Systematics and taxonomy of Australian Cortinarius
Cortinarius is one of the largest and most complex fungal genera known today, with around 3000 described species. Cortinarius are agarics (gilled fungi) that develop ectomycorrhizal associations with many forest trees around the world, including Eucalyptus and Nothofagus. Cortinarius has numerous species in Australia that remain poorly documented, despite having important ecological roles and interesting chemical and antibiotic features. The identification of individual species can be extremely difficult when relying only on morphological and/or chemical characters. Our long-term goal is to provide rigorous species delimitation and phylogeny for Australian Cortinarius, integrating morphological, chemical and molecular data.
Our research currently focusses on the subgenus Dermocybe of Cortinarius. This subgenus contains brightly coloured species that produce anthraquinone pigments, which can also be found in some species of other subgenera. The National Herbarium of Victoria (MEL) at Royal Botanic Gardens Victoria houses more than 300 collections of subgenus Dermocybe, currently filed under 16 species names, with one third of the collections not identified to species. We are investigating species richness in the Australian members of subgenus Dermocybe and also phylogenetic relationships with northern hemisphere counterparts.
Using molecular data, a so-called 'barcode' region is of great use in delimiting species in the first place, and also as a diagnostic tool for identification of unknown material. A barcode region is a short sequence of DNA that is the same or very similar within a species, and unique for each different species. A workable barcode region will have a 'barcode gap', where the distance (dissimilarity) in a comparison between sequences of members of the same species will always be less than the distance between sequences from members of different species.
We are developing molecular barcodes using a set of 80 Victorian Dermocybe collections held in the National Herbarium of Victoria. These collections have been assigned to well-characterised groups based on our phenetic analysis of morphology and pigment composition (from thin layer chromatography). The suitability of different DNA regions to act as barcodes for species of subgenus Dermocybe is being investigated. We are examining the internal transcribed spacers (ITS) flanking the 5.8S ribosomal gene; the nuclear large-subunit ribosomal RNA gene; as well as the protein-coding genes gpd, mcm7, rpb1, rpb2, and tef1. Primer sets targetting different nuclear protein coding genes have been optimised or newly developed for specifically amplifying and sequencing members of subgenus Dermocybe. Inter- and intra-specific variations and relationships between closely related taxa are being investigated across data sets. The phylogenetic signal and the effectiveness in species delimitation of each potential barcode region are being analysed.
Results from this project show that:
- analysis of Cortinarius subgenus Dermocybe based on morphological and/or chemical data underestimates species richness, especially by missing cryptic species
- the ITS region is the easiest and most efficient marker to establish species boundaries within subgenus Dermocybe
- herbarium specimens are an important source for uncovering new species that have not yet been recognised and formally described.
Further studies will clarify the morphological and ecological characteristics of the cryptic species identified on molecular markers, and extend the species discovery to other groups within Cortinarius.
- Franck Stefani (Royal Botanic Gardens Victoria, 2010–2012)
- Kate Griffiths (Royal Botanic Gardens Victoria, Summer Student 2010/2011)
- Rodney H. Jones (Department of Primary Industries, Frankston)
- Tom May (Royal Botanic Gardens Victoria)
- Australian Biological Resources Study (ABRS) (Postgraduate scholarship for Rodney Jones)
- CYBEC Foundation (Jim Willis studentship for Kate Griffiths)
Stefani, F.O.P., Jones, R.H. and May, T.W. (28 November–3 December 2011). DNA barcode(s) for fungi: a case study in the subgenus Dermocybe ofCortinarius from southern Australia. Fourth International Barcode of Life Conference, Adelaide. (Conference paper).
Stefani, F.O.P., Jones, R.H. and May, T.W. (23–30 July 2011). Integrative taxonomy: a case study in the subgenus Dermocybe of Cortinarius (Fungi: Agaricomycetidae). XVIII International Botanical Congress, Melbourne. (Poster).
Stefani, F.O.P., Jones, R.H. and May, T.W. (2014). Concordance of seven gene genealogies compared to phenotypic data reveals multiple cryptic species in Australian dermocyboid Cortinarius (Agaricales). Molecular Phylogenetics & Evolution 71, 249–260.
Schoch, C.L., Seifert, K.A., Huhndorf, S., Robert, V., Spouge, J.L., Levesque, C.A., Chen, W. and Fungal Barcoding Consortium [including Griffiths, K., May, T.W. and Stefani, F.O.P.] (2012). Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi. Proceedings of the National Academy of Sciences of the United States of America 109, 6241–6246.
Beattie, K.D., Thompson, D.R., Tiralongo, E., Ratkowsky, D., May, T.W. and Gill, M. (2011). Austrocolorone B and austrocolorin B1, cytotoxic anthracenone dimers from the Tasmanian mushroom Cortinarius vinosipes Gasparini. Tetrahedron Letters 52, 5448–5451.
Beattie, K.D., Raouf, R., Gander, L., May, T.W., Ratkowsky, D., Donner, C.D., Gill, M., Grice, I.D. and Tiralongo, E. (2010). Antibacterial metabolites from Australian macrofungi from the genus Cortinarius. Phytochemistry 71, 948–955.
Jones, R.H. and May, T.W. (2008). Pigment chemistry and morphology support recognition of Cortinarius austrocinnabarinus sp. nov. (Fungi: Cortinariaceae) from Australia. Muelleria 26, 77–87.
Watling, R., Gill, M., Giménez, A. and May, T.W. (1992). A new styrylpyrone-containing Cortinarius from Australia. Mycological Research 96, 743–748.