what is the biggest organism in this oregonian forest?

What is the biggest organism in this Oregonian forest?

Hint, it is pictured

The honey mushroom fungus

Fun-gi vids

• pig decomposition time-lapse• fungus time-lapse• growing mold time-lapse• parasitic fungi time-lapse

http://www.youtube.com/watch?v=R1CD6gNmhr0&safety_mode=true&safe=active

LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITION

Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

© 2011 Pearson Education, Inc.

Lectures byErin Barley

Kathleen Fitzpatrick

Fungi

Chapter 31

Concept 31.1: Fungi are heterotrophs that feed by absorption

• Fungi are heterotrophs and absorb nutrients from outside of their body

• Fungi use enzymes to break down a large variety of complex molecules into smaller organic compounds

• Fungi exhibit diverse lifestyles– Decomposers– rabbit decomposing

– Parasites– previously shown, with new bonus mushroom and slime mold time-lapse

– Mutualists



Animation: Fungal Reproduction and Nutrition Right-click slide / select “Play”

Anatomy basics•Fungi consist of mycelia, networks of branched hyphae adapted for absorption•A mycelium’s structure maximizes its surface area-to-volume ratio•Fungal cell walls contain chitin


Reproductive structure

Hyphae

Spore-producingstructures

Mycelium

60 m

Figure 31.2

TWO FORMS OF HYPHAE

(a) Septate hypha (b) Coenocytic hypha

NucleiCell wall

Pore

Septum Nuclei

Cell wall

1 pinch of soil can contain 1 km of hyphae

How much hyphae did she eat?

Some unique fungi have specialized hyphae called haustoria that allow them to penetrate the tissues of their host

(a) Hyphae adapted for trapping and killing prey

(b) Haustoria

Fungal hypha Plantcellwall

Plant cell

Plant cellplasmamembraneHaustorium

NematodeHyphae 25 m

• Mycorrhizae are mutually beneficial relationships between fungi and plant roots, which most vascular plants have– Ectomycorrhizal fungi form sheaths of hyphae over

a root and also grow into the extracellular spaces of the root cortex

– Arbuscular mycorrhizal fungi extend hyphae through the cell walls of root cells and into tubes formed by invagination of the root cell membrane

• Which is pictured ?• Which is pictured on the previous slide?


Concept 31.2: Fungi produce spores through sexual or asexual life cycles

• Fungi propagate themselves by producing vast numbers of spores, either sexually or asexually, or both


Fungi life cycle paths can be funky

Key

Haploid (n)

Heterokaryotic

Diploid (2n)

Spores


ASEXUALREPRODUCTION

GERMINATION

Mycelium

PLASMOGAMY

Key

Haploid (n)

Heterokaryotic

Diploid (2n)

Spores


ASEXUALREPRODUCTION

SEXUALREPRODUCTION

GERMINATION

Zygote

Heterokaryoticstage

KARYOGAMY

Mycelium


PLASMOGAMY, based on pheromone compatibility

Key

Haploid (n)

Heterokaryotic

Diploid (2n)

Spores


ASEXUALREPRODUCTION

SEXUALREPRODUCTION

GERMINATIONGERMINATION MEIOSIS

Spores

Zygote

Heterokaryoticstage

KARYOGAMY

Mycelium


Asexual Reproduction

• In addition to sexual reproduction, many fungi can reproduce asexually

• Molds produce haploid spores by mitosis and form visible mycelia


Figure 31.7

10 m

Parentcell

Bud

CHECK-IN Q•Yeast are unicellular and reproduce by budding. Then what makes them fungi?

• DNA evidence suggests that – Fungi are most closely related to unicellular

nucleariids – Animals are most closely related to unicellular

choanoflagellates

• Based on this, did fungi and animals split before or after the emergence of multicellularity?


Concept 31.3: The ancestor of fungi was an aquatic, single-celled, flagellated protist

The Move to Land

• If fungi are heterotrophic, how does it make sense that they were among the first land colonizers?


The Move to Land

• If fungi are eukaryotic, how does it make sense that they were among the first land colonizers?


Concept 31.4: Fungi have radiated into a diverse set of lineages

• Molecular analyses have helped clarify evolutionary relationships among fungal groups, although areas of uncertainty remain


Figure 31.11Chytrids (1,000 species)

Zygomycetes (1,000 species)

Glomeromycetes (160 species)

Ascomycetes (65,000 species)

Basidiomycetes (30,000 species)

Hyphae 25 m

25 mFungal hypha

Chytrids

• Chytrids (phylum Chytridiomycota) are found in freshwater and terrestrial habitats

• They can be decomposers, parasites, or mutualists

• Molecular evidence supports the hypothesis that chytrids diverged early in fungal evolution

• Chytrids are unique among fungi in having flagellated spores, called zoospores



Video: Allomyces Zoospore Release


Video: Phlyctochytrium Zoospore Release

Zygomycetes

• The zygomycetes (phylum Zygomycota) exhibit great diversity of life histories

• They include fast-growing molds, parasites, and commensal symbionts

• The life cycle of black bread mold (Rhizopus stolonifer) is fairly typical of the phylum

• Its hyphae are coenocytic • Asexual sporangia produce haploid spores


Figure 31.UN02

Chytrids

Zygomycetes

GlomeromycetesAscomycetes

Basidiomycetes

Figure 31.13

Rhizopusgrowingon bread

Flagellum

Matingtype () Mating

type ()

Gametangia withhaploid nuclei

Youngzygosporangium(heterokaryotic)

PLASMOGAMY

100 m

50 m

ZygosporangiumKARYOGAMY

SEXUALREPRODUCTION

Diploidnuclei

Key

Haploid (n)

Diploid (2n)

Heterokaryotic (n n)

Sporangium

MEIOSIS

Dispersal andgermination


ASEXUAL REPRODUCTION

Mycelium

Sporangia

• The zygomycetes are named for their sexually produced zygosporangia

• Zygosporangia are the site of karyogamy and then meiosis

• Zygosporangia, which are resistant to freezing and drying, can survive unfavorable conditions

• Some zygomycetes, such as Pilobolus, can actually “aim” their sporangia toward conditions associated with good food sources


Figure 31.14

0.5 mm

Pilobolus aiming its sporangia toward light as that is where edible vegitation would be growing (grass). Grass is eaten, spores spread in feces.

Glomeromycetes

• The glomeromycetes (phylum Glomeromycota) were once considered zygomycetes

• They are now classified in a separate clade• Glomeromycetes form arbuscular mycorrhizae


Figure 31.UN03

Chytrids

Zygomycetes


Basidiomycetes

Figure 31.15

2.5 m

Ascomycetes

• Ascomycetes (phylum Ascomycota) live in marine, freshwater, and terrestrial habitats

• Ascomycetes produce sexual spores in saclike asci contained in fruiting bodies called ascocarps

• Ascomycetes are commonly called sac fungi• Ascomycetes vary in size and complexity from

unicellular yeasts to elaborate cup fungi and morels


Figure 31.UN04

Chytrids

Zygomycetes


Basidiomycetes

Figure 31.16

Morchella esculenta,the tasty morel

Tuber melanosporum, a truffle

• Ascomycetes include plant pathogens, decomposers, and symbionts

• Ascomycetes reproduce asexually by enormous numbers of asexual spores called conidia

• Conidia are not formed inside sporangia; they are produced asexually at the tips of specialized hyphae called conidiophores

• Neurospora crassa, a bread mold, is a model organism with a well-studied genome


Conidia;mating type ()

Mating type ()

DispersalGermination

ASEXUALREPRODUCTION Hypha

Conidiophore

Mycelium

Germination

Ascocarp

Dispersal

Asci

Mycelia

Eightascospores

SEXUALREPRODUCTION

Fourhaploidnuclei MEIOSIS

Diploid nucleus(zygote)

KARYOGAMY

Dikaryotichyphae

Ascus(dikaryotic)

PLASMOGAMY

Key

Haploid (n)

Diploid (2n)

Dikaryotic (n n)

Figure 31.17

Basidiomycetes

• Basidomycetes (phylum Basidiomycota) include mushrooms, puffballs, and shelf fungi, mycorrhizae, and plant parasites

• The phylum is defined by a clublike structure called a basidium, a transient diploid stage in the life cycle

• The basidiomycetes are also called club fungi• Many basidiomycetes are decomposers of wood


Figure 31.UN05

Chytrids

Zygomycetes


Basidiomycetes

Figure 31.18 Shelf fungi

Puffballs emittingspores

Maiden veil fungus(Dictyphora)

• The life cycle of a basidiomycete usually includes a long-lived dikaryotic mycelium

• In response to environmental stimuli, the mycelium reproduces sexually by producing elaborate fruiting bodies called basidiocarps

• Mushrooms are examples of basidiocarps• The numerous basidia in a basidiocarp are

sources of sexual spores called basidiospores


Key

Haploid (n)

Diploid (2n)

Dikaryotic (n n) Mating type ()

Mating type ()

Haploidmycelia

SEXUALREPRODUCTION


Basidiospores(n)

Basidium withfour basidiospores

Basidium containingfour haploid nuclei

Basidium

Basidiospore1 m

MEIOSIS

Diploidnuclei

KARYOGAMY

Basidia (n n)

Basidiocarp (n n)

Gills linedwith basidia

DikaryoticmyceliumPLASMOGAMY

Figure 31.19

Figure 31.20

• Basidiomycetes can produce mushrooms quickly• Some species may produce “fairy rings”

Imagine a fungi-free world…

Concept 31.5: Fungi play key roles in nutrient cycling, ecological interactions, and human welfare

• Fungi interact with other organisms as decomposers, mutualists, and pathogens


Fungi as Decomposers/Nutrient recylers

• Fungi are efficient decomposers of organic material including cellulose and lignin

• Fungi are also used in bioremediation projects


Fungi as Mutualists


Fungus-Plant Mutualisms

• Mycorrhizae are enormously important in natural ecosystems and agriculture– Plants harbor harmless symbiotic endophytes, fungi

that live inside leaves or other plant parts– Endophytes make toxins that deter herbivores and

defend against pathogens– Most endophytes are ascomycetes


Figure 31.21

Endophyte not present; pathogen present (EP)

Both endophyte and pathogen present (EP)

EP EPEP EP

30

20

10

0

15

10

5

0

Lea

f m

ort

alit

y (%

)

Lea

f ar

ea d

amag

ed (

%)

RESULTS

Fungi-animal symbiosis

Lichens

• A lichen is a symbiotic association between a photosynthetic microorganism and a fungus– The photosynthetic component is green algae or

cyanobacteria– The fungal component is most often an ascomycete

• The symbioses are so complete that lichens are given scientific names


Figure 31.23

A fruticose (shrublike) lichen

A foliose(leaflike) lichen

Crustose(encrusting) lichens

Lichen anatomy

Ascocarp of fungus

50

m

Fungalhyphae Algal

layer

Soredia

Fungal hyphaeAlgal cell

• Lichens are important pioneers on new rock and soil surfaces

• Lichens may have helped the colonization of land by plants 550–600 million years ago


Fungi as Pathogens

• About 30% of known fungal species are parasites or pathogens, mostly on or in plants

• Each year, 10% to 50% of the world’s fruit harvest is lost due to fungi

• Some fungi that attack food crops are toxic to humans


Figure 31.25

(a) Corn smut on corn

(c) Ergots on rye

(b) Tar spotfunguson mapleleaves

Fungi caused Salem Witch Trials?•Ergotism is characterized by gangrene, nervous spasms, burning sensations, hallucinations, and temporary insanity

– Ergots contain lysergic acid, the raw material for LSD


Global amphibian populations are down due to fungal infection (mycosis)

California

SixtyLakeBasin

Yellow-legged frogskilled by B. dendrobatidisinfection

KeyBoundary of chytrid spread

Lake status in 2009:

Frog population extinct

Treatment lake: frogstreated with fungicidesand released

N

2004

2005

2006

20082007

Practical Uses of Fungi

• Humans eat many fungi and use others to make cheeses, alcoholic beverages, and bread

• Some fungi are used to produce antibiotics for the treatment of bacterial infections

– For example, the ascomycete Penicillium


Fungal production of antibiotic

Zone ofinhibitedgrowth

Staphylococcus Penicillium

Figure 31.UN06

FungalPhylum

Distinguishing Features ofMorphology and Life Cycles

Chytridiomycota(chytrids)

Flagellated spores

Zygomycota(zygote fungi)

Resistant zygosporangiumas sexual stage

Glomeromycota(arbuscularmycorrhizalfungi)

Arbuscular mycorrhizaeformed with plants

Ascomycota(ascomycetes, orsac fungi)

Sexual spores (ascospores)borne internally in sacscalled asci; vast numbersof asexual spores (conidia)produced

Basidiomycota(basidiomycetes,or club fungi)

Elaborate fruiting body(basidiocarp) containingmany basidia thatproduce sexual spores(basidiospores)

Figure 31.UN08

Figure 31.UN09

Figure 31.UN10

what is the biggest organism in this oregonian forest?

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