Presentation on theme: "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."— Presentation transcript:
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?
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
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?
“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
Fungal Divisions Plant-like, this groupings are called divisions instead of phyla Presently differentiated from slime molds and water molds
Fungal Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota Deuteromycota (Fungi imperfecti) Your book doesn’t mention this one.
Read Modern Genetics Versus Ancient Frog- Killing Fungus. Write a synopsis in the space provided. Be ready to answer questions
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
Beneficial Harmful forms
Morels True MorelFalse Morel
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
Includes mushrooms, jelly fungi, puffballs, rusts and smuts Includes edible as well as poisonous varieties
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