Kingdom Fungi Eukaryotic, cell walls made of chitin, saprophytic or parasitic and essential as decomposers.

The body of a fungus is called the mycelium The body of a fungus is called the mycelium. The mycelium is composed of hyphae, which are hair-like filaments. They are usually haploid or 1N. The reproductive structures are the part of the fungus that you usually see (ex. mushroom). These structures produce spores either asexually by mitosis or sexually by meiosis. The names of the four divisions of fungi are related to the shape of their sporangiophores or lack thereof.

The Filamentous Body of a Fungus (c) Hyphal Cells (cutaway) (a) Mycelium Haploid Nuclei Cytoplasm (a) A fungal mycelium spreads over decaying vegetation. The mycelium is composed of (b) a tangle of microscopic hyphae, only one cell thick, (c) portrayed in cross section to show their internal organization. Septum (b) Individual Hyphae Pore Cell Walls

Phyla of Fungi Chytridiomycota – chytrids Zygomycota – zygote fungi Ascomycota – sac fungi Basidomycota – club fungi Deuteromycota – imperfect fungi

Chytridiomycota Most live in water Have flagellated spores which move through water (unique to Chytrids)

Chytrid Filaments Male Female These filaments of the chytrid fungus Allomyces are in the midst of sexual reproduction. The orange structures visible on many of the filaments will release male gametes; the clear structure will release female gametes. Chytrid gametes are flagellated, and these swimming reproductive structures aid dispersal of members of this mostly aquatic phylum. Female

Fungal Reproduction Asexual Sexual Fragmentation Continuation of haploid cells by mitosis Sexual Fusion of two haploid nuclei Diploid zygotes Ultimately produce haploid sexual spores Germinate to produce haploid mycelium

Division Zygomycota = bread molds This is the most primitive type of fungus. The hyphae are multinucleate, without separate cells or cell walls. Lots of sporangiophores with sporangia are produced that asexually make spores by mitosis. Occasionally two hyphae will fuse. One (-) and one (+) and a 2N zygosporangium is formed. This zygosporangium is capable of withstanding harsh conditions. The DNA in it will undergo meiosis to produce a 1N nucleus which then grows into an asexually reproducing sporangiophore. The most common example is Rhizopus nigricans, the common black bread mold.

Zygomycete Life Cycle (a) Spores (haploid) Sporangia (a) Top: During asexual reproduction in the black bread mold (genus Rhizopus), haploid spores, produced within (b) sporangia, disperse and germinate on food such as bread. The resulting haploid hyphae may complete the asexual cycle by producing sporangia and spores. Diploid 2n Zygospore germinates Haploid 1n Hyphae of opposite mating types fuse to form zygospore. (b) Photo of Sporangia

Zygomycete Life Cycle (b) Hyphae of opposite mating types (+ & -) fuse. Zygospore germinates (a) Top: During asexual reproduction in the black bread mold (genus Rhizopus), haploid spores, produced within (b) sporangia, disperse and germinate on food such as bread. The resulting haploid hyphae may complete the asexual cycle by producing sporangia and spores. NUCLEI FUSE MEIOSIS Diploid 2n Diploid Zygospore formed Haploid 1n

Pilobolus: An Explosive Zygomycete on cow dung The delicate, translucent reproductive structures of the zygomycete Pilobolus will literally blow their tops when ripe, dispersing the black caps with their payload of spores.

Division Ascomycota = the sac fungi Ascocarps contain asci. Within each ascus are eight ascospores. Four were made by meiosis and the number was doubled by mitosis. This is the sexual structure of this division. These fungi also reproduce asexually with spores called conidia. Common examples are yeast, Sordaria, truffles, morels, Peach leaf curl and cup fungi. Yeast are the oddballs out of this group. They have grown to exist without hyphae and reproduce asexually by budding.

Each sac contains 8 ascospores ex.Sordaria

Some Ascomycetes (a) Scarlet Cup Fungus (b) Morel (a) The cup-shaped fruiting body of the scarlet cup fungus (b) The morel, an edible delicacy. (Consult an expert before sampling any wild fungus—some are deadly!) (b) Morel

Truffles Truffles, rare ascomycetes (each about the size of a small apple), are a gastronomic delicacy.

Yeasts Yeasts are unusual, normally nonfilamentous ascomycetes that reproduce most commonly by budding. The yeast shown here is Candida, a common cause of vaginal infections. Candida sp.

Ascus Vs. Basidium

Division Basidiomycota = club fungi The most common state for this fungus is an N + N stage called dikaryogamy. It occurs after a (+) and a (-) hyphae fuse. The nuclei, however, do not fuse, and new N+N cells are made into a reproductive structure such as the mushroom. A basidiocarp contains thousands of basidia which produce spores sexually by meiosis. Karyogamy, when the two nuclei fuse, occurs immediately before meiosis. Examples of basidiomycetes are puffballs, mushrooms, shelf fungi, rusts and smuts.

Basidia with basidiospores = club shaped

Basidiomycete Life Cycle Haploid Nuclei Fusion forms diploid zygote. Basidia on gills The mushroom (top left) is a reproductive structure formed from aggregated hyphae made up of cells that each contain two haploid nuclei. Within the cap, leaflike gills bear numerous basidia (top right). Within each basidium, the two haploid nuclei fuse, producing a diploid zygote. The zygote then undergoes meiosis, forming haploid basidiospores that are released from the basidia (right). After dispersal by wind or water, the basidiospores germinate, forming haploid hyphae. When hyphae of different mating types meet, some of the cells fuse. These cells, each containing two haploid nuclei, produce an extensive underground mycelium (bottom). Under appropriate conditions, portions of the mycelium aggregate, swell, and differentiate, poking up through the soil as mushrooms and completing the cycle. MEIOSIS Basidiospores (haploid) Haploid 1n Mushroom gills bear reproductive basidia. Diploid 2n

Basidiomycete Life Cycle Basidiospores (haploid) Basidia on gills Hyphae aggregate to form mushroom The mushroom (top left) is a reproductive structure formed from aggregated hyphae made up of cells that each contain two haploid nuclei. Within the cap, leaflike gills bear numerous basidia (top right). Within each basidium, the two haploid nuclei fuse, producing a diploid zygote. The zygote then undergoes meiosis, forming haploid basidiospores that are released from the basidia (right). After dispersal by wind or water, the basidiospores germinate, forming haploid hyphae. When hyphae of different mating types meet, some of the cells fuse. These cells, each containing two haploid nuclei, produce an extensive underground mycelium (bottom). Under appropriate conditions, portions of the mycelium aggregate, swell, and differentiate, poking up through the soil as mushrooms and completing the cycle. “+” Mating Strain “-” Mating Strain Basidiospores germinate forming hyphae (haploid). + - Haploid 1n Hyphae fuse, but haploid nuclei remain separate in binucleate cells Diploid 2n

Some Basidiomycetes (a) Giant Puffball (b) Shelf Fungi The giant puffball Lycopedon giganteum may produce up to 5 trillion spores. Shelf fungi, the size of dessert plates, are conspicuous on trees. (a) Giant Puffball (b) Shelf Fungi

A Mushroom Fairy Ring Mushrooms emerge in a fairy ring from an underground fungal mycelium, growing outward from a central point where a single spore germinated, perhaps centuries ago.

Corn Smut This basidiomycete pathogen destroys millions of dollars’ worth of corn each year. Even a pest like corn smut has its admirers, though. In Mexico this fungus is known as huitlacoche and is considered to be a great delicacy.

Deuteromycetes – imperfect fungi Category is not based on homologous structures or evolutionary relationships but is based on the fact that no known sexual structure has been observed. Reproduce asexually with spore producing conidiospores. Examples – athlete’s foot, ringworm, the nefarious noose fungus, the lethal lollipop fungus, Penicillium, and Candida albicans which causes yeast infections and thrush

Penicillium Penicillium growing on an orange. Reproductive structures, which coat the fruit’s surface, are visible, while hyphae beneath draw nourishment from inside. The antibiotic penicillin was first isolated from this fungus.

The Nemesis of Nematodes – the nefarious noose fungus Arthrobotrys, the nematode (roundworm) strangler, traps its nematode prey in a nooselike modified hypha that swells when the inside of the loop is contacted. Unfortunate nematode Special hypha with noose

Conidia with conidiospores – any asexually spore producing stem is called a conidia. The following are both pictures of Penicillium

Rhizopus, Penicillium, and Aspergillus The three pictures on the right are Rhizopus(zygomycete), the picture with the orange background is Penicillium(deuteromycete) and the bottom, right picture is Aspergillus(ascomycete).

Ecological Impact of Fungi Symbiotic relationships Lichens Association between Division Ascomycetes, and Unicellular green algae or Cyanobacteria Pioneers in succession Mycorrhizae Division Ascomycetes or Basidiomycetes, and Roots of vascular plants A mutualistic relationship

Lichens: Symbiotic Partnerships Algal Layer Most lichens have a layered structure bounded on the top and bottom by an outer layer formed from fungal hyphae. Attachments formed from fungal hyphae emerge from the lower layer and anchor the lichen to a surface, such as a rock or a tree. An algal layer in which the alga and fungus grow in close association lies beneath the upper layer of hyphae. Fungal Hyphae Attachment Structure

Lichens Covering a Rock A colorful encrusting lichen, growing on dry rock, illustrates the tough independence of this symbiotic combination of fungus and alga.

Fructicose, Foliose, and Crustose lichens

Mycorrhizae Enhance Plant Growth Hyphae of mycorrhizae entwining about the root of an aspen tree. Plants grow significantly better in a symbiotic association with these fungi, which help make nutrients and water available to the roots. Mycorrhizae