Consideration of the taxonomy and biodiversity of Australian ectomycorrhizal fungi

Abstract

Mycorrhiza management in forestry must be predicated on an understanding of fungal biology and ecology. A fundamental building block of the biology and ecology of any organism is accurate identification and an understanding of its relationship to other organisms.

The taxonomy of the larger fungi has been largely based on morphological classification of sexual structures but now Taxonomy routinely incorporates mating studies, and biochemical and molecular data. Taxonomy may not revolutionize theories on mycorrhiza but can clarify some of the inconsistencies due to misrepresentation or over-generalizations and inappropriate conclusions drawn from studies with inaccurately identified fungi. To illustrate this, we discuss and example where incorrect fungal names were repeatedly erroneously applied in morphological and physiological research reports on this fungus, e.g. Laccaria laccata. In this case subsequent taxonomic study revealed the reason for the conflicting research results reported for this fungus.

We discuss the status of identifying the ectomycorrhizal fungi in various forest communities in Australia and the relationships of this process to assessing their use in forestry. Recent intensive efforts to collect, isolate and identify Australian ectomycorrhizal fungi have revealed an enormous and unique species diversity, e.g., for truffle-like fungi, over 2000 collections from the last five years alone have yielded 2 new families, 24 new genera, and about 184 new species. Nearly 95% of the described and undescribed fungi from Australia are novel, with some 22 genera and 3 families endemic. In most cases the current systematic knowledge of mycorrhizal fungi is inadequate to support clear framework for Australian taxa. This reflects the traditional Northern Hemisphere view of the world, the uniqueness of the Australian fungal flora, and how poorly it is known. For example, the genus Hymenogaster had been widely acknowledged as the most reduced member of the Cortinariaceae. However recent work on Hymenogaster species from the Southern Hemisphere has offered a number of alternative affinities to various species.

We also discuss the role proper identification of the organisms involved plays in understanding the ecosystem. Emphasis should be placed on how species diversity equates with physiological and genetic diversity and how a sound taxonomic understanding of species and their systematic position is essential to properly manage them. Accurate taxonomic information will continue to be required as the basis for assessing the role of ectomycorrhizal fungi in sustained ecological development. Of particular significance is the role of ectomycorrhizal fungi in maintenance of plant diversity in natural ecosystems and those disturbed by management. In conclusion, we present some key research areas involving the use of taxonomy that need priority attention.