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By: Justin Hogan Phil Bothwell Heth

Introduction. Fungi are eukaryotic organisms that evolved over 650 million years ago, becoming one of the three dominant kingdoms of multicellular life. They usually have a thread-like body that digests food externally and transports it inside through cell walls. Fungi are key ecological participants on planet earth in that they recycle dead plants and some animals. .

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By: Justin Hogan Phil Bothwell Heth

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    1. By: Justin Hogan Phil Bothwell Heth

    2. Introduction Fungi are eukaryotic organisms that evolved over 650 million years ago, becoming one of the three dominant kingdoms of multicellular life. They usually have a thread-like body that digests food externally and transports it inside through cell walls. Fungi are key ecological participants on planet earth in that they recycle dead plants and some animals.

    3. Introduction (contd.) The organisms of the fungal lineage include mushrooms, rusts, smuts, puffballs, truffles, morels, molds, and yeasts, as well as many less well-known organisms About 70,000 species of fungi have been described; however, some estimates of total numbers suggest that 1.5 million species may exist As the sister group of animals and part of the eukaryotic crown group that radiated about a billion years ago, the fungi constitute an independent group equal in rank to that of plants and animals.

    4. Lets Look More at Fungi Rather than requiring a stomach to accomplish digestion, fungi live in their own food supply and simply grow into new food as the local environment becomes nutrient depleted. Prior to mating in sexual reproduction, individual fungi communicate with other individuals chemically via pheromones.

    5. Human use for Fungi Fungi have a long history of use by humans. Many types of mushrooms and other fungi are eaten, including button mushrooms, shiitake mushrooms, and oyster mushrooms. Many species of mushrooms are poisonous and are responsible for numerous cases of sickness and death every year Fungi are also used to produce industrial chemicals like lactic acid, antibiotics and even to make stonewashed jeans.

    6. Fungi Within their varied natural habitats fungi usually are the primary decomposer organisms present. In some low nitrogen environments several independent groups of fungi have adaptations such as nooses and sticky knobs with which to trap and degrade nematodes and other small animals Fungi are our most important plant pathogens, and include rusts, smuts, and many ascomycetes such as the agents of Dutch elm disease and chestnut blight.

    7. Structure Although fungi lack true organs, the mycelia of ascomycetes and basidiomycetes may become organized into more complex reproductive structures called fruiting bodies, or, mushrooms when conditions are right. Although these above-ground structures are the most conspicuous to humans, they make up only a small portion of the entire fungal body. Some fungi form rhizoids, which are underground root-like structures that provide support and transport nutrients from the soil to the rest of the mycelium.

    8. Structure Hyphae as seen under a log Fungi may be single-celled or multicellular. Multicellular fungi are composed of networks of long hollow tubes called hyphae. The hyphae often aggregate in a dense network known as a mycelium. The mycelium grows through the medium on which the fungus feeds. Because fungi are embedded in the medium in which they grow, they are often not visible to the naked eye.

    9. Phylogeny and classification of fungi Fungi were originally classified as plants, however they have since been separated as they are heterotrophs. The taxonomy of the Fungi is in a state of rapid flux at present, especially due to recent papers based on DNA comparisons, which often overturn the assumptions of the older systems of classification. Fungi are now thought to be more closely related to animals than to plants. For much of the Paleozoic Era, the fungi appear to be aquatic Fungi absorb their food while animals ingest it, and their cells have cell walls.

    10. Ecological Roles Along with bacteria, fungi are the major decomposers in most terrestrial (and some aquatic) ecosystems, and therefore play a critical role in biogeochemical cycles and in many food webs. Many fungi are important as partners in symbiotic relationships with other organisms

    11. More on Fungi One of the most important of these relationships are various types of mycorrhiza, which is a kind of mutualistic relationship between fungi and plants, in which the plant's roots are closely associated with fungal hyphae and other structures. Over 90% of the plant species on Earth are dependent on mycorrhizae of one type or another in order to survive, and it is hypothesized that the presence of terrestrial fungi may have been necessary in order for the first plants to colonize land. The plant donates to the fungus sugars and other carbohydrates that it manufactures from photosynthesis.

    12. Fungi The fungi also protect against diseases and pathogens and provide other benefits to the plant. Recently, plants have been found to use mycorrhizas to deliver carbohydrates and other nutrients to other plants in the same community and in some cases can make plant species that would normally exclude each other able to coexist in the same plant community.

    13. Characteristics Fungi are characterized by non-motile bodies constructed of apically elongating walled filaments, a life cycle with sexual and asexual reproduction, usually from a common thallus, haploid thalli resulting from zygotic meiosis, and heterotrophic nutrition. Spindle pole bodies, not centrioles, usually are associated with the nuclear envelope during cell division.

    14. Habitat Wherever adequate moisture, temperature, and organic substrates are available, fungi are present. Optimum conditions for growth and reproduction vary widely with fungal species. Diversity of most groups of fungi tends to increase in tropical regions, but detailed studies are only in their early stages. Gene flow appears to be restricted in many fungi. For these species large bodies of water such as the Atlantic and Pacific Oceans create barriers to gene exchange. Interesting fact: Fossil records show that fungi were present in even the coldest parts of Antarctica.

    15. The main 4 Phylum With four major branches -- Chytrids, an ancestral aquatic group – Zygomycetes, a branch that includes many of the molds – Ascomycetes, the cup fungi and true yeasts and Basidiomycetes, the mushroom-forming group, fungi provide a fascinating, diverse and often mysterious Kingdom of Life.

    16. CHYTRIDS – BEGINNINGS OF KINGDOM FUNGI Modern chytrids play a role in the decay and digestion of many aquatic animals. Chytrids are the only group of fungi with swimming spores or gametes. The flagellated cells are produced in ball-like sporangia and when released they swim off to find a new source of food.

    17. ZYGOMYCETE FUNGI – COMMON DECOMPOSERS Zygomycota formed about 500 million years ago when plants and animals begin moving onto the land. Today, zygomycetes are some of nature’s most important decomposers, and they are particularly good at breaking down animal wastes. Feces is rich in nutrients that pass right through an animal’s digestive system, so it is a good habitat for a species such as Zygomycetes.

    18. ASCOMYCOTA The ascomycete fungi probably evolved around 3-400 million years ago. This group is now very prolific, with about 30,000 known species. The group includes the cup fungi and true yeasts. Yeasts are important for their role in the production of bread, wine, beer and many other food products. Most species of ascomycetes are multicellular, rather than unicellular, and they have fruiting bodies where they reproduce sexually.

    20. BASIDIOMYCOTA The most familiar phylum in Kingdom Fungi is the Basidiomycota, the group that includes mushrooms. There are over 16 thousand species of mushrooms including some of the tastiest, and some of deadliest foods in nature. The phylum name, Basidiomycota, comes from the microscopic spore-producing structures known as basidia, a word meaning club-shaped. A single mushroom may produce millions, or even billions of spores.

    21. BASIDIOMYCOTA (continued) There are however examples of some Basidiomycota that look nothing like mushrooms - corn smut and wheat rust. Both of these fungi are parasitic on other organisms.

    22. Interesting fact/ Video Officially known as Armillaria ostoyae, or the honey mushroom, is the largest living organism on earth and was discovered in the Malheur National Forest in eastern Oregon. A fungus living three feet underground is estimated to cover 2,200 acres or 1,665 football fields and is 3.5 miles across. Experts estimate that the giant mushroom is at least 2,400 years old, but could be 7,200 years old. http://www.youtube.com/watch?v=RGp2Bw8_7sw http://www.youtube.com/watch?v=v800kU67eK0

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