Presentation on theme: "Kingdom Fungi Eukaryotic, cell walls made of chitin, saprophytic or parasitic and essential as decomposers."— Presentation transcript:
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 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 (a) Mycelium (b) Individual Hyphae (c) Hyphal Cells (cutaway) Cell Walls Septum Pore Cytoplasm Haploid Nuclei
Chytridiomycota Most live in water Have flagellated spores which move through water (unique to Chytrids)
Chytrid Filaments Male Female
Fungal Reproduction Asexual 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) Zygospore germinates Sporangia Spores (haploid) (b) Photo of Sporangia Hyphae of opposite mating types fuse to form zygospore. Haploid 1 n Diploid 2 n
Zygomycete Life Cycle (b) Hyphae of opposite mating types (+ & -) fuse. NUCLEI FUSE Diploid Zygospore formed MEIOSIS Zygospore germinates Haploid 1 n Diploid 2 n
Pilobolus: An Explosive Zygomycete on cow dung
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
Yeasts 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 Diploid 2 n Haploid 1 n Mushroom gills bear reproductive basidia. Basidia on gills Haploid Nuclei Fusion forms diploid zygote. M E I O S I S Basidiospores (haploid)
Basidiomycete Life Cycle Diploid 2 n Haploid 1 n Basidia on gills Basidiospores (haploid) “+” Mating Strain “-” Mating Strain Basidiospores germinate forming hyphae (haploid). + - Hyphae fuse, but haploid nuclei remain separate in binucleate cells Hyphae aggregate to form mushroom
Some Basidiomycetes (a) Giant Puffball (b) Shelf Fungi
A Mushroom Fairy Ring
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
The Nemesis of Nematodes – the nefarious noose fungus Special hypha with noose Unfortunate nematode
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 Association between Division Ascomycetes or Basidiomycetes, and Roots of vascular plants A mutualistic relationship