Fungi (Topic 4)

Unicellular, flagellated ancestor

Opisthokonta Derived Trait

470 mya

Fungi colonized \~___ ___ (before plants!)

Characteristics of Fungi

* mostly haploid lifecycle
* no photosynthesis
* heterotrophs - digest externally through hydrolases
* cell wall contains chitin

Body structure of fungi

can either be…

* single celled
* yeasts only
* multicellular
* ==mycelium== (pl. mycelia) = fungal body that grows in & around food source
* ==hyphae== = long branched filaments

Mycelium

Fungal body that grows in & around food source

Hyphae

Long branched filaments

Hyphae functions

* Structure
* Feeding
* Predatory
* Mutualistic
* like ==haustoria== found in ==mycorrhizae==
* Reproductive
* ==Aerial hyphae==: aids in spore dispersal
* ==Fruiting bodies==: multicellular, complex
* ie: mushrooms

Haustoria

Penetrate plant tissue - parasitic or mutualistic

Mycorrhizae

Mutualism between fungi and plant root

Spore

* A single cell
* Starts a new individual with haploid
* In sexual OR asexual reproduction of fungi
* dispersed by
* wind
* H2O
* animals

Sexual

This life cycle is ______


1. 2 haploid (n) fungi


1. hyphae releases pheromones & test compatibility
2. ==Plasmogamy== (fuse cell membranes)


1. n+n cell
2. two nuclei in the same cell
3. results in: ==heterokaryon== (cells contain multiple haploid nuclei (n+n))
3. Time passes
4. Environmental change triggers ==karyogamy==: nuclei fuse


1. 2n cell = zygote
5. Meiosis → 4 (n) cells

Alleles

In a sexual life cycle of a fungus, # of mating types depends on # of _______

Plasmogamy

Fusion of cell membranes → n+n cell

Heterokaryon

Cell that contains multiple haploid nuclei (n+n)

Karyogamy

Nuclear fission → 2n cell = zygote

Asexual

This life cycle is _______


1. spores
2. germination (mitosis)
3. mycelium


1. spore-producing structures

Filamentous fungi (spores via mitosis), single-celled yeast (cell division/budding)

Two main types of asexual fungi

Chytrids, Zygomycetes, Glomeromycetes, Ascomycetes, Basidiomycetes

5 Phyla of Fungi

Chytrids

* basal fungal group
* derived characteristics: flagellated spores (it’s ancestral to other fungal groups, which lack flagella)
* zoospores unique to ________
* terrestrial, freshwater, marine

Zoospores

Flagellated spores unique to chytrids

Zygomycetes

* derived characteristics: zygospores in zygosporangia
* most are soil decomposers
* ex: black bread mold (*rhizopus stolonifer*)

Glomeromycetes

* derived characteristics: ==mycorrhizae== = symbiotic relationship w/ most plants
* mutualism present in >80% of plants
* help uptake water & ions

Ascomycetes

* derived traits:
* spores contained in sacs (ascopores?)
* can be single-celled or filaments
* largest number of known species (\~65k)
* examples (so many!)
* penicillium
* morels and truffles
* baker’s/brewer’s yeast
* component of lichens (will discuss later)

Basidiomycetes

* spores in basidiocarp (gills) (basidiospores?)
* “mushrooms”
* no asexual stage in life cycle
* examples
* bracket fungi
* puff balls
* wheat rust, corn smut
* edible mushrooms

* Decomposers
* Mutualists
* Parasites/Mycosis
* Practical Uses

Ecological Importance of Fungi

Decomposers

* break down organic material (including cellulose & lignin)
* essential - recycle inorganic nutrients
* no decomposers, no life

Mutualists

* Absorb nutrients from host, provide some benefit to them
* Leaf clutter ants and fungi
* Fungus plant examples:
* mycorrhizae
* Mutualism between fungi and plant root
* Endophytes
* inside leave or stems, make toxins
* deter herbivores
* Lichen
* symbiotic association
* fungus and photosynthetic microorganism
* fungal part = ascomycetes
* provides habitat for microbe growth
* protection, retains water & nutrients

Parasites

* fungal infection
* ==mycosis== = fungal infection in an animal
* examples
* thrush: fungal infection in baby’s mouth & mom’s nipples
* ringworm: contagious fungal infection on flush (antifungal treatment), related to athlete’s foot
* Ergots on rye: on plants (common in Europe during wet summers)

Practical Uses

* medicine
* antibiotic production
* research
* eukaryotic genetics


* consumption/food
* blue cheese, wine & beer
* yeast
* ferments sugars into CO2 & alcohol

Summary

I & III

Identify which of the following is/are characteristic of fungi

I. reproduce with spores

II. photosynthetic

III. absorptive heterotrophy

IV. cellulose cell wall