Category: Fungi & Lichens
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Fungi exist as single celled yeasts or multicellular structures made of filamentous tubes or 'hyphae', both with cell walls composed of glucose polymers (most commonly chitin). Although as a groupo fungi are distinct from plants and animals, molecular evidence strongly supports quite a close relatiopnsihp to the animals (planst are more distant). This divergence occured at least 900 Ma ago, while plant-associated forms (Glomales) have been found in the Ordovician (460 Ma). Fungi gain their nutrition from surrounding plant or animal tissue, principally through exporting hydrolytic enzymes and absorbing the resulting simple molecules. Fungal reproduction occurs by dispersal and germination of mitotic (clonal) or meiotic (sexual) spores, mating partners finding each other through oligopeptide or complex organic pheromones. Interestingly, several fungi have independently evolved explosive mechanisms for launching spores (at an acceleration that would flatten a human!), whereas others rely on wind or water for dispersal.
The classification of fungi has undergone some radical shifts as new molecular data have appeared in recent years. Four major divisions of fungi are now recognised, including ascomycetes, basidiomycetes, zygomycetes and the less diverse chytridomycetes. Within the basidiomycetes we find the largest living organism on Earth, namely Armillaria (honey-fungus), where a single clonal individual may occupy almost 1000 hectares and be over 8,500 years old. The chytrids are the most primitive fungi, retaining a flagellum and also possessing rhodopsin as a sensory molecule. An important subsidiary group is the 'Glomeromycota', which is very closely related to the zygomycetes and includes the mycorrhizal fungus Glomus and its allies. Of significance regarding convergence, certain very fungus-like groups apparently have protistan origins, including water moulds (e.g. late potato blight, Phytophthora infestans), cellular slime moulds (e.g. the intriguing 'social' microbe Dictyostelium), plasmodial slime moulds and parasitic Microsporidia.
Virtually all types of fungi form associations, both symbiotic and pathogenic with plants and animals, among which we find myriad examples of convergence. Mutualistic associations between fungi and plants have been important since plants moved to land, especially as arbuscular mycorrhizal (AM) fungi in plant roots or endophytes in the main plant body. Disastrous fungal plant pathogens are rife, and include the famous Dutch Elm disease, potato blight and wheat rust. Around 25% of fungal species form lichens, which are symbiotic associations with cyanobacteria or green algae, and here too convergences are frequent. An increasing number of animal-fungus associations are known, including fungi in the guts and ectodermal 'pockets' of various unrelated insects and crustacea, cultivation of fungi by ants, termites and ambrosia beetles for nourishment, and by scale bugs for protection. Humans suffer from numerous fungal pathogens, for example athlete's foot, ringworm, dandruff and in those with weakened immune systems, infections by Aspergillus fumigatus and Candida albicans can be very dangerous. Fungi are also of immense benefit to humans, as domesticated yeasts are used in making bread, beer and wine, Penicillium in certain cheeses and the life-saving antibiotic penicillin, and several fungi are genetic 'model' organisms (e.g. budding yeast Saccharomyces cerevisiae, fission yeast Shizosaccharomyces pombe, and filamentous Neurospora crassa).
| Topic title | Teaser text | Availability |
|---|---|---|
| Pheromone use in animals, fungi and plants | n/a | Unavailable |
| Endophytic fungi | n/a | Unavailable |
| Mycorrhizal fungus associations in plants | n/a | Unavailable |
| Agriculture in wood wasps | The most famous hymenopteran farmers are, without doubt, the attine ants. Rightly so, but they are not the only ones... | Available |
| Agriculture in gall midges (Diptera) | Flies, fungi, farming - sounds interesting? Read on if you want to learn about some rather different gall midges... | Available |
| Agriculture in beetles | Think of weevils and most likely you'll think of spoiled food. But some weevils have turned to farming... | Available |
| Hydrogenosomes and mitosomes | n/a | Unavailable |
| Lichens: fungal association with cyanobacteria and green algae | n/a | Unavailable |
| Mimicry in fungi | Insects pollinating flowers are a familiar sight. But what happens when the "flower" is actually a fungus? Still "pollination", but now it is fungal spores. Read on to learn more about the fungi that mimic flowers... | Available |
| Bioluminescence in fungi | n/a | Unavailable |
| Water-moulds (oomycetes) | n/a | Unavailable |
| Explosive discharge in fungi and plants | The very rapid release of reproductive bodies is perhaps most famous in the fungi, where several methods of flinging spores at high velocity have evolved independently. | Available |
| Mushrooms and their relatives (Basidiomycota) | Mushrooms are not only tasty, but also provide numerous examples of evolutionary convergence... | Available |
| Fungus-Insect associations | It is clear than an ascomycete yeast in a planthopper has been acquired quite independently of the beetles which employ a true yeast. | Unavailable |
| Carnivorous fungi: a diet of worms (and other animals) | Fungi have learnt how to trap living prey, notably nematodes but also a range of other animals include rotifers, tardigrades and even springtails. | Available |
| Ascomycete fungi: insights into convergence | Today ascomycetes are an extremely important group of fungi, and they take their name from the reproductive structures known as ascii. | Available |
| SNARE protein receptors and the evolution of multicellularity | There is an intriguing correlation with larger numbers of SNAREs and multicellularity, at least in plants and animals. | Unavailable |
| Dandruff, Malassezia and Candida | The presence of Malassezia does not guarantee dandruff, as this fungus is commonly present on healthy skin, but it evidently central to dandruff production if other key factors support it. | Available |
| Latex in plants and fungi | Latex is important in terms of defence not only because it typically gums-up attackers, notably insects, but often contains toxins. | Unavailable |
| Zygomycetes: convergent forms and symbioses | Zygomycete fungi show convergent evolution, and one of the most striking examples is the reproductive morphologies associated with asexual reproduction in the mucoraleans. | Unavailable |
| Mycorrhizal fungus associations with plants | One of the most important of the fungal associations is the intimate link between the majority of plants and the so-called mycorrhizal fungi. | Unavailable |
| Yeasts and yeast-like forms | We find convergences not only within the true yeasts (which belong to the ascomycetes), but much more widely, indeed even amongst the algae! | Unavailable |
| Evolution of fungicide resistance | Just as with insecticides, we see both evolution in action and also striking instances of convergence where resistance is acquired independently | Unavailable |
| Eusociality and agriculture in termites | Distinct hexamerins affect key growth hormones and help to regulate which caste type (e.g. worker or soldier) each individual develops into. | Unavailable |
| Agriculture: from ants to dugongs | Human farmers tending their fields are a familiar sight. But don't forget about those fungus-farming termites or the fish with a garden of algae… | Available |
| Agriculture in ants: leaf-cutters (attines) and non-attines | In some species, special squads leave the nest early each day, ascend the tree-trunks and then spend hours cutting out pieces of leaf that are dropped to other units on the ground. | Available |
