Today: Review of the “Fungus- like” Protists The REAL Fungi Reminder: Fieldtrip Monday! Wear...

Today:Today:•Review of the “Fungus-like” Protists

•The REAL Fungi

Reminder:Fieldtrip Monday! Wear close-toed shoes. Dress for the weather. Meet at the Administration Building at 1 pm.

The Absorptive Protists: A Closer The Absorptive Protists: A Closer LookLook

What do we know about these??What do we know about these??

Could you draw a lifecycle??

Could you draw a lifecycle??

The Plasmodial Slime Mold Life CycleThe Plasmodial Slime Mold Life Cycle

The Dictyostelida- Cellular The Dictyostelida- Cellular Slime MoldsSlime Molds

Feeding stage consists of Feeding stage consists of solitary cells functioning solitary cells functioning individuallyindividually

When food is low, cells follow When food is low, cells follow chemical trails to form an chemical trails to form an aggregate (pseudoplasmodium)aggregate (pseudoplasmodium)

Cells in the aggregate maintain Cells in the aggregate maintain their membranestheir membranes

Haploid organisms!Haploid organisms! Most have no flagellated stagesMost have no flagellated stages

The Dictyostelida- Cellular Slime MoldsThe Dictyostelida- Cellular Slime Molds

http://dictybase.org/Multimedia/development/development.html

The Oomycotes (Water Molds The Oomycotes (Water Molds and Their Relatives)and Their Relatives)

Oomycota: Water Molds and Oomycota: Water Molds and Their RelativesTheir Relatives

Includes water molds, white rusts, and Includes water molds, white rusts, and downy mildewsdowny mildews

All are heterotrophic stramenopiles (“straw All are heterotrophic stramenopiles (“straw hair”)hair”)

May be unicellular or consist of multi-May be unicellular or consist of multi-nucleated hyphae (convergent evolution!!)nucleated hyphae (convergent evolution!!)

Have cell walls made of Have cell walls made of cellulosecellulose Most are Most are diploid dominant diploid dominant (unlike true (unlike true

fungi!)fungi!) Have Have biflagellated cells biflagellated cells during their life during their life

cyclecycle

White RustsWhite Rusts

Generally parasites of Generally parasites of terrestrial plantsterrestrial plants

Flagellated zoospores Flagellated zoospores infect and feed on infect and feed on

plant tissuesplant tissues

white pine blister rust is the pale to orange

colored blisters formed on white pine stem

after infection

chrysanthemum with CWR

Arabidopsis thaliana - Peronospora parasitica. P. parasitica is a downy

mildew pathogen belonging to the

oomycetes

Downy Mildews

Also typically parasites of terrestrial plants

Downey mildew on soybeans

Other Famous OomycetesOther Famous Oomycetes

Potato blight (caused Potato blight (caused Irish Famine- late Irish Famine- late 1840’s)1840’s)

The Water MoldsThe Water Molds Important decomposers Important decomposers

and parasites in aquatic and parasites in aquatic systemssystems

secondary Saprolegnia infection

Next: Thinking Next: Thinking About About Real Real

FungiFungi

General CharacteristicsGeneral Characteristics

General CharacteristicsGeneral Characteristics

Mostly multicellular eukaryotesMostly multicellular eukaryotes More closely related to animals than More closely related to animals than

plants!plants! Distinguished by their:Distinguished by their:

Nutritional ModeNutritional Mode

Structural OrganizationStructural Organization

Growth Growth

ReproductionReproduction

Nutritional Mode- FungiNutritional Mode- Fungi HeterotrophsHeterotrophs Acquire nutrients by Acquire nutrients by

absorptionabsorption External digestion External digestion

((exoenzymesexoenzymes)) Makes them important Makes them important

decomposers!decomposers! Parasitic fungi digest Parasitic fungi digest

and absorb tissues of and absorb tissues of host!host!

Fairy Fairy RingsRings

WHY??WHY??

Could you draw a typical fungal body?? Try to

include the following key terms:

hyphae, septa, mycellium

Could you draw a typical fungal body?? Try to

include the following key terms:

hyphae, septa, mycellium

Structural Organization- Structural Organization- FungiFungi

Vegetative bodies usually diffusely Vegetative bodies usually diffusely organized within and around the food organized within and around the food sourcesource

Except yeasts, fungi constructed of Except yeasts, fungi constructed of filamentous filamentous hyphaehyphae

Hyphae form an interwoven mat, a Hyphae form an interwoven mat, a mycelliummycellium

Largest mycellium discovered is 3.4 Largest mycellium discovered is 3.4 miles in diameter!!miles in diameter!!

The Fungi: Structural OrganizationThe Fungi: Structural Organization

Most hyphae are divided into cells by cross-Most hyphae are divided into cells by cross-walls called walls called septasepta (septa have large pores!) (septa have large pores!)

Some fungi are Some fungi are aseptateaseptate- no divisions within - no divisions within the hyphae. These are the the hyphae. These are the Coenocytic Coenocytic FungiFungi

Parasitic fungi have modified hyphae, Parasitic fungi have modified hyphae, haustoriahaustoria, specialized to penetrate the , specialized to penetrate the tissues of the hosttissues of the host

Most fungal cell walls are composed of Most fungal cell walls are composed of chitinchitin


Fungal GrowthFungal Growth Growth is Growth is

extremely rapid! extremely rapid! (can add 1 (can add 1 kilometer per day kilometer per day of hyphae!!)of hyphae!!)

Possible because of Possible because of efficient transfer of efficient transfer of materials by materials by cytoplasmic cytoplasmic streaming to the streaming to the tipstips

Fungal Dispersal and ReproductionFungal Dispersal and Reproduction Fungi reproduce by releasing sporesFungi reproduce by releasing spores Spores may be produced either sexually or Spores may be produced either sexually or

asexuallyasexually A single fungus may produce trillions of A single fungus may produce trillions of

sporesspores

Fungal Life CyclesFungal Life Cycles

Most fungal hyphae and spores are Most fungal hyphae and spores are haploidhaploid

Some mycelia may form through the Some mycelia may form through the fusion of two genetically distinct hyphae. fusion of two genetically distinct hyphae. This mycelium is then a This mycelium is then a heterokaryonheterokaryon..

The distinct nuclei may remain isolated, or The distinct nuclei may remain isolated, or may mingle and even exchange may mingle and even exchange chromosomes and genes via a cross-over chromosomes and genes via a cross-over like process.like process.

Sexual Reproduction in Sexual Reproduction in FungiFungi

In sexually reproducing fungi, the union In sexually reproducing fungi, the union occurs in two stages:occurs in two stages:

1. 1. Plasmogamy-Plasmogamy- fusion of the fusion of the parents’ parents’ cytoplasmcytoplasm

2. 2. Karyogamy-Karyogamy- fusion of haploid fusion of haploid nuclei of nuclei of the two parentsthe two parents

During the time lag (minutes to centuries!) During the time lag (minutes to centuries!) the mycelium is a the mycelium is a heterokaryonheterokaryon

Occasionally the haploid nuclei pair off, two Occasionally the haploid nuclei pair off, two to a cell. This mycelium is to a cell. This mycelium is dikaryotic.dikaryotic.

Sexual Reproduction in Sexual Reproduction in FungiFungi

You Try!

Fungal Fungal EvolutionEvolution

Animals and Animals and fungi from a fungi from a

common common aquatic, aquatic,

flagellated, flagellated, protistan protistan ancestor?ancestor?

EvolutioEvolution of the n of the FungiFungi

The ChytridiomycotaThe Chytridiomycota

Mainly aquaticMainly aquatic May be saprobes, May be saprobes,

parasitesparasites Form flagellated Form flagellated

spores (zoospores) spores (zoospores) Protists??Protists??

Most have Most have coenocytic hyphae, coenocytic hyphae, some unicellularsome unicellular

Chytrids and Fungal Chytrids and Fungal EvolutionEvolution

Chytrids are found Chytrids are found associated with associated with plants very early in plants very early in the fossil record the fossil record ((408-360 million years ago)

Molecular evidence Molecular evidence also suggests these also suggests these are the most are the most primitive fungi primitive fungi

The Zygomycota- the Zygote The Zygomycota- the Zygote FungiFungi

Mostly terrestrial in soil Mostly terrestrial in soil or on decaying materialor on decaying material

Distinguished by a Distinguished by a resistant resistant zygosporangiumzygosporangium

Hyphae are coenocytic Hyphae are coenocytic with septa only where with septa only where reproductive cells are reproductive cells are formedformed

You Try: Modify your generic fungal lifecycle to represent a zygomycete.

Zygomycete Life Cycle

Famous Famous ZygomycotaZygomycota

The black bread mold, The black bread mold, RhizopusRhizopus

The dung fungus, The dung fungus, PilobolusPilobolus

The Glomero-The Glomero-mycetesmycetes

Small but Small but ecologically distinct ecologically distinct group!group!

Form Form arbuscular arbuscular mychorrhizaemychorrhizae

Photo: Ryan Geil

EvolutioEvolution of the n of the FungiFungi

The Ascomycota (Sac Fungi)The Ascomycota (Sac Fungi)

30,000+ species from 30,000+ species from marine, freshwater, and marine, freshwater, and terrestrial habitatsterrestrial habitats

Unicellular yeasts to Unicellular yeasts to large elaborate morels!large elaborate morels!

Many live with algae as Many live with algae as lichens, may also form lichens, may also form mycorrhizae with plants, mycorrhizae with plants, or between cells in or between cells in leaves!leaves!

You Try: Modify your generic fungal lifecycle to represent an Ascomycete.

Ascomycetes

Other AscomycetesOther Ascomycetes

Infamous Infamous AscomycetesAscomycetes

……

An American Chestnut Tree with Chestnut Blight

The Basidiomycota- Club FungiThe Basidiomycota- Club Fungi

~30,000 fungi ~30,000 fungi including including mushrooms, shelf mushrooms, shelf fungi, puffballs, fungi, puffballs, and rusts & smutsand rusts & smuts

Important Important decomposers decomposers (lignin!), also form (lignin!), also form mycorrhizamycorrhiza

You Try: Modify your generic fungal lifecycle to

represent a Basidiomycete.

Other BasidiomycetesOther Basidiomycetes

Wood RotWood Rot

Brown Wood Rot: Brown Wood Rot: Fungi eats cellulose Fungi eats cellulose and leaves behind and leaves behind brown ligninbrown lignin

White Wood Rot: Fungi White Wood Rot: Fungi eats brown lignin and eats brown lignin and leaves behind white leaves behind white cellulosecellulose

Very important to Very important to nutrient cycling!!nutrient cycling!!

Images: Tom Volks, University of Wisconsin

EvolutionarilyEvolutionarily, the Fungi , the Fungi are Divided are Divided into Phyla into Phyla based on based on

Reproductive Reproductive StrategyStrategy

Ecological Adaptations in the Ecological Adaptations in the FungiFungi

1. Molds- 1. Molds- Rapidly growing, Rapidly growing,

asexually asexually reproducing fungusreproducing fungus

Grow as saprobes or Grow as saprobes or parasites on a parasites on a variety of substratesvariety of substrates

Example: Example: PenicilliumPenicillium (an (an ascomycete)ascomycete)

Molds that have no Molds that have no known sexual stage are known sexual stage are called imperfect fungi called imperfect fungi

(deuteromycetes)(deuteromycetes)

2. Yeasts-2. Yeasts- Unicellular fungi in Unicellular fungi in

moist of liquid habitatsmoist of liquid habitats Reproduce asexually by Reproduce asexually by

simple division or simple division or buddingbudding

Includes members of Includes members of the Ascomycota, the Ascomycota, Basidiomycota and Basidiomycota and Imperfect Fungi.Imperfect Fungi.


3. Lichens-3. Lichens-

Symbiotic association of millions of algae or Symbiotic association of millions of algae or cyanobacteria within a mesh of fungal cyanobacteria within a mesh of fungal hyphae (most commonly ascomycetes)hyphae (most commonly ascomycetes)


3. Lichens-3. Lichens-Lichens absorb most of Lichens absorb most of

their minerals from dust their minerals from dust or rain, making them or rain, making them good colonizers, but good colonizers, but sensitive to pollutants.sensitive to pollutants.

Lichens survive in very arid Lichens survive in very arid conditions, but conditions, but photosynthesize only photosynthesize only when water levels are when water levels are sufficient, resulting in sufficient, resulting in extremely slow growth.extremely slow growth.


4. Mycorrhizae-4. Mycorrhizae- Mutualistic associations of Mutualistic associations of

plant roots and fungiplant roots and fungi Increase the absorptive Increase the absorptive

surface of the plant rootssurface of the plant roots Fungus provides minerals for Fungus provides minerals for

organic nutrients organic nutrients synthesized by the plantsynthesized by the plant

Found in almost all vascular Found in almost all vascular plants!plants!


4. Mycorrhizae-4. Mycorrhizae-Can be endo or ecto-Can be endo or ecto-

mycorrhizaemycorrhizae

EndoEndomycorrhizae- penetrates mycorrhizae- penetrates the cortical cells (but not the the cortical cells (but not the

cell membrane); usually a cell membrane); usually a zygomycete (Arbuscular zygomycete (Arbuscular

Mycorrhizal Fungi)Mycorrhizal Fungi)

EctoEctomycorrhizae- forms a mycorrhizae- forms a sheath around the root; sheath around the root; usually a basidiomyceteusually a basidiomycete


EctomycorrhizaeEctomycorrhizaeEctomycorrhizae occur in almost all tree species in

temperate and boreal forests. Short growing seasons in these areas limit decomposition and create nitrogen

stress. The fungi release peptidases (exoenzymes) that break down proteins, releasing N-containing compounds.

EndomycorrhizaeEndomycorrhizae

Endomycorrhizae are found in ~80% of all plants, especially in warm/tropical grasslands and forests. They help supply phosphorus to

the plants.

Most vascular plants are associated with mycorrhizae.Most vascular plants are associated with mycorrhizae.Photo: Barley grown with (right) and without (left) mycorrhizae.Photo: Barley grown with (right) and without (left) mycorrhizae.

An Unusual An Unusual Niche: Indian Niche: Indian

PipePipe

This This plantplant does not does not photosynthesize! photosynthesize!

Other Interesting FungiOther Interesting Fungi

Some produce Some produce antibiotics, like antibiotics, like

penicillin!penicillin!

Discovered, Discovered, accidentally, in 1928 accidentally, in 1928 (from (from Penicillium Penicillium notatum)notatum)

Tested in humans 1941Tested in humans 1941 Nobel prize, 1945- Nobel prize, 1945-

(Fleming, Florey, and (Fleming, Florey, and Chain)Chain)

Photo: Alexander Fleming's photo of the dish with bacteria and Penicillin mold


Food ProductionFood Production

SEM; Saccharomyces cerevisiae


AflatoxinsAflatoxins

First identified from First identified from Aspergillus flavusAspergillus flavus when when turkeys fed moldy turkeys fed moldy peanut meal fell illpeanut meal fell ill

Many other mycotoxins Many other mycotoxins now identified!now identified!

Aflatoxins appear to cause stunted Aflatoxins appear to cause stunted growth, liver problems and immune growth, liver problems and immune system suppresion, especially in system suppresion, especially in childrenchildrenPhoto: AgriForumPhoto: AgriForum


Fungal PathogensFungal Pathogens

Above: Tinea dorporis (ring worm) - Acute - Forearm

At Right: Top= normal esophagus, Bottom = Esophageal candidiasis

Fungal hyphae growing through a Fungal hyphae growing through a hair from a cat with ringworm.hair from a cat with ringworm.


Poisonous Poisonous Mushrooms Mushrooms (Toadstools)(Toadstools)

Especially Especially AmanitaAmanita sp. (Death’s cap)sp. (Death’s cap)

Toxin produced Toxin produced inhibits mRNA inhibits mRNA

synthesis!synthesis!

Death Cap (Amanita phalloides) Photo: perspective.com


Hallucinogenic Hallucinogenic mushroomsmushrooms

Produce two alkaloids, Produce two alkaloids, psylocibin and psylocin psylocibin and psylocin (structurally similar to (structurally similar to serotonin and LSD)serotonin and LSD)

Resemble toxic Resemble toxic mushrooms!!mushrooms!! Fly Agaric (Amanita muscaria)

Photo: perspective.com

Some Quick Lab Review…Some Quick Lab Review…

What is this? Can you identify key structures?

Today: Review of the “Fungus- like” Protists The REAL Fungi Reminder: Fieldtrip Monday! Wear...

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Transcript of Today: Review of the “Fungus- like” Protists The REAL Fungi Reminder: Fieldtrip Monday! Wear...