Lecture 3 The Main Groups of Fungi

Presentation on theme: "Lecture 3 The Main Groups of Fungi"— Presentation transcript:

1 Lecture 3 The Main Groups of Fungi
Bio 318b Lecture 3 The Main Groups of Fungi Kingdom Chromista i) Slime moulds (not fungi) ii) Fungus-like (Oomycetes)

2 The SEVEN Kingdoms Prokaryotes (Monera) Eukaryotes Chromista Eumycota
Eubacteria Archaebacteria Prokaryotes (Monera) Eukaryotes Protozoa Chromista Protoctista (unicellular) Eumycota Fungi found here (multicellular haploids) Plantae Metazoa (Animalia) multicellular diploids

3 Fungal Kingdoms 1. Chromista. 2. Eumycota Differ in DNA sequence
- Non-fungi incl. brown algae (kelps), green algae, yellow-green algae, golden algae, diatoms, slime moulds - Fungal like species Oomycetes Differ in DNA sequence 2. Eumycota Only contains fungi. Walls of chitin, mostly no flagellae Vast majority of fungi are here. Distinguished by flagella type (one whiplash and one tinsel), often have chlorophyll c and walls made of cellulose and other materials (but not chitin). Many are unicellular.

4 One scheme for classifying Chromista
One scheme for classifying Chromista. This one leaves out the slime moulds placing them in the Protista. Fungus-like group Golden algae Diatoms Bicoecids and Slime nets Yellow-green algae Kelps (brown algae) Coccolithophorids - algae

5 Chromista Two groups have often been associated with fungi:-
1. Slime moulds - not really fungi no hyphae amoeboid phases often coenocytic - no cell walls to plasmodial stages 2. Those considered as ‘fungus-like’ hyphae contain cellulose: store food as starch Eumycota have chitin in the walls: store glycogen) have motile cells bearing flagellae hyphae are diploid

6 Some slime moulds

7 SLIME MOULDS Chromistan Fungi Phylum Myxostelida - ‘true slime moulds’
e.g. Stemonitis (Fig 2.1) and Physarum Phylum Dictyostelida - ‘cellular slime moulds’ e. g. Dictyostelium (Fig 2.2) Phylum Labyrinthulida - ‘net slime moulds’ Labyrinthula (disease of eel grass) Phylum Plasmodiophorida - ‘endoparasitic slime moulds’ e.g. Plasmodiophora (Fig 2.4) These groups are very diverse and not necessarily related

8 Myxostelida e.g. Stemonitis
Phylum Myxostelida Phylum Dictyostelida Phylum Labyrinthulida Phylum Plasmodiophorida Can see amoeboid, diploid plasmodia of these organisms in soil, ingesting bacteria etc. Form a slimy mass Some species form stalked sporangia in which meiosis occurs, giving amoeboid or biflagellate haploid spores Fuse in pairs to re-establish diploid plasmodia

9 SLIME MOULDS .Fuligo sp. (top) and Stemonites sp. (bottom)
Photos.- courtesy of Dr. G. Thorn SLIME MOULDS .Fuligo sp. (top) and Stemonites sp. (bottom)

10 Fuligo septica -Dog’s Vomit fungus
Fuligo septica -Dog’s Vomit fungus. See Tom Volk’s fungus of the month at:-

11 Physarum polycephalum
The yellow blob is a huge single cell with millions of nuclei. Its top speed is 1 mm per hour.

12 Physarum polycephalum
Slime molds cause very little damage. The plasmodium ingests bacteria, fungal spores, and maybe other smaller protozoa.

13 Physarum 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.

14 Physarum polycephalum
If the plasmodium begins to dry out too quickly or is starved, it forms a survival structure called a sclerotium The plasmodium can also produce a stalked reproductive structure containing the spores.

15 Dictyostelida e.g. Dictyostelium
Phylum Myxostelida Phylum Dictyostelida Phylum Labyrinthulida Phylum Plasmodiophorida Dictyostelida 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.

16 How 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 were 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.

17 Labyrinthulida e.g Labyrinthula
Phylum Myxostelida Phylum Dictyostelida Phylum Labyrinthulida Phylum Plasmodiophorida Labyrinthulida e.g Labyrinthula Net slime moulds Form large network or mesh of wall-less filaments L. zostera has caused huge losses to the ecologically important eelgrass habitats on salt marshes.

18 Plasmodiophorida e.g Plasmodiophora
Phylum Myxostelida Phylum Dictyostelida Phylum Labyrinthulida Phylum Plasmodiophorida Plasmodiophorida e.g Plasmodiophora obligate parasites -Examples Club root - cabbage Powdery scab - potato

19 Plasmodiophora brassicae
Club root of cabbage family Thick 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

20 Club root of cabbage Plasmodiophora brassicae
Roots of the infected plant swell greatly. Results in less growth of shoots -so reduction in yield.

21 SLIME MOULDS WEB RESOURCES. MyxoWeb Fun Facts about Fungi.
Fun Facts about Fungi. U. of California Museum of Paleontology.

22 Fungus-like Chromista
Phylum Hyphochytriomycota single anterior tinsel flagellum (B) Phylum Oomycota Two flagellae 1 whiplash, 1 tinsel (D) mastigonemes Note - one phylum in the Eumycota, the Chytridiomycota also has flagellae - just a single posterior whiplash one. (A)

23 Fungus-like Chromista
Chromistan Fungi Fungus-like Chromista Phylum Hyphochytriomycota mostly live in water or soil single cell or hyphae, sometimes develop rhizoids no known sexual stages

24 Fungus-like Chromista
Phylum Oomycota many live in water or soil some important pathogens have diploid hyphae (most other fungi have haploid hyphae) oogamous reproduction - separate antheridia and oogonia (fig 2.9). B-glucan + cellulose cell walls, (other fungi have chitin) WEB Resource.

25 Phylum Oomycota includes some important pathogenic species - often spread by aerial spores Saprolegnia - water mould on fish (fig2.10) Plasmopara - downy mildew of grape (fig 2.12) Peronospora - blue mould of tobacco, Phytophthora - late blight of potatoes Pythium - damping off disease (fig 2.11) Albugo - white rust of crucifers (cabbages etc)

26 oogonium 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 eggs antheridium oogonium

27 Asexual Reproduction Hyphae produce cells ( called sporangia) which contain many motile biflagellate zoospores Primary zoospore (only in a few species) sporangium Secondary zoospore

28 Asexual Reproduction In some plant pathogenic species (e.g. Pythium sp.) the sporangium releases a protoplasmic mass which disperses before giving rise to zoospores; In others, the sporangium itself acts as spore, germinating to produce zoospores or even in a few species directly producing hyphae. Compare life cycles of Saprolegnia, Pythium, Phytophthora, Plasmopara and Albugo

29 White rust of crucifers
Albugo candida

30 downy mildew of grape Plasmopara viticola

31 Plasmopara 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 aphid-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

32 Blue mould of tobacco Peronospora tabacina

33 a branched aerial sporangiophore of Peronospora tabacina.

34 sporangium oogonium Sporangium with sporangiospores Oomycota - Saprolegnia - an oogonium containing several eggs. Note the basal septum, and the thin-walled zones that facilitate penetration by antheridia

35 Oomycetes - 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 serious problem again.

36 See http://vassun.vassar.edu/~sttaylor/FAMINE/

37 late blight of potato Phytophthora infestans

38

39 Follow-up to lecture read Chaps. 2 and 3 text/Web/CDROM
review today’s lecture slides on Bio318b Web page check out some Web pages - e.g Tom Volk’s Fungi. Phytophthora is Tom’s ‘Fungus of the Month’ for Mar Check it out!

40 Follow-up to lecture know main groups of Chromistan fungi and how to distinguish. Important economic species key life cycles - Plasmodiophora, Saprolegnia, Pythium, Plasmopara. review terms - saprobic/parasitic; chitin/cellulose; chemotaxis. rhizoid, antheridia, oogonia, oospore, sporangium, plasmodium, whiplash, tinsel.