Transcript Fungi
Fungi Chapter 19 Señora Ettinger Answer these questions: • How do fungi differ from other organisms? • How does the lifestyle of a fungus enable it to obtain food? • What factors make each phylum of fungi distinctive? • How do fungi affect humans? Look at page 406 of your textbook • What do you see in the main picture on this page? • Read the caption. What is really shown in the picture? • Are “fungus flowers” made of fungus? • Why would a fungus go to all the trouble of making a plant imitate a flower? Page 406 continued • Do you think this fungus hurts or helps the rock cress plant? • Would you guess that fungi could flower on its own? Characteristics of Fungi • • • • • Cell structure Lifestyle Food acquisition Habitat Cell walls Fungi—plants? • • • • Cell wall Mitosis Chlorophyll Dikaryon stage Other characteristics of Fungi • Heterotrophs • Digest food outside its body by secreted enzymes then absorb the nutrients • Typically terrestrial • Key decomposers of plant material • Most derive their nutrition from plants • Cell walls made of chitin Fungal Niches • Saprobes• Parasites• Symbiotic Mutuals Fungi Structures, page 408, draw and label figure 19-2 here: Hyphae structure, draw Figure 19-3, page 408 here: Hyphae • The dominant structure of fungi • Long, multinucleated, typically multicelled, one-cell thick fungal tissue • Typically hidden from sight since fungi grow their hyphae into their food • Serve as vascular channels along which nutrients are passed Mycelium • What is it? Septa • What is it? Septate coenocytic “Recess” Read Armillaria ostoyae Part 2: • Reproduction • Fungal Divisions Reproduction • All nuclei are haploid except for zygote nuclei (except some Chytridiomycota) • In the sexual reproduction, hyphae of two different mating strains meet and fuse but the two types of nuclei may coexist without fusion for most of the life of the fungus • Fungi reproduce by relasin spores Reproduction • Monokaryotic compartment has a single nucleus • Dikaryotic compartment has two genetically distinct nuclei – Heterokaryotic hyphae have two kinds of genetically different nuclei – Homokaryotic hyphae have genetically similar nuclei Reproductive Structures • Sporangia: • Gametangia: • Conidia Fungal Divisions • Plant-like, this groupings are called divisions instead of phyla • Presently differentiated from slime molds and water molds Chytridiomycota Fungal Divisions • • • • • Chytridiomycota Zygomycota Ascomycota Basidiomycota Deuteromycota (Fungi imperfecti) Your book doesn’t mention this one. Chytridiomycota Chytridiomycota Read • Modern Genetics Versus Ancient FrogKilling Fungus. • Write a synopsis in the space provided. • Be ready to answer questions Chytridiomycota Zygomycota Zygomycota: What does the name imply? • What does the name imply? Zygomycota some characteristics Zygomycota • Non-reproductive hyphae lack septa • Include the common bread molds • Produce zygospores Life Cycle and Sexual Reproduction • Sexual reproduction is via fusion of multinucleate gametangia • May occur between same or different mating types • Massive, haploid zygospore forms around diploid zygote nuclei • Meisois occurs during germination Asexual Reproduction • Haploid spores are produced within sporangia • Sporangium forms at the tip of erect hypha, with separating septum • Spores shed above substrate, dispersed by wind Chytridiomycota Ascomycota Ascomycota • Beneficial • Harmful forms Yeast Mold Morels True Morel False Morel Truffles Truffles Cup Fungi Chestnut Blight Chestnut Blight Dutch Elm Disease Ascomycota • Has a characteristic reproductive structure called an ascus. • A diploid zygote forms within ascus. • Asci form on ascocarp of densely interwoven hyphae Sexual Reproduction • Ascogonia are female, have trichogyne • Antheridia are male, fuse with trichogyne • Male nuclei travel to ascogonium to pair with opposite nuclei • Heterokaryotic hyphae arise from point of fusion • An ascus containing two nuclei forms at the hyphal tip Sexual Reproduction • Nuclei within the ascus fuse, forming diploid zygote which immediately undergoes meiosis • Four haploid daughter nuclei are the result. • These haploid daughter nuclei undergo mitosis to form 8 ascospores • The ascospores are then released, in most cases by the ascus bursting. Asexual Reproduction • Conidia are produced at the ends of conidiophores. Conidiophores are the stalk-like vertical growths on the hyphae. Spores are formed at the end of the conidiophores and are separated by septum and are called conidia. • The spores are released and then germinate Chytridiomycota Basidiomycota Basidiomycota • Includes mushrooms, jelly fungi, puffballs, rusts and smuts • Includes edible as well as poisonous varieties Mushrooms Mushrooms Mushrooms Jelly Fungus Jelly Fungus Puffballs Rusts Rusts Corn Smut Basidiomycota • Characteristic reproductive structure is called a basidium. • Syngamy occurs within basidium • Meiosis occurs immediately, forming four haploid basidiospores • Four basidiospores are borne on one basidium Sexual Reproduction • Spore germinates forming homokaryotic hyphae • Eventually septa form between nuclei of primary mycelium • Dikaryotic, heterokaryotic secondary mycelium forms when hyphae of different mating types fuse • Basidiocarps form of completely dikaryotic hyphae • Basidia line the gills of typical mushrooms Deuteromycota • Commonly called Fungi Imperfecti because they exhibit only asexual reproduction • Mostly ascomycetes, few zygomycetes and basidiomycetes • Many are human and plant pathogens • Others produce important chemicals such as penicillin Parasexuality • Parasexuality occurs when two different hyphae fuse forming heterokaryotic hyphae. The two different nuclei may exchange portions of chromosomes between nuclei. • Provides a certain amount of genetic recombination. Fungal Associations • Lichens • Mycorrhizae Lichens • Mostly ascomycetes with green algae and/or cyanobacterium • Specialized hyphae penetrate or envelop photosynthetic cells • Fungal chemical signals direct photosynthetic metabolism • Could be considered a form of controlled parasitism Lichens • Reproduction of the fungal portion is via normal fungal sexual reproduction • Reproduction of the photosynthetic component is asexual • The lichen as a whole can fragment and be transported by wind… to a new location to form a new individual Lichens • Can inhabit cold, dry, generally harsh environments • Help break rock surfaces and prepare habitat for other organisms • Coloration of lichen protects photosynthetic partner • Can survive adverse conditions by nearly halting metabolism Mycorrhizae • Most plant roots associated with certain fungi • Fungus aid in transfer of soil nutrients into roots • Plant provides organic carbon to fungus • Arbuscular mycorrhizae and ectomycorrhizae Arbuscular Mycorrhizae • Hyphae penetrate outer cells of root • More common mycorrhizae, generally a zygomycetes • May increase yield of crops with less energy input Ectomycorrhizae • Hyphae surround, but do not penetrate roots • Less common, mostly basidiomycetes, some ascomycetes • Characteristic symbiont of shrubs and trees Advantages • Plants more resistant to drought, cold and harsh conditions • May provide better protection against acid precipitation • Prevent accumulation of toxic metals • Speed germination of orchid seeds • Provide better growth in poor soils