biology sylvia s. mader michael windelspecht chapter 22 fungi evolution and diversity lecture...

BiologySylvia S. Mader

Michael Windelspecht

Chapter 22 Fungi Evolution and Diversity

Lecture Outline

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into

PowerPoint without notes.

1

Outline

• 22.1 Evolution and Characteristics of Fungi• 22.2 Diversity of Fungi• 22.3 Symbiotic Relationships of Fungi

2

22.1 Evolution and Characteristics of Fungi

• The fungi contains over 80,000 species

• Mostly multicellular eukaryotes that share a common mode of nutrition– Heterotrophic

– Saprotrophs - Cells release digestive enzymes and then absorb resultant nutrient molecules

3

Evolution and Characteristics of Fungi

• Protists evolved some 1,500 BYA – Plants, animals, and fungi trace their ancestry

to protists– Molecular data tells us that animals and fungi

shared a common ancestor after plants evolved.

• Animals and fungi are more closely related to each other than either is to plants.

• A flagellated unicellular protist was most likely the common ancestor of fungi and animals

4


• Fungal anatomy doesn’t lend itself to becoming fossilized – Probably evolved a lot earlier than the earliest

known fungal fossil dated 450 MYA. – Mycorrhizae are evident in plant fossils

5

Evolutionary Relationships Among the Fungi

6A

lve

ola

tes

Do

man

Eu

kary

a

Rh

izar

ia

commonancestor ofeukaryotes

common ancestor Red algae

Chlorophytes

Land plants

Charophytes

Apicomplexans

Dinoflagellates

Ciliates

Brown algae

Golden brown algae

Diatoms

Water molds

Diplomonads

Parabasalids

Euglenoids

Kinetoplastids

Cellular slime molds

Plasmodial slime molds

Amoeboids

Animals

Choanoflagellates

Fungi

Radiolarians

Foraminiferans

Nucleariids

Arc

hae

pla

stid

sA

mo

ebo

zoa

ns

Ch

rom

alv

eola

tes

Exc

avat

es

Op

isth

oko

nts

Str

am

eno

ph

iles



7

commonancestor

common ancestor Basidiomycota(club fungi)

Ascomycota(sac fungi)

Glomeromycota(AM fungi)**

Zygomycota(zoospore fungi)

Chytridiomycota(zoospore fungi)

**AM fungi were once considered part of Zygomycota,but molecular data suggest they are a different phylum.




Alv

eo

late

s

Do

man

Eu

kary

a

Rh

izar

ia

commonancestor ofeukaryotes

common ancestor Red algae

Chlorophytes

Land plants

Charophytes

Apicomplexans

Dinoflagellates

Ciliates

Brown algae

Golden brown algae

Diatoms

Water molds

Diplomonads

Parabasalids

Euglenoids

Kinetoplastids

Cellular slime molds

Plasmodial slime molds

Amoeboids

Animals

Choanoflagellates

Fungi

Radiolarians

Foraminiferans

Nucleariids

commonancestor

common ancestor Basidiomycota(club fungi)

Ascomycota(sac fungi)

Glomeromycota(AM fungi)**

Zygomycota(zoospore fungi)

Chytridiomycota(zoospore fungi)

**AM fungi were once considered part of Zygomycota,but molecular data suggest they are a different phylum.

Arc

hae

pla

stid

sA

mo

ebo

zoa

ns

Ch

rom

alv

eola

tes

Exc

avat

es

Op

isth

oko

nts

Str

am

eno

ph

iles

8


• Structure of Fungi– Body (thallus) of most fungi is multicellular

mycelium (yeasts are unicellular)• Consists of a vast network of thread-like hyphae

– Septate fungi have hyphae with cross walls– Nonseptate fungi are multinucleated– Hyphae grow at their tips

• Give the mycelium a large surface area per unit volume

– Cell walls of chitin, like insect exoskeletons– Excess food is stored as glycogen as in animals

9

Mycelia and Hyphae of Fungi

10

a. Fungal mycelia on a corn tortilla

b. Specialized fungal hyphae that bear spores

SEM 300

hypha

spore

Cell wall

nuclei

septum

Septate hyphac. Nonseptate hypha


a: © Gary R. Robinson/Visuals Unlimited; b: © Dennis Kunkel/Visuals Unlimited


• Reproduction of Fungi

– Both sexual and asexual reproduction

– Sexual reproduction involves three stages:

• Haploid Hyphae

• Dikaryotic Stage

• Diploid Zygote

11


• During sexual reproduction, hyphae from two different mating types fuse– Hyphae that contain paired haploid nuclei are said to be

dikaryotic– Nuclear fusion produces a diploid nucleus, which produces

haploid spores by meiosis– Spores germinate directly into haploid hyphae without

embryological development

• Terrestrial fungi usually produce non-motile, windblown spores

• Asexual reproduction usually involves the production of windblown spores

• Unicellular yeasts reproduce asexually by budding

12

22.2 Diversity of Fungi

• R. H. Whittaker (1969) was the first to say– Fungi are separate group from protists, plants,

and animals– His reasoning was that fungi are the only type of

multicellular organism to be saprotrophic. • Some experts place fungi in the supergroup

Opisthokonta• fungal groups: chytrids, zygospore fungi, AM

fungi, sac fungi, and club fungi – Differentiated according to their life cycle and the

type of structure they use to produce spores.

13

Diversity of Fungi

• Chytrids (Chytridiomycota)– Include about 790 species of the simplest fungi. – Some are single cells; others form branched

nonseptate hyphae. – They are unique among fungi

• The only fungi to still have flagellated cells. – Characteristic of aquatic lifestyle, – Some also live in moist soil.

– They produce flagellated gametes and spores. – Most reproduce asexually through the production of

zoospores within a single cell. • The zoospores grow into new chytrids

14

Chytrids Parasitizing a Protist

15

hyphae

chytrid

20 m

algal cellwall


© Dr. Hilda Canter-Lund

Diversity of Fungi

• Zygomycota

– Zygospore fungi

• Mainly saprotrophs decomposing animal and plant remains

• Black bread mold - Rhizopus stolonifer

16

Diversity of Fungi

• Rhizopus stononifer life cycle: – Hyphae of opposite mating types grow toward each other– Hyphae swell at tips; cross walls develop behind each end;

form gametangia– Gametangia merge resulting in a large multi-nucleate cell

• Nuclei of the two mating types pair and then fuse• A thick wall develops around the zygospore

– The zygospore becomes dormant for period– Sporangiophore(s) then sporangia develop, and spores are

released– Spores are dispersed by air currents; germinate into new

haploid mycelia

17

rhizoid

Black Bread Mold, Rhizopus stolonifer

18

NUCLEAR FUSION

3. Gametangia merge andnuclei pair, then fuse.

CYTOPLASMIC F

USION

2. Gametangia form at the end of each hypha. 5. Sporangiophores

develop, and spores are released from sporangium.

1. Hyphae of opposite mating types touch.

4. A thick wall develops around the cell.

Sexualreproduction

Asexualreproduction

+ mating type

– mating type

5 µm

sporangiophore

sporangium

Zygote

diploid (2n)

haploid (n)sporangium

rhizoid

spores (n)

spores (n)

germination of spores

zygospore germination

+ mating type– mating type

mycelium

MEIOSIS

50 µm

gametangia

thick-walledzygospore

Bottom left: © James W. Richardson/Visuals Unlimited; Top right: © David M. Phillips/Visuals Unlimited


Diversity of Fungi

• Glomeromycota (AM fungi)– The arbuscular mycorrhizal (AM) fungi are a

relatively small group of about 160 species• Arbuscules are branching invaginations that the

fungus makes when it invades plant roots • Mycorrhizae are a mutualistic association of plants

and fungi

– They were classified as zygospore fungi for many years

• Now classified as a separate group based on molecular data.

19

Diversity of Fungi

• Sac Fungi– Phylum Ascomycota - about 50,000 species of sac fungi– Most are saprotrophs that digest resistant materials containing

cellulose, lignin, or collagen– Most are composed of septate hyphae– Neurospora was the experimental organism for the one-gene-

one-enzyme studies– Morels and truffles, famous gourmet delicacies revered

throughout the world– Sac fungi cause many plant diseases: powdery mildews; leaf

curl fungi; ergot of rye; chestnut blight and Dutch elm disease– Aspergillus and Candida cause serious human infections– Talaromyces (formerly Penicillium) is the source of penicillin

20

Diversity of Fungi

• Life cycle of Sac fungi– Asexual reproduction is the norm

• Yeast usually reproduce by budding– A small bulge forms on side of cell – Receives a nucleus and gets pinched off and becomes full

size– The other ascomycetes produce spores called conidia or

conidiospores– Vary in size and shape and may be multicellular– Conidia usually develop at the tips of aerial hyphae called

conidiophores • Conidiophores differ in appearance and are used for

identification of fungi• Spores are windblown• Conidia of Cladosporium cause allergies - concentrations of

more than 35,000 conidia/m3 over Leiden (Germany)

21

Asexual Reproduction in Sac Fungi

22

b.a.

conidiabuddingyeast cell


(Both): © David M. Phillips/Visuals Unlimited

Diversity of Fungi

• Sexual reproduction in Sac fungi– Ascus refers to the fingerlike sac that

develops during sexual reproduction– Ascus may be surrounded and protected by

sterile hyphae within a fruiting body called an ascocarp

• In cup fungi, ascocarps are cup-shaped• In morels they are stalked and crowned by a pitted

bell-shaped ascocarp– Haploid hyphae fuse to make a diploid

nucleus– Meiosis followed by mitosis produces 8

ascospores23

Sexual Reproduction in Sac Fungi

24

meiosis

c. Peach leaf curl, Taphrina

ascospores

ascus

fungal hypha

a. Ascocarp of the cup fungus, Sarcoscypha b. Ascocarp of the morel, Morchella

ascospores

200 m

male organ

ridge of pit

pit asci

ascospores

female organ

dikaryotichyphae

nuclearfusionzygote

(2n)matureascus

+ mating type (n)spore

- mating type (n)spore

ridgeof pit

hollowcenter

uppersurfaceof leaf

asexuallyproduced

spore


a(Top): © Walter H. Hodge/Peter Arnold, Inc.; b(Top left): © Corbis Royalty-Free; b(Top right): © James Richardson/Visuals Unlimited; c(Top): © Kingsley Stern

Diversity of Fungi

• Yeasts

– Yeasts can be both beneficial and harmful to humans.

• Saccharomyces cerevisiae are used to make beer and wine

• used in genetic engineering experiments

• Candida albicans is a yeast that causes fungal infections.

– Oral thrush is a Candida infection of the mouth, common in newborns and AIDS patients.

25

Diversity of Fungi

• Molds– Can be helpful to humans.

• Aspergillus is a group of green molds used to produce soy sauce by fermentation of soybeans.

• Aspergillus is used to produce citric and gallic acids

26

Diversity of Fungi

• Molds– Can be harmful to humans

• Aspergillus flavus secretes a toxin that acts as a carcinogen

• Stachybotrys chartarum produces a toxin leading to dermatitis, flu-like symptoms, fatigue, and immune system complications.

• Trichophyton causes athletes foot (a type of tineas)

• Histoplasma capsulatum leads to the “fungal flu” and causes systemic illness

27

Black Mold

28

conidiophore


© SciMAT/Photo Researchers, Inc.

SEM 1,8003

Tineas

29

b.

a.


a: © Dr. P. Marazzi/SPL/Photo Researchers, Inc.; b: © John Hadfield/SPL/Photo Researchers, Inc.

Deadly Fungi

• It is unwise for amateurs to collect mushrooms in the wild– Certain mushroom species are poisonous.

• The red and yellow Amanitas are especially dangerous.

• The death angel mushroom (Amanita phalloides), causes 90% of the fatalities attributed to mushroom poisoning.

– Not serious problems: Abdominal pain, vomiting, delirium, and hallucinations

– Serious problem: the poison inhibits RNA polymerase, leading to liver and kidney damage

30

Diversity of Fungi

• Club fungi– Phylum Basidomycota – 22,000 species– Familiar toadstools, mushrooms, bracket

fungi, puffballs, stinkhorns– Some are poisonous– Also plant diseases such as the smuts and

rusts– Mycelium composed of septate hyphae

33

Diversity of Fungi

• Club fungi

– Usually reproduce sexually

– Haploid hyphae fuse, forming a dikaryotic (n + n) mycelium

– Dikaryotic mycelium forms fruiting bodies called basidiocarps

• Contain club-shaped structures called a basidium

• Nuclear fusion followed by meiosis produces basidiospores

34

Club Fungi

6. Basidiospores are released.

basidiospore

nuclei

basidium

portion of gill

cap

gills

stalk

annulus

development of basidiocarp

zygote

basidiospores

5 m

diploid (2n)

haploid (n)

NUCLEAR FUSION

dikaryotic (n+n)

MEIOSIS

dikaryotic mycelium

Mature mushroom

basidium

2. Mycelium produces mushrooms (basidiocarps).

button stageof mushroom

1. Cytoplasmic fusion, resulting in dikaryotic mycelium.

CYTOPLASMIC FUSION

dikaryoticmycelium

haploidhyphae

7. Germination of spores results in haploid hyphae.

splittingof veil

3. Basidia form on gills of mushroom.

4. Nuclear fusion results in diploid nucleus.

5. Meiosis occurs and basidiospores are produced.

+

–


© Biophoto Associates/Photo Researchers, Inc.35

Club Fungi

36

a. Fairy ring

b. Shelf fungus

c. Pore mushroom, Boletus d. Puffball, Calvatiga gigantea

a: © Glenn Oliver/Visuals Unlimited; b: © imagebroker/Alamy RF; c: © M. Eichelberger/Visuals Unlimited; d: © L. West/Photo Researchers, Inc.


Diversity of Fungi

• Smuts and rusts are club fungi that parasitize cereal crops– Have great economic importance because of annual crop

losses• Do not form basidiocarps• Spores are small and numerous

• Life cycle of rusts often requires two different plant host species – One way to control rusts is to eradicate the alternate host– Wheat rust

• Controlled by breeding new resistant strains of wheat• Requires continuous development, because rust can mutate

37

Smuts & Rusts

38

a. Corn smut, Ustilago

b. Wheat rust, Puccinia

fungus

leaf


a: © Steven P. Lynch; b: © Arthur M. Siegelman/Visuals Unlimited

22.3 Symbiotic Relationships of Fungi

• Lichens– Symbiotic association between a fungus and a

cyanobacterium or green alga• Specialized fungal hyphae penetrate the

photosynthetic symbiont• Nutrients are transferred directly to the fungus

– Possibly mutualistic, but the fungal symbiont is probably a parasite of photosynthetic symbiont

• The photosynthetic symbiont is independent• The fungal symbiont usually can’t grow alone

39

Symbiotic Relationships of Fungi

• Lichens– Three morphological types

• Compact crustose – often located on bare rocks or tree park

• Fruticose – shrublike• Foliose - leaflike

– Can live in areas of extreme conditions– Contribute to soil formation– Sensitive indicators of air pollution

40

Lichen Morphology

411mm

a. Crustose lichen, Xanthoria b. Fruticose lichen, Lobaria c. Foliose lichen, Xanthoparmelia

reproductive unit

fungal hyphae

sac fungireproductivecups

fungal hyphae

algal cell


a: © Digital Vision/Getty Images; b: © Steven P. Lynch c: © Kerry T. Givens

Symbiotic Relationships of Fungi

• Mycorrhizae

– Mutualistic relationships between soil fungi and the roots of most plants

• Give plant greater absorptive surface

• Help plants acquire mineral nutrients in poor soil

– Fungal symbiont is usually a glomerulomycete or a sac fungus

• Hyphae may enter cortex of roots, but not the cytoplasm

– Ectomycorrhizae form a mantle that is exterior to the root, and they grow between cell walls

– Endomycorrhizae penetrate only the cell walls

– The earliest fossil plants have mycorrhizae associated with them

42

biology sylvia s. mader michael windelspecht chapter 22 fungi evolution and diversity lecture...

Documents