The oldest fungi found in the fossil record is thought to be approximately 900 million years old and fungi may possibly be among the oldest eukaryotic organisms (basically everything that is not a bacteria or cyanobacteria), on the planet!
Fungi are popular to society because of their use as medicines (Penicillium), as a bioremediation tool and due to their inclusion in the human diet through a variety of foods including truffles, cheeses (moulds), breads (leavening), soy sauce, alcohol and as yeasts used in beer and wine making. Most beer and wine making yeasts are actually made of strains from a single species of yeast called Saccharomyces cerevisiae (latin for sugar fungi), that ferments carbohydrates (glucose into ethyl alcohol + CO2). Saccharomyces pastorianus of the same genus, is primarily used to make lager beers. S. cerevisiae was the first eukaryotic genome that had its DNA completely sequenced (Wikipedia 2010).
Approximately 80% of the commercial production of edible mushrooms for the worldwide human market consists of the Field Mushroom (Agaricus bisporus) and the Shiitake Mushroom (Lentinus edodes).
Fungi not only serve as an important resource for human society, but fungi also form an important part of non-human ecosystems as a food source for at least 30 species of Australian mammals (ANBG 2010), as well as insects and plants. The interaction between fungi and plants is explained in more detail below under Mycorrhizal Symbiosis.
Generally, fungi are rapidly growing organisms found in a variety of substrates and consist of branching, thread-like (filamentous) hyphae that mass together to form a mycelium. The fungi feeds via the mycelium either on dead or decaying matter (saprotrophic), or as a parasite on living organisms. It feeds by secreting enzymes in order to break substances down into a suitable food source - usually simple sugars.
When two compatible mycelia meet to form a dikaryotic mycelium (mycelium with two nuclei in each of its cells), it may form a fruiting body - more commonly known as a 'mushroom'.
The cell walls of fungi are made of a non-photosynthetic substance called chitin which is also the same substance that forms a variety of insect and crustacean (eg: crabs), body parts.
Around four-fifths of all vascular plants form symbiotic associations called mycorrhizae, with fungi. Symbiotic relationships are a way for organisms to survive by being mutally beneficial to each other. Mycorrhizal symbiosis is featured on this site because much of the Australian flora including Eucalypts, Acacias, Casuarina, Nothofagus and Leptospermum form such relationships.
In the mycorrhizal symbiotic relationship, plants provide food to fungi which then store it as glycogen (sugar). The mycorrhizal fungi provide protection against pathogens, improve soil structure and help facilitate the uptake of nutrients available in the soils. By secreting enzymes and organic acids, the fungi breaks down material into forms that plants can utilize and can also help deter pathogens from infecting the plant.
Mycorrhizal fungi are a critical component in the soil - even seedlings grown in nturient rich soils don't do well without mycorrhizal fungi. Usually 0.1% by volume of mycorrhizal fungi is required to be present in soils in order for plants to flourish.
Endomycorrhizas have most of the fungus inside the root and are mainly made up of the fungus group Zygomycetes. Zygomycetes are very good at capturing phosphates from the soil and facilitating the uptake of this essential element to plants. This is particulary important in tropical areas where the soils are positively charged and tend to 'hold' the phosphates rather than make it easily available for plants.
Ectomycorrhizas have most of the fungus outside their roots and consist primarily of the fungus groups basidiomycetes and ascomycetes. These types of fungi groups include the macrofungi (with fruiting bodies visible to the unaided eye), including mushrooms, puffballs, coral fungi and shelf or bracket fungi. Ectomycorrhizas occur on Eucalyptus, Nothofagus (beech), Leptospermum, Casuarina and Acacia. Ectomycorrhizas are thought to protect the plants by making them more resistant to cold, dry and harsh conditions common in the temperate zones.
Identifications:
Attempts have been made to identify the fungi featured on this site using various publications on Australian fungi - please note however that they may not be accurate identifications and that further research may be required to confirm to species level. This is especially relevant when differences between species may require a microscope to determine rather than a comparison between easily visible features.
To view the fungi gallery click here
Sources:
Australian National Botanic Gardens (ANBG) 2010, Truffel-like fungi in Australia, viewed 13/2/2010, http://www.anbg.gov.au/fungi/truffle-like.html
Raven, P, Evert, R, Eichhorn, S, 1987 Biology of Plants, Worth Publishers, New York.
Warcup, J.H., 1980 Ectomycorrhizal Associations of Australian Indigenous Plants, New Phytologist, Vol. 85, Iss. 4, pp. 531-535.
