified Helotiales ericoid mycorrhizal (ERM) or Oidiodendron spp. Isolates representing six RFLP types, which were variously isolated from all 17 plant species, formed ERM coils in hair root epidermal cells of Woollsia pungens (Ericaceae) under gnotobiotic conditions. Three of these isolates formed intercellular hyphae, intracellular hyphae and/or microsclerotia, which are typical of dark septate endophyte infection, in roots of Stylidium productum (Stylidiaceae), indicating an ability to form different types of association with roots of different hosts. Overall the data indicate that a broad range of plant taxa may act as repositories for ERM fungi in sclerophyll forest soil.

ITS rDNA sequence comparison of ericoid mycorrhizal endophytes from Woollsia pungens.

The ITS regions of 14 isolates of endophytic fungi obtained from the root systems of four Woollsia pungens plants were sequenced and compared to sequences of Hymenoscyphus ericae, Oidiodendron maius and to sequences from other fungal taxa currently available in the GenBank and EMBL nucleotide databases. Sequence data suggested that six distinct taxa were present in the root systems of the four plants and that up to four of these were present in the root system of a single plant. One of the endophytes was identified as an Oidiodendron species, while most other isolates probably belong to the Leotiales.

Molecular and biochemical evidence for manganese-dependent peroxidase activity in Tylospora fibrillosa

Gel-based and spectrophotometric assays were used to demonstrate expression of a manganese-dependent peroxidase (MnP) activity in culture filtrates of the ectomycorrhizal basidiomycete Tylospora fibrillosa. PCR amplification using a primer pair specific for a 260 bp fragment from the 5′-end of a gene encoding an H3-like MnP isozyme in Phanerochaete chrysosporium, produced single amplification products of 260 bp from DNA extracted from two isolates of T. fibrillosa. The amplified fragment from T. fibrillosa had a 93.7% nucleotide overlap (over 201 bases) with a published sequence for a 260 base amplification product from the P. chrysosporium H3 MnP isozyme gene, strongly suggesting the presence of a homologous gene in the ectomycorrhizal fungus. The results are discussed in the context of lignin degradation by ectomycorrhizal fungi.

Distribution and persistence of Amanita muscaria genotypes in Australian Pinus radiata plantations

Basidiomes of Amanita muscaria were collected from sites in three 30-36-yr-old Pinus radiata plantations in New South Wales, Australia. Following DNA extraction from basidiome stipes, inter-simple sequence repeat PCR using the degenerate primers 5’DHB(CGA) 5 and 5’DDB(CCA) 5 , was used to identify the mycelial genotypes from which basidiomes arose. Each site was found to contain 8-10 A. muscaria genotypes, with six genotypes common to all three sites and one common to two sites. The presence of common genotypes at the three sites is taken to indicate that they were introduced as vegetative inocula when seedlings were planted and have persisted for

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

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.