Domain Eukarya

Kingdom Fungi

Anatomy of a fungus• Most fungi grow as

multicellular mycelia made up of long, thin filaments called hyphae.

• Most of a fungi will be invisible to us. Only the reproductive structures above ground will be seen.

Anatomy of a fungus• The hyphae of fungi may or

may not be divided into separate cells by septa

• Septa No septa

Fungi can be multicellular or unicellular

• Multicellular mycelia: . This mycelium is from the rind of a piece of Melbury cheese.

• The yeast pictured here is baker’s yeast, Saccharomyces cerevisiae.

HyphaeReproductivestructure

Mycelium

SeptaCell wall

Pore

Fungi are absorptively heterotrophic

• Fungi can break down almost any type of organic substance– secrete enzymes to digest

food outside– absorb nutrients back in– may be saprobes,

detritivores, parasitic, mutualistic, predatory

• Fungal morphology is associated with their mode of nutrition: the fungal mycelium maximizes surface area in relation to volume.

Fungal decomposition (saprophytic)

Parasitism

• Although many fungi infect humans, relatively little human disease is due to fungi.

• Parasitic fungi cause major damage to crops such as wheat, corn, and barley.

Fungi reproduce by producing spores

• The reproductive structures of fungi produce haploid spores

spore

• A new fungal mycelium begins with the germination of a haploid spore

The Fungal Life Cycle

•‘vegetative’ life form typically haploid

•May reproduce asexually through haploid spores

The Fungal Life Cycle

•Sexual reproduction through

–cytoplasm fusion --> dikaryotic stage (n + n) or heterokaryotic

–nuclear fusion--> diploid stage

–typically rapid meiosis--> haploid spores

Four groups of Fungi

Chytridiomycota

• Mainly aquatic

• Flagellated spores

• Basal group of the

Fungi

Phylum Zygomycota

• Rhizopus (bread mold), fruit rot

• when two different hyphae join together for sexual reproduction, they form a swollen, thick-walled structure (zygosporangia) that links the hyphae together

Figure 31.7 The life cycle of the zygomycete Rhizopus (black bread mold)

Figure 31.7x2 Mature zygosporangium

Bread mold

Bread Molds, Black Bread Mold, Rhizopus stolonifera, not only grow on Bread, but anywhere there are water and nutrients.

Phylum Ascomycota

• Sac Fungi

• Fruiting structure called an ascocarp

• Produce spores in sac-like compartments called asci

MorelTruffle

Figure 31.10 The life cycle of an ascomycete

Asexual spores produced in conidia

Sexual spores produced in ascocarps

Other Ascomycetes

Baker’s yeast: Saccharomyces cerevisiae

Penicillin molds

Chestnut blight

Phylum Basidiomycota

• Club Fungi: Mushrooms, shelf fungi, rusts and smuts, puffballs

• Seldom reproduce asexually.

Club fungi reproduce sexually by forming spores in a structure called a BASIDIUM (BASIDIA) which can be found lining gills inside the BASIDIOCARP (the mushroom cap).

Mushrooms PoisonousEdible

Hallucinogenic

Table 31.1 Review of Fungal Phyla

“Phylum” Glomeromycota?

• Mycorrhizae are fungi that associate with plant roots and receive sugars from them.

• Two types:– Exomycorrhizae– Endomycorrhizae (also called arbuscular)

Rootcells

EMF

•Common in colder northern climates (decomposition is slow)

•The fungus breaks down organic material and delivers nitrogen to the plant.

Ectomycorrhizae grow on the surface of plant roots without penetrating the cells.

AMF

Rootcells

Roothair

•Common in warmer grasslands & forests (decompositionis rapid).

•The fungus delivers phosphorus to the plant.

Arbuscular mycorrhizae penetrate the cells of the plant root.

Number of AMF species Number of AMF species

Sh

oo

t b

iom

ass

Pla

nt

sp

ecie

s d

iver

sity

0 1 2 4 8 14 0 1 2 4 8 140

0.2

0.8

0.4

0.6

130

110

70

90

Effect of AMF species diversity on plants:

Mutualisms:• Increasing the diversity of mycorrhizae in a given

habitat increases plant species richness and productivity.

Mutualisms• Lichens

– Lichens are associations of a fungus with either an alga or cyanobacterium.

• Lichens are the dominant species in tundra habitats and are important in breaking down rock to form soil.

Asexual reproductionoccurs when “mini-lichens”are produced.

Asciproduced byfungus

Fungal layer

Fungal layer

Algal layer

Substrate

Figure 29.11a

Types of Lichens

•crustose, fruticose, foliose

Dutch Elm Disease

• Entered the U.S. in the 1930’s

• Has been moving westward ever since

• Chicago lost 119,000 trees in 3 years

• Entered the U.S. early 20th century

• Before: as many as 1 in 4 trees were chestnuts (e. of Mississippi)

• 100,000s of trees lost (3.5 billion in 40 years?)

• Tree now present as an understory tree produced by sprouting from roots

Chestnut blight

Cell walls of fungi are made of chitin

(Cell walls of plants are made of cellulose)

Chitin also makes up the exoskeleton of arthropods

Fungi used to be classified with plants

Plants• Photosynthetic

• Cell wall made of cellulose

• Develop from embryos

Fungi• Heterotrophic

• Cell wall made of chitin

• Develop from spores

…but there are major differences