Ch. 31 Fungi

Read over zombie fungus (slide 35)

Fungi

460 MYO

heterotroph that feeds by absorption by breaking down molecules (derive nutrition)

• reproduce sexually/asexually\

• mutualistic relationship with early land plants

decomposer

break down and absorb nutrients from nonliving organic material

• EX: cellulose + lignin

Parasitic/Parasites

30% of known fungal species

absorb nutrients from living hosts

• attack food crops (10-50%) + toxic to humans

Mutualistic/Mutualists

absorb nutrients from hosts and reciprocate with actions that benefit the host

• relations with plants, algae, cyanobacteria, and animals

• Animals: digestive service breaks down plant material for cows

Yeast

multicellular filaments and single cell body structures

• enhances fungi absorption

Hyphae

branched body of fungi that has adapted for absorption

• Chitin strengthens tubular cell walls

• Septa divides hyphae with pores that allow cell-to-cell move. of organelles

Coenocytic fungi

lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei

Mycelium

Fungal hyphae form an interwoven mass

• maximizes surface-to-volume ratio, making feeding very efficient

Haustoria

specialized hyphae that allow them to extract nutrients from plants

• arbucsules exchange the nutrients with plant hosts

Ectomycorrhizal Fungi

form sheaths of hyphae over a root and typically grow into the extracellular spaces of the root cortex

Arbuscular mycorrhizal fungi

extend arbuscules through the root cell wall and into tubes formed by invagination of the plasma membrane

Mycorrhizae (mutualist)

mutually beneficial relationships between fungi and plant roots

• deliver phosphate ions and minerals to plants

• in vascular plants

• Spores: dispersed haploid cells that colonize soils for mycorrhizae

Sexual reproduction in Fungi (5)

1. Nuclei are haploid → Karyogamy produces diploid over long period

2. Hyphae fuse from different mating types

3. Pheromones to signal

4. Plasmogamy unites cytoplasm from 2 mycelia

5. Diploid → meiosis → haploid spores = genetic variation

Asexual Reproduction in Fungi (2)

Deuteromycetes

1. Molds: produce haploid spores by mitosis = visible mycelia

2. Yeasts through budding

Opisthokonts

Fungi (unicell pro: nucleariids), animals (unicell pro: choanoflagellates), and their protistan relatives

• evolved from unicellular flagellated ancestor

Phyla/Divisions of Fungi (5)

• 1.5 mil species

1.Chytrids (1000 species)

2. Zygomycetes (1000 species)

3. Glomeromycetes (160 species)

4. Ascomycetes (65,000 species)

5. Basidiomycetes (35,000 species)

Chytrids (phylum Chytridiomycota)

“little pot”

are found in terrestrial, freshwater, and marine habitats including hydrothermal vents

• decomposers, parasites, mutualists

• Zoospores: flagellated spores in chytrids

• Batrachochytrium dendrobatidis: kills amphibian species

Zygomycetes (phylum Zygomycota)

fast-growing molds, parasites, and commensal symbionts

• Black bread mold life cycle (Rhizopus stolonifer)

• Coenocytic hyphae

• Asexual sporangia = haploid spores

Zygosporangia

site of karyogamy and then meiosis

• gives zygomycetes its name

• survives unfavorable conditions

Glomeromycetes (phylum Glomeromycota)

Once considered zygomycetes but form separate clade

• form arbuscular mycorrhiza

Ascomycetes (phylum Ascomycota)

“Sac fungi”

plant pathogens, decomposers, and symbionts (can vary in complexity)

• live in marine, freshwater, and terrestrial habitats

• produce sexual spores in asci (sacs) that contained ascocarps (fruiting body)

Conidia

Ascomycetes typically reproduce asexually by enormous numbers of asexual spores

• Ascomycetes form symbiotic relations w/ green algae or cyanobacteria (lichens)

Basidiomycetes (phylum Basidiomycota)

“Club fungi”

mushrooms, puffballs, and shelf fungi that decompose wood

• form mycorrhizae or are plant parasites

• Basidium: clublike structure, diploid stage

Bassidiocarps

The dikaryotic mycelium of basidiomycete can reproduce sexually by producing fruiting bodies using sexual spores (basidiospores) in few hours

• EX: white button mushrooms or “fairy rings”

Endophytes (Mutalist)

Harmless symbiotic, fungi that live inside leaves or other plant parts

• make toxin for defense or to tolerate heat/drought + heavy metals

• Ascomycetes

Lichen

symbiotic association between a photosynthetic microorganism and a fungus that hold a mass of fungal hyphae

• EX: green algae + cyanobacteria (occupy inner layer below surface)

• Pioneer of new rock + soil surfaces

Ergot on rye/Ergotism

caused by an ascomycete, produces toxins, contain lysergic acid

• caused 40,000 death in Middle Ages

• Symptoms: gangrene, nervous spasms, burning sensations, hallucinations, and temporary insanity

Mycosis (3 types)

fungal infection in animals

• Human ex: ringworm + athlete’s foot

• Systemic ex: Coccidioidomycosis (tuberculosis)

• Opportunistic ex: Candida albicans (yeast infection)

Practical Uses of Fungi

1. cheeses, alcoholic beverages, and bread

2. Antibiotics: ascomycete Penicillium

3. Biotech: treat Parkinson’s, Huntington’s disease, diabetes, biofuels