Fungus Chapter 31

What you need to know! The characteristics of fungi The characteristics of fungi Important ecological roles of fungi in mycorrhizal associations, and as decomposers and parasitic plant pathogens Important ecological roles of fungi in mycorrhizal associations, and as decomposers and parasitic plant pathogens

Kingdom Fungi Phylum: Myxomycota (slime molds) Phylum: Myxomycota (slime molds) Phylum: Eumycota (true fungi) Phylum: Eumycota (true fungi) class: Phycomycetes class: Phycomycetes class: Glomeromycetes class: Glomeromycetes class: Ascomycetes class: Ascomycetes class: Basidiomycetes class: Basidiomycetes Domain Eukarya

Fungi are eukaryotes and most are multicellular. Fungi are eukaryotes and most are multicellular. Fungi are heterotrophic Fungi are heterotrophic Animals (not plants) are the closest relatives of fungi. Animals (not plants) are the closest relatives of fungi. Characteristics

One of the two major decomposers in the environment: fungi (bacteria is the other) One of the two major decomposers in the environment: fungi (bacteria is the other) decompose dead organisms (fallen leaves, feces, dead bodies, other organic materials) decompose dead organisms (fallen leaves, feces, dead bodies, other organic materials) Recycles vital chemical elements back to the environment Recycles vital chemical elements back to the environment Many plants depend on mutualistic fungi that help their roots absorb minerals and water from the soil. Many plants depend on mutualistic fungi that help their roots absorb minerals and water from the soil. Humans cultivate fungi to produce antibiotics and other drugs, to make bread rise (yeast), and to ferment beer and wine (yeast). Humans cultivate fungi to produce antibiotics and other drugs, to make bread rise (yeast), and to ferment beer and wine (yeast). Role in the Environment

Fungi acquire their nutrients by absorption. Fungi acquire their nutrients by absorption. Exoenzymes, powerful hydrolytic enzymes secreted by the fungus, digest food outside its body to simpler compounds that the fungus can absorb and use. Exoenzymes, powerful hydrolytic enzymes secreted by the fungus, digest food outside its body to simpler compounds that the fungus can absorb and use. Some exoenzymes attack the digestive system (toxic to humans) Some exoenzymes attack the digestive system (toxic to humans) They absorb small organic molecules from the surrounding medium. They absorb small organic molecules from the surrounding medium. Some fungi can digest lignin (wood) growing in forests Some fungi can digest lignin (wood) growing in forests Some contain chemicals that act as hallucinogens Some contain chemicals that act as hallucinogens Decomposers and Symbiots

Extensive surface area and rapid growth adapt fungi for absorptive nutrition Extensive surface area and rapid growth adapt fungi for absorptive nutrition The vegetative bodies of most fungi are constructed of tiny filaments called hyphae that form an interwoven mat called a mycelium. The vegetative bodies of most fungi are constructed of tiny filaments called hyphae that form an interwoven mat called a mycelium. Structure

Fungal mycelia can be huge, but they usually escape notice because they are subterranean. 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, 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. It is at least 2,400 years old, and weighs hundreds of tons. Fungal hyphae have cell walls. Fungal hyphae have cell walls. These are built mainly of chitin, a strong but flexible nitrogen-containing polysaccharide, identical to that found in arthropods. These are built mainly of chitin, a strong but flexible nitrogen-containing polysaccharide, identical to that found in arthropods. Structure

Most fungi are multicellular with hyphae divided into cells by cross walls, or septa. Most fungi are multicellular with hyphae divided into cells by cross walls, or septa. These generally have pores large enough for ribosomes, mitochondria, and even nuclei to flow from cell to cell. These generally have pores large enough for ribosomes, mitochondria, and even nuclei to flow from cell to cell. Fungi that lack septa (coenocytic fungi) consist of a continuous cytoplasmic mass with hundreds or thousands of nuclei. Fungi that lack septa (coenocytic fungi) consist of a continuous cytoplasmic mass with hundreds or thousands of nuclei. This results from repeated nuclear division without cytoplasmic division. This results from repeated nuclear division without cytoplasmic division. Structure

Parasitic fungi usually have some hyphae modified as haustoria, nutrient-absorbing hyphal tips that penetrate the tissues of their host. Parasitic fungi usually have some hyphae modified as haustoria, nutrient-absorbing hyphal tips that penetrate the tissues of their host. Some fungi even have hyphae adapted for preying on animals. Some fungi even have hyphae adapted for preying on animals. Parasitic Fungi

Fungi reproduce by releasing spores (n) that are produced either sexually or asexually. Fungi reproduce by releasing spores (n) that are produced either sexually or asexually. Distributed by wind, water Distributed by wind, water The nuclei of fungal hyphae and spores of most species are haploid, except for transient diploid stages that form during sexual life cycles. The nuclei of fungal hyphae and spores of most species are haploid, except for transient diploid stages that form during sexual life cycles. However, some mycelia become genetically heterogeneous –heterokaryotic mycelium- through the fusion of two hyphae that have genetically different nuclei (sordaria) However, some mycelia become genetically heterogeneous –heterokaryotic mycelium- through the fusion of two hyphae that have genetically different nuclei (sordaria) Reproduction Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

In many fungi with sexual life cycles, karyogamy, fusion of haploid nuclei contributed by two parents (sordaria), occurs well after plasmogamy, cytoplasmic fusion by the two parents. In many fungi with sexual life cycles, karyogamy, fusion of haploid nuclei contributed by two parents (sordaria), occurs well after plasmogamy, cytoplasmic fusion by the two parents. Fig. 31.3Reproduction

Phylum: Myxomycophyta (slime molds) Sometimes placed with protists Sometimes placed with protists Enormous single cells with thousands of nuclei Enormous single cells with thousands of nuclei They swarm together and build fruiting bodies for reproduction using chemical markers They swarm together and build fruiting bodies for reproduction using chemical markers

Black bread mold Black bread mold Penicillium Penicillium Class: Phycomycetes-Molds

Glomeromycetes Symbiotic root fungi - Mycorrhizae Symbiotic root fungi - Mycorrhizae Lichens: algae + fungi body Lichens: algae + fungi body

Class: Ascomycota – Sac Fungi Yeast, truffles, sordaria, and ringworm Yeast, truffles, sordaria, and ringworm Ergots on wheat – highly toxic Ergots on wheat – highly toxic Contains Lysergic acid: 40,000 died in 944 in an Epidemic in Europe Contains Lysergic acid: 40,000 died in 944 in an Epidemic in Europe

Class: Basidiomycota-(mushrooms) Mushrooms, shrooms, shelf fungi, puffballs, etc. Mushrooms, shrooms, shelf fungi, puffballs, etc. May be edible or toxic May be edible or toxic Depends on the enzymes they have Depends on the enzymes they have