BIOL 112: The Fungi PDF

BIOL 112 The Fungi  General Characteristics ⚫ Mostly multicellular and terrestrial ⚫ Absorptive heterotrophs (small organics & minerals): saprobes, parasites or mutualists ⚫ Cell walls composed of chitin ⚫ Reproduce either sexually or asexually by spores  Reproductive structur...

BIOL 112 The Fungi  General Characteristics ⚫ Mostly multicellular and terrestrial ⚫ Absorptive heterotrophs (small organics & minerals): saprobes, parasites or mutualists ⚫ Cell walls composed of chitin ⚫ Reproduce either sexually or asexually by spores  Reproductive structure Hyphae Spore-producing structures 60 μm Mycelium (a mass of hyphae) Hyphae Structure  The Mycelium ⚫ Extensive hyphal growth produces a mycelium ⚫ Mycelia are either on soil surface or other objects or grow below the soil ⚫ A single mycelium can cover 100s of acres of area with thousands of miles of hyphae! ⚫ Hyphal growth is key to increased absorption due to increased surface area General Fungal Life Cycle  May persist & divide for years Typical Cycle Common in changing environment Very brief →  Animals (and their close protistan relatives Opisthokonts UNICELLULAR, FLAGELLATED Nucleariids ANCESTOR Fungi Chytrids Other fungi  Origins of Fungi ⚫ DNA evidence suggests that – Fungi are most closely related to unicellular nucleariids – Animals are most closely related to unicellular choanoflagellates ⚫ This suggests that multicellularity arose separately in animals and fungi ⚫ The oldest undisputed fossils of fungi are only about 460 million years old  Early-Diverging Fungal Groups ⚫ Genomic studies have identified chytrids in the genus Rozella as an early diverging fungal lineage ⚫ Rozella and other members of the unicellular group, “cryptomycota” lack chitin-rich cell walls ⚫ Fungi were among the earliest colonizers of land Chytrids (1,000 species) Hyphae 25 μm Zygomycetes (1,000 species) Glomeromycetes (160 species) Fungal hypha 25 μm Ascomycetes (65,000 species) Basidiomycetes (30,000 species)  Zygomycota – Zygote Fungi ⚫ Mostly terrestrial, on soil or detritus ⚫ Some are mycorrhizae are mutualists on plant roots ⚫ Coenocytic hyphae, except where reproductive cells are formed ⚫ Zygosporangia are extremely resistant to environmental conditions Rhizopus on Orange Peel Progametangium Rhizopus Zygosporangium Arbuscular Mycorrhizae Chytrids Zygomycetes Glomeromycetes Ascomycetes Basidiomycetes  Ascomycota – Sac Fungi ⚫ Marine, freshwater, terrestrial ⚫ Yeast, cup fungi, truffles, morels ⚫ Saprobes, plant pathogens, mutualists (lichens or mycorrhizae) ⚫ Dikaryotic hyphae form ascocarps ⚫ Sexual spores borne in asci on ascocarps ⚫ Asexual spores borne in “naked” groups on hyphae Aleuria aurantia Sarcoscypha coccinea Urnula Tuber gibbosum - Truffles Morchella - morels Gyromitra esculenta – False Morel Chytrids Zygomycetes Glomeromycetes Ascomycetes Basidiomycetes  Basidiomycota – Club Fungi ⚫ Mostly terrestrial; saprobes or plant parasites ⚫ Mushrooms, shelf fungi, puffballs, rusts ⚫ Septate hyphae ⚫ Basidiocarps, the dikaryotic fruiting body, is the prominent, visible stage in the life cycle ⚫ Spores are borne in basidia on basidiocarp, often on gills beneath the cap Agaricus sylvicola Agaricus campestris Amanita muscaria – Fly Agaric Amanita virosa – Destroying Angel Hericium erinaceus – Coral Mushroom Phallus raveneli  Unique Lifestyles in Fungi ⚫ Molds ⚫ Yeasts ⚫ Lichens ⚫ Mycorrhizae  Molds ⚫ Rapid growing, asexually reproducing, saprobes or parasites ⚫ Fungi imperfecti – No known sexual stage in life cycle – Penicillium has had economic importance as antibiotic source and in cheese making – long placed in fungi imperfecti, now in Ascomycota Penicillium Sporangia  Yeasts ⚫ Unicellular (sometimes forms mycelium), perfect and imperfect ⚫ Economic uses – Bread making – Alcohol production ⚫ Candida (Ascomycota) can cause yeast infections in humans – thrush in babies, vaginal infections  Lichens ⚫ A symbiotic relationship of fungus and algae or cyanobacteria ⚫ Generally ascomycetes, sometimes basidiomycetes ⚫ A “balance” of power relationship ⚫ Important pioneer species in primary succession ⚫ Very hardy and can survive desiccation Fruiticose Lichen Foliose Lichen Crustose Lichens  Mycorrhizae ⚫ Fungi from all 3 main divisions that are mutualistic with vascular plants ⚫ Hyphae penetrate roots, and sometimes even cells (Glomeromycetes) ⚫ Aid plant in mineral uptake, receive organic molecules in return ⚫ Some plants cannot survive without mycorrhizae ⚫ Mushrooms beneath trees are typically the fruiting bodies of mycorrhizae Endomycorrhizae in Corn Root Vesicles and intracellular hyphae Ectomycorrhizae  Importance of Fungi ⚫ Decomposition of detritus ⚫ Pathogens ⚫ Food for animals and humans  Fungal Phylum Distinguishing Features Chytridiomycota Flagellated spores (chytrids) Zygomycota Resistant zygosporangium (zygomycetes) as sexual stage Glomeromycota Arbuscular mycorrhizae (arbuscular formed with plants mycorrhizal fungi) Ascomycota Sexual spores (ascospores) (ascomycetes) borne internally in sacs called asci; vast numbers of asexual spores (conidia) produced Basidiomycota Elaborate fruiting body (basidiomycetes) (basidiocarp) containing many basidia that produce sexual spores (basidiospores)