Presentation on theme: "Lecture 3 The Main Groups of Fungi"— Presentation transcript:
1Lecture 3 The Main Groups of Fungi Bio 318bLecture 3 The Main Groups of FungiKingdom Chromistai) Slime moulds (not fungi)ii) True Fungi (Oomycetes)
2One scheme for classifying Chromista One scheme for classifying Chromista. This one leaves out the slime moulds placing them in the Protista.Golden algaeDiatomsBicoecids and Slime netsYellow-green algaeKelps (brown algae)Coccolithophorids - algae
3Chromista 1. Slime moulds - not really fungi no hyphaeamoeboid phasesoften coenocytic - no cell walls to plasmodial stages2. Those considered as fungi with motile stageshave hyphae with walls of cellulose or other non-chitin material. (The Eumycota have chitin in the walls)have motile cells bearing flagellaehyphae are diploid
7Myxostelida e.g. Stemonitis Can see amoeboid, diploid plasmodia of these organisms in soil, ingesting bacteria etc. Form a slimy massSome species form stalked sporangia in which meiosis occurs, giving amoeboid or biflagellate haploid sporesFuse in pairs to re-establish diploid plasmodia
8SLIME MOULDS .Fuligo sp. (top) and Stemonites sp. (bottom) Photos.- courtesy of Dr. G. ThornSLIME MOULDS .Fuligo sp. (top) and Stemonites sp. (bottom)
9Physarum polycephalum The yellow blob is a huge single cell with millions of nuclei. Its top speed is 1 mm per hour.
10Physarum polycephalum Slime molds cause very little damage. The plasmodium ingests bacteria, fungal spores, and maybe other smaller protozoa.
11Physarum polycephalum The millions of nuclei in a single plasmodium all divide at the same time. This makes slime molds ideal tools for scientists studying mitosis.
12Physarum polycephalum If the plasmodium begins to dry out too quickly or is starved, it forms a survival structure called a sclerotiumThe plasmodium can also produce a stalked reproductive structure containing the spores.
13Dictyostelida e.g. Dictyostelium Separate amoeba attract together ( due to cAMP which they release) - form large pseudoplasmodial ‘slug’ (an aggregation of many amoebae rather than a true plasmodium).This then elongates vertically and releases new amoebae.
14How do the amoebae find each other to aggregate ? Not done by "leader" amoebae. Instead each amoeba pumps out a chemical that leaves an invisible trail. Other amoebae cross the trail, follow it and strengthen it More amoebae are attracted by the stronger concentration till eventually all of the amoebae gather themselves into a pseudoplasmodium.What’s the connection between slime moulds and video games ?- Mathematical equations written to explain slime mold aggregation changed slightly and used in the programming of action figures in video games. Equations have also used in program StarLogo which mimics the activities of groups such as ant colonies and flocks of birds, whose orderly patterns of activity also occur without the direction of a leader.
16Plasmodiophora brassicae Club root of cabbage familyThick walled resting spores release zoospores - find new host by chemotaxis - encyst - inject protoplast into root hair. These form plasmodia inside root hair - release zoospores - infect root cortical cells - form large secondary plasmodia - meiosis - resting spores
17Club root of cabbage Plasmodiophora brassicae Roots of the infected plant swell greatly. Results in less growth of shoots -so reduction in yield.
18True Fungi - Chromista Phylum Hyphochytriomycota Phylum Oomycota single anterior tinsel flagellum (B)Phylum OomycotaTwo flagellae1 whiplash, 1 tinsel (D)mastigonemesNote - one phylum in the Eumycota, the Chytridiomycota also has flagellae - just a single posterior whiplash one. (A)
19True Fungi Phylum Hyphochytriomycota Chromistan Fungi mostly live in water or soilsingle cell or hyphae, sometimes develop rhizoidsno known sexual stages
20True Fungi in Chromista Phylum Oomycotamany live in water or soilsome important pathogenshave diploid hyphae (most other fungi have haploid hyphae)oogamous reproduction - separate antheridia and oogonia (fig 2.9).cellulose cell walls, (other fungi have chitin)WEB Resource.
21Phylum Oomycotamany important pathogenic species - often spread by aerial sporesSaprolegnia - water mould on fish (fig2.10)Plasmopara - downy mildew of grape (fig 2.12)Peronospora - blue mould of tobacco,Phytophthora - late blight of potatoesPythium - damping off disease (fig 2.11)Albugo - white rust of crucifers (cabbages etc)
22oogonium with several eggs Hyphae are diploid - meiosis occurs in the antheridia and oogonia to produce haploid nuclei. Fusion of antheridium nuclei with oospores in oogonium restores diploid state.oogonium with several eggsantheridium oogonium
25Plasmopara viticola, the downy mildew of grapes. A native of North America, in the late 1870s it was accidentally introduced to Europe at a time when the French wine industry was concerned over a massive aphid infestation.They brought resistant vine strains over from America to graft their roots onto their own grapes. However, these American stocks also brought the downy mildew which almost wiped out the entire French wine industry.The industry was saved by the serendipitous discovery of Bordeaux mixture, a mixture of lime and copper sulfate,This discovery is also important for being the first known fungicide, and in fact the first chemical used to control a plant disease
27a branched aerial sporangiophore of Peronospora tabacina.
28Oomycetes - late blight of potato - Phytophthora infestans Created havoc in Europe e.g wiped out Irish potato crop - sole food of many poor people. Caused more than 1 million deaths - 3 million to emigrate - America.Heterothallic sp. But until 1976 only 1 mating-type in anywhere except Mexico - its origin - so was asexual.Since then, other mating-type has arrived and sexual reproduction has started - so disease becoming a problem again.
32Follow-up to lecture read Chaps. 2 and 3 text/Web/CDROM review today’s lecture slides on Bio318b Web pagecheck out some Web pages - e.g Tom Volk’s Fungi.
33Follow-up to lectureknow main groups of Chromistan fungi and how to distinguish.Important economic specieskey life cycles - Plasmodiophora, Saprolegnia, Pythium, Plasmopara.review terms -saprobic/parasitic; chitin/cellulose; chemotaxis.rhizoid, anisogamy, antheridia, oogonia, oospore, sporangium, plasmodium, whiplash, tinsel, eucarpic, holocarpic.