Kingdom Fungi

The Characteristics of Fungi Body form unicellular Multi-cellular

Mycelium – Branched Hyphae fruiting bodies both are composed of hyphae Mycelium – Branched Hyphae

The Characteristics of Fungi Heterotrophic - Saprophytes or saprobes – Symbionts - Parasites – Parasites that cause disease are called pathogens.

The Characteristics of Fungi Heterotrophic - 'other food' Saprophytes or saprobes - feed on dead tissues or organic waste (decomposers) Symbionts - mutually beneficial relationship between a fungus and another organism Parasites - feeding on living tissue of a host.  Parasites that cause disease are called pathogens.

Heterotrophic by Absorption Fungi get carbon from organic sources Hyphae release enzymes Enzymatic breakdown of substrate Products diffuse back into hyphae Enzymatic breakdown Most enzyme release (and absorption) at tips Proteins and other materials synthesized by the entire mycelium are channeled by cytoplasmic streaming to the tips of the extending hyphae. Nucleus hangs back and “directs” Products Enzymes Product diffuses back into hypha and is used

Hyphae Tubular Hard wall of chitin Grow at tips Chitin is the same material used by Arthropods (Insects, crabs, etc.) in their exoskeletonsa Nuclei of fungi are hard to see without stains

Hyphal growth Hyphae grow from their tips Mycelium = extensive, feeding web of hyphae Mycelia are the ecologically active bodies of fungi This wall is rigid Only the tip wall is plastic and stretches

Modifications of hyphae

Fungi as Saprobes and Decomposers

Fungi as Symbionts (Mutualism)

Lichens “Mutualism” between Fungus – structure Alga or cyanobacterium – provides food Thallus is a plant-like body that doesn’t have roots, stems or leaves Thallus doesn’t look like either partner Dual nature of thalli was not fully understood until early 1900’s Fungus gives the name to the lichen (by agreement) Fungus usually, but not always, an Ascomycote (in 8+ independent orders) Algae green. If bluegreen bacteria present, lichens fix nitrogen (turn atmospheric nitrogen into amino acid nitrogen in proteins)

Lichen internal structure The nature of lichen symbiosis is may also be described as mutual exploitation instead of mutual benefit. Lichens live in environments where neither fungi nor algae could live alone. While the fungi do not not grow alone in the wild, some (but not all) lichen algae occur as free-living organisms. If cultured separately, the fungi do not produce lichen compounds and the algae do not “leak” carbohydrate from their cells. In some lichens, the fungus invades algal cells with haustoria and kills some of them, but not as fast as the algae replenish its numbers by reproduction. Lobaria oregana prefers old-growth conifer canopies in forests with clean air. Lichens are nature’s biological indicators of pollution and air quality. Lobaria

Fungi as Parasites & Pathogens

Fungi are Spore-ific!!! Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin.

Reproduce by spores Formed: Directly on hyphae Fungi reproduce by releasing spores that are produced either sexually or asexually. The output of spores from one reproductive structure is enormous, with the number reaching into the trillions. Dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food. Penicillium hyphae with conidia

Hyphal growth from spore germinating spore Fungal mycelia can be huge, but they usually escape notice because they are subterranean. One giant individual of Armillaria ostoyae in Oregon is 3.4 miles in diameter and covers 2,200 acres of forest, It is at least 2,400 years old, and weighs hundreds of tons. (Actually noone has seen this of this extent – but cultures have been taken from soil over that area and all isolates have been found to be the same individual) Ten cubic centimeters of rich organic soil may have fungal hyphae with a surface area of over 300 cm2 mycelium Mycelia have a huge surface area

The Characteristics of Fungi Classified by how they reproduce. 100,000 Species (estimated 1.5 million species total). Found everywhere Cell wall present, composed of cellulose and/or chitin. Food storage - generally in the form of lipids and glycogen. Eukaryotes - true nucleus and other organelles present. All fungi require water and oxygen.

Ascomycota – “sac fungi” Sexual Reproduction – asci (sing. = ascus) - SAC Asex. Reprod. – common Cup fungi, morels, truffles Important plant parasites & saprobes Yeast - Saccharomyces Decomposers, pathogens, and found in most lichens Mycologists have described over 60,000 species of ascomycetes, or sac fungi. Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissues There is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small) Asexual reproduction by conidia (externally produced, not in sporangia) Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are Ascomycotes A cluster of asci with spores inside

Sac fungi diversity This begins the first of several photographic reviews of fungal diversity. Enjoy the pictures and try and get a feeling of some of the different forms these fungi take and their roles in the environment. http://www.youtube.com/watch?v=K9HyPxzNTPY&feature=related

Basidiomycota – “club fungi” Sexual Reproduction – basidia - CLUB Asexual reprod – not so common Rusts & smuts –plant parasites Mushrooms, puffballs Enzymes decompose wood, leaves, and other organic materials Asexual spores conidia Ecologically important on wood as decomposers and parasites Half the mushrooms form mycorrhizas SEM of basidia and spores

Bioluminescence in Mycena

Deuteromycota – Form Phylum “Imperfect Fungi” Fungi that seldom or never reproduce sexually. Asexual reproduction by vegetative growth and production of asexual spores common.

Yeasts Single celled fungi Adapted to liquids Plant saps Water films Moist animal tissues Bread and wine yeast, the budding yeast, Saccharomyces Easily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotes Thus, Saccharomyces is arguably the most important organism known to humans Candida causes diseases of humans, usually experiencing chemical imbalance or immune problems Candida Saccharomyces

Molds Rapidly growth Asexual spores Many human importances Food spoilage Food products Antibiotics, etc. Noble Rot - Botrytis A mold is a rapidly growing, asexually reproducing fungus. The mycelia of these fungi grow as saprobes or parasites on a variety of substrates. Also used in foods (Blue cheese, Tempeh) and in industrial production of drugs Early in life, a mold, a term that applies properly only to the asexual stage, produces asexual spores. Later, the same fungus may reproduce sexually, producing zygosporangia, ascocarps, or basidiocarps Some molds go through a “fake sex” process

HUMAN-FUNGUS INTERACTIONS Beneficial Effects of Fungi Decomposition - nutrient and carbon recycling. Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms).

Harmful Effects of Fungi Destruction of food, lumber, paper, and cloth. Animal and human diseases, including allergies. Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese, etc.). Plant diseases.