Fungi are absorptive heterotrophsFungi are absorptive heterotrophs

Most are multicellularMost are multicellular

Kingdom: FungiKingdom: Fungi

Ecological ImportanceFungi bind soil, absorb water & breakdown detritus to recycle nutrients (decomposers)

Red algae

Green algae

Land plants

FungiChoanofla

gellates

Myxozoa

Animals

Figure 29.2

Similarities between fungi & animals

• Heterotrophs• Presence of Chitin (in some animals)

• Glycogen as storage molecule• rRNA sequence data similarities

Fungi & animals are derived fromFungi & animals are derived from a protistan lineagea protistan lineage

Fungi• Cell = HyphaHypha

• Mass of hyphae = MyceliumMycelium

• Reproductive structure (fruiting body) that makes sporesspores

Fungal Hyphae

Mycelium

Mycelium grows outward in a ringMycelium grows outward in a ring

Features of FungiFeatures of Fungi

• Cell walls of chitin• Hyphae

– Septate - with crosswalls

– Coenocytic - multinucleate

• Spores for dispersal & dormancy• Fruiting body produces spores (in some)

• Most produce no gametes (derived trait)

– Flagellated gametes (ancestral trait)

• Sex: Nuclear exchange & fusionNuclear exchange & fusion

Hyphae

Reproductivestructure

Mycelium

SeptaCell wall

Pore

926 nm

(a)

(b) Fruiting body

138 µm 3.73 µm

Hyphae: an adaptation for absorptionFungal hypha maximizes surface area to volume ratio.

Multicellular fungi are composed of hyphae

Unicellular fungi are called yeasts

Lifestyles of FungiLifestyles of Fungi

SaprobesSaprobes - decomposers - decomposers

breakdown organic molecules breakdown organic molecules

in soil or waterin soil or water

ParasitesParasites - pathogens of plants & animals- pathogens of plants & animals

MutualistsMutualists - with autotrophs- with autotrophs

MycorrhizaeMycorrhizaemyco = fungus / rhiza = root

Symbiotic mutualism+ Plant gets water & minerals+ Fungus gets sugar (food)

Western Red Cedar

Fungus presentFungus absent

Mycorrhizal fungi

Enhances plant nutrientuptake (phosphorous)

by increasing absorptive surface area of roots

Fungus wraps aroundplant roots & growsbetween or within

root cells

Ectomycorrhizae

Endomycorrhizae (VA)

LichensLichens: symbiotic mutualisms : symbiotic mutualisms between fungi & cyanobacteria or green algaebetween fungi & cyanobacteria or green algae

Types of Lichens•Crustose•Foliose•Fruiticose

phylum: Chytridomycota“Chytrids”

• Ancestral clade• Flagellated gametes (male & female)

• Unicellular or multicellular mycelia• Aquatic: most live in freshwater

phylum: Zygomycotaphylum: Zygomycota“Bread molds”“Bread molds”

AsexualReproduction:Conidia

SexualReproductionZygospore in

zygosporangium

• Coenocytic hyphae• No fleshy fruiting body

Zygomycetes

phylum: Ascomycotaphylum: Ascomycota“Sac Fungi”“Sac Fungi”

• Coenocytic w/ perforated septaeCoenocytic w/ perforated septae• Ascospores produced in sacs called asciAscospores produced in sacs called asci• Asci located in fruiting bodiesAsci located in fruiting bodies

Ascus (sac) produces 8 ascospores (4 by meiosis & 4 by mitosis)

EuascomycetesPeziza sp. = cup fungus

Asci inside of cup

Ascomycete pathogen of plantsreproducing asexually by conidia

HemiascomycetesHemiascomycetes

Yeasts are unicellular fungiYeasts are unicellular fungithat conduct that conduct fermentationfermentation

Glucose is broken down anaerobically to produce ATP:

CO2 & ethanol are by-products

Sexual reproduction• 2 haploid cells fuse• zygote undergoes meiosis (entire cell becomes an ascus)• 4 or 8 haploid cells are produced

Asexual reproductionBudding or fission

Lichen

Ascocarp

Lichen

Asexual reproduction in lichens by soridia

phylum: phylum: BasidiomycotaBasidiomycota

“Club Fungi”“Club Fungi”

• Coenocytic w/ perforated septaeCoenocytic w/ perforated septae

• Spores produced from basidiumSpores produced from basidium

Mycelia in the soil

Basidiocarp = mushroom “cap”

Gills have basidia which produce spores

1 basidium makes 4 basidiosporesby meiosis

Spores (n)

Basidiomycota

MEIOSIS

Basidium

Spores (n)germinate

to formhyphae

2n

FUSION

Hyphae of differentmating types attractHeterokaryotic mycelium

begins to grow

Maturefruiting body(n + n)

Figure 29.4c

Sexual reproduction

1. Hyphae fuse (monokaryotic hyphae)2. Exchange nuclei (heterokarytic hyphae)3. Fruiting body forms - Nuclei fuse (in basidium)4. Meiosis makes spores