Filamentous Fungi Present in the External Mucus of Gizzard ...
Filamentous fungi - a background
description
Transcript of Filamentous fungi - a background
Filamentous fungi -a background
Lecture 2
Fungi are important in natureFungi are important in nature
As decomposersAs pathogens of plants, animals and humans, and in food spoilageAs producers of secondary metabolites, e. g. penicillinIn cheese, bread and wine making
Four phyla of fungiFour phyla of fungi
o Chytridiomycota - no sexual sporeo Zygomycota - zygosporeo Ascomycota - ascosporeo Basidiomycota - basidiospore
Fungal reproductionFungal reproductionAsexually, by forming conidia
Sexually (three steps):•Plasmogami (dikaryon)•Karyogami (zygote forms)•Meiosis (sexual spore forms):
•ZygosporeZygospore•AscosporeAscospore•BasidiosporeBasidiospore
ChytridiomycotaChytridiomycota
ZygomycotaZygomycota
Gametangia fuse to produce a Gametangia fuse to produce a zygospore (zygospore (Rhizopus stoloniferRhizopus stolonifer))
AscomycotaAscomycota
Ascomycota -32 300 described species
• Powdery mildews
• Nectria cankers of trees (Nectria galligena)
• Brown rot of stone fruit (Monilia fructicola)
• Chestnut blight (Cryphonectria parasitica)
• Dutch elm disease (Ophiostoma ulmi)
• Most yeasts
• Morels and truffles
Characteristics of Ascomycota• Septate hyphae• Uninucleate or multinucleate hyphae• Heterothallic or homothallic• Sexual spore = ascospore, produced in sac
called ascus. Usually 8 ascospores per ascus.
• Ascocarp (fruiting body) can be of three different types: cleistothecium, perithecium or apothecium.
Botrytis cinereaBotrytis cinerea - a fungus -causes - a fungus -causes grey moldgrey mold
Powdery mildew of cucumber
Cleistothecia of powdery mildew
Anthracnose of cucurbits
Anthracnose of Anthracnose of melon caused by melon caused by Colletotrichum Colletotrichum orbiculareorbiculare
Eye spot disease of strawberryRamularia grevilleana,
Mycosphaerella fragariae
Canker, Nectria galligena
Perithecium of Nectria galligena
PenicilliumPenicillium and and AspergillusAspergillus
Examples of Examples of
conidiophores of other conidiophores of other
imperfect fungi or imperfect fungi or
DeuteromycetesDeuteromycetes
Wilts caused by Fusarium oxysporum
Wilt of field grown melon Wilt of field grown melon caused by caused by F. ox.F. ox. formae formae speciales speciales melonismelonis
Darkened vascular Darkened vascular tissue of cucumber tissue of cucumber caused by caused by F. ox.F. ox. f.sp. f.sp. cucumerinumcucumerinum
Life cycles of fusarium wilts
Basidiomycota -22 300 described species
• Mushrooms, stinkhorns, puffballs (Basidiomycetes)
• Rusts (Teliomycetes)
• Smuts (Ustomycetes)
Basidiospores (sexual spore) made on club-Basidiospores (sexual spore) made on club-like structure, called basidium.like structure, called basidium.
BasidiomycotaBasidiomycota
Characteristics of Basidiomycota• Mycelium is septate• Septa are perforated - sometimes with
dolipore (doughnut shaped)
Characteristics of Basidiomycota• Mycelium passes two phases -
monokaryotic and dikaryotic.• Two hyphal ends of the monokaryotic
mycelium (of different mating types) fuse and produce the dikaryotic mycelium.
• The dikaryotic mycelium can divide at the apical cell and form clamp connections.
Basidiomycetes have clamp Basidiomycetes have clamp connectionsconnections
““Fairy ring”Fairy ring”
Fruiting bodies
Fly agaricFly agaric(flugsvamp)(flugsvamp)
Hallocinogenic fungi
• Mushrooms are part of many religious ceremonies in Mexico and Central America. Psilocybe mexicana is a fungus that contains the hallucinogenic drug psilocybin, which is related to LSD and mescaline.
Psilocybe mexicanaPsilocybe mexicana PsilocybinPsilocybin
Rhizoctonia solani• It is a basidiomycete;
teliomorph (Thanatephorus cucumeris) is rare.
• Has very characteristic mycelium; typical of basidiomycete.
• Differentiated into anastomosisanastomosis groups (AGAG) (fusion of hyphae only occur if same anastomosis group)
The disease cycle of Rhizoctonia solani
Characteristics of the rusts (Teliomycetes)
• Sori, in which uredospores are formed.• Were thought to be obligate parasites, but some can
be grown in the laboratory.• Can live on one host - autoecious, or two hosts -
heteroecious.• New races appear constantly; difficult to control.• Spore forms: basidiospore (n), aeciospore (n+n),
uredospore (n+n) and teliospore (2n).
Rusts
Wheat stem rustWheat stem rust ( (Puccinia Puccinia graminisgraminis))
Stem rust of wheat
Rust of roen (rönn)
Rust of raspberry
Disease cycle of cedar-apple rust
Rust of rose
Uredospores of rose rust
Teleutospores, rose rust
Corn smutCorn smut
Corn smut
Teliospores (2N)
MeiosisInfection
Mating Budding cells (1N)FilamentousDikaryon (N+N)
Chlamydospores (1N)The life cycle of smut fungiThe life cycle of smut fungi
(sexual spores)
(asexual spores)