fungi lab. tentative phylogeny fig 28.8 generalized fungal lifecycle spore-producing structures...
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Fungi Lab
Tentative Phylogeny Fig 28.8
Generalized fungal lifecycle
Spore-producingstructures
Spores
ASEXUALREPRODUCTION
GERMINATION
ZygoteMycelium
GERMINATIONMEIOSIS
Spore-producingstructures
Spores
Key
Haploid (n)
Heterokaryotic(unfused nuclei fromdifferent parents)
Diploid (2n)
PLASMOGAMY(fusion of cytoplasm)
Heterokaryoticstage
KARYOGAMY(fusion of nuclei)
SEXUALREPRODUCTION Zygote
Mycelium
Phylogeny of fungiChytrids
Zygote fungi
Arbuscular mycorrhizal
fungi
Sac fungi
Club fungi
Chy
trid
iom
ycot
a
Zyg
omyc
ota
Glo
mer
om
ycot
a
Asc
omyc
ota
Bas
idio
myc
ota
Fungal Divisions Chytridyomycota – • Aquatic, with flagellated zoospores• Diploid phase- sporophyte Zygomycota = zygospores.• Resistant zygote sporangiumGlomeromycota= zygospores• arbuscular mycorrhizae.Ascomycota = ascospores• Endogenous meiosporesBasidiomycota = basidiospores• Exogenous meiosporesDeuteromycetes – imperfect,• no sexual reproduction
Chytridiomycota• Chytrids use an absorptive mode of nutrition and have
chitin cell walls.• There are a few unicellular chytrids, but most form
ceonocytic hyphae.• Chytrids share key enzymes and metabolic pathways
with other fungal groups, but not with the slime molds• Ancestral to
other three groups on land
• Forms flagellated zoospores
Allomyces Life cycle
#13
#14
Diploid
Haploid
Allomyces gametophyte (n) slide
Gametophyte
SporophyteMeiosporangia
Allomyces (2n) Fresh Sample
Fungal Divisions Chytridyomycota – • Aquatic, with flagellated zoospores• Diploid phase- sporophyte Zygomycota = zygospores.• Resistant zygote sporangiumGlomeromycota= zygospores• arbuscular mycorrhizae.Ascomycota = ascospores• Endogenous meiosporesBasidiomycota = basidiospores• Exogenous meiosporesDeuteromycetes – imperfect,• no sexual reproduction
Zygomycete lifecycle
#16
#15
Zygosporangium formation
• +, - suspensor hyphae grow together.
• Each tip cuts off a gametangia with complete septa.
• Gametangia fuse into one large heterokaryont.
• Nuclei pair up form many diploid nuclei.
• Resistant wall forms on Zygosporangium
• Before germination meiosis takes place
• Forms sporangia, releasing haploid spores
Asexual Spore formation
• Haploid nuclei migrate to swollen hyphal tip.
• Hyphal tip forms complete septum, now a sporangium.
• Each nucleus forms a spore around itself with cytoplasm, endospores.
• Sporangium wall breaks.• Spores blow away.
Phycomyces
suspensors
Phycomyces on low power
Zygosporangia
Phycomyces
Gametangia fusing
Pilobolus
Sporangium with mitospores
Swollen sprangiophore
Spore dispersal
Positive Phototropism
Fungal Divisions Chytridyomycota – • Aquatic, with flagellated zoospores• Diploid phase- sporophyte Zygomycota = zygospores.• Resistant zygote sporangiumGlomeromycota= zygospores• arbuscular mycorrhizae.Ascomycota = ascospores• Endogenous meiosporesBasidiomycota = basidiospores• Exogenous meiosporesDeuteromycetes – imperfect,• no sexual reproduction
• Mycologists have described over 60,000 species of ascomycetes, or sac fungi.
• They range in sizeand complexityfrom unicellularyeasts to
elaboratecup fungi andmorels.
Ascomycota: Sac fungi produce sexual spores in saclike asci
Ascomycetes are characterized by an extensive heterokaryotic stage during the formation of ascocarps.
Fig. 31.10
Ascus formation• Hyphal tip makes complete septum,
Nuclei fuse – a single 2n nucleus• Meiosis – 4 haploid nuclei• One mitotic division – 8 haploid nuclei• Each nucleus cuts off some cytoplasm and
forms new wall, inside original hyphae wall.• 8 ascospores are forcibly ejected by osmotic
pressure.• Different forms of ascocarp have evolved.
Ascospore formation
Zygote Meiosis
MitosisSpore wall
N+N
Peziza sp.
apothecia
Apothecia- #18
Asci – Slide #18
Morchella sp.
Morchella x-section
Morchella slide
Sordaria-perithecia
Sordaria slide #
Fresh Sordaria slide
Saccharomyces cervisea
Budding
Conidia• Many Ascomycetes reproduce asexually by
producing enormous numbers of Conidia, asexual spores, (exogenous mitospores) which are usually dispersed by the wind.
Conidiophore continuously divides forming more spores at tip.
Fungal Divisions Chytridyomycota – • Aquatic, with flagellated zoospores• Diploid phase- sporophyte Zygomycota = zygospores.• Resistant zygote sporangiumGlomeromycota= zygospores• arbuscular mycorrhizae.Ascomycota = ascospores• Endogenous meiosporesBasidiomycota = basidiospores• Exogenous meiosporesDeuteromycetes – imperfect,• no sexual reproduction
Basidiomycota• Typical Mushroom• Almost no asexual reproduction• Many mycorrhizae species• Oldest organism ?
Mushrooms caps have basidia on gills.
The spores drop beneath the cap and are blown away.
• The life cycle of a Basidiomycete usually includes a long-lived dikaryotic mycelium.
Fig. 31.12
Basidia formation
Coprinus
Basidiospores
Lichens • Symbiosis of
– Phycobiont, algae / cyanobacteria – Mycobiont - fungi.
• Not individual organisms • Primary colonizers of new land in
succession, and in tundra areas• Soredia asexually reproduce lichen
– Fungi often reproduce on their own.
• Lichen acids, dyes
Fig. 31.17
Three growth forms:1. Crustose – flat on
stones2. Foliose- leaf-like as
in picture3. Fruticose- upright
growing
Phycobiont in inner layers protected by fungi on top and bottom
(a) A fruticose (shrub-like) lichen
(b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichens
Physcia # 28
Ascocarp
Phycobiont
Umbilicaria sp.
Upper Cortex
Phycobiont layer
Filamentous Hyphal layermedulla
Lower Cortex
Glomeromycota
• Has some characteristics similar to zygomycetes.
• DNA comparisons show then to be their own group
• Form Arbscular endomycorrhizae
Endotropic Mycorrhizae
Arbuscular mycorrhizae2.5 m
Plant cell wall