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.

Fungi are absorptively heterotrophic Pore 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 Cell wall Septa Reproductive structure Hyphae Mycelium 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 A new fungal mycelium begins with the germination of a haploid spore 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 Truffle Morel

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).

Edible Mushrooms Poisonous 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)

Ectomycorrhizae grow on the surface of plant roots without penetrating the cells. EMF Figure: 29.9a Caption: (a) Ectomycorrhizal fungi (EMF) form a dense network around the roots of plants. The combination of root and fungus is called a mycorrhiza. The drawing shows how the interaction works in EMF. Note that their hyphae penetrate the intercellular spaces of the root, but do not enter the cells themselves.  Common in colder northern climates (decomposition is slow) The fungus breaks down organic material and delivers nitrogen to the plant.

Arbuscular mycorrhizae penetrate the cells of the plant root. AMF Root hair Figure: 29.9b Caption: (b) Interactions of arbuscular mycorrhizal fungi (AMF) with roots. The fungal hyphae penetrate the root cell walls and contact the plasma membrane, where they branch into bushy structures called arbuscules. The photograph shows a fossilized arbuscule, from an AMF, inside a plant cell. The fossil is over 390 million years old. Common in warmer grasslands & forests (decomposition is rapid). The fungus delivers phosphorus to the plant.

Plant species diversity Mutualisms: Increasing the diversity of mycorrhizae in a given habitat increases plant species richness and productivity. Number of AMF species Shoot biomass Plant species diversity 1 2 4 8 14 0.2 0.8 0.4 0.6 130 110 70 90 Effect of AMF species diversity on plants:

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.

Figure 29.11a Asexual reproduction occurs when “mini-lichens” are produced. Asci produced by fungus Fungal layer Algal layer Figure: 29.11a Caption: (a) In a lichen, green algae or cyanobacteria are enmeshed in a dense network of fungal hyphae. In this example, the fungal participant is an ascomycete. Fungal layer Substrate

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

Chestnut blight 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

Cell walls of fungi are made of chitin Chitin also makes up the exoskeleton of arthropods (Cell walls of plants are made of cellulose)

Fungi used to be classified with plants …but there are major differences Plants Photosynthetic Cell wall made of cellulose Develop from embryos Fungi Heterotrophic Cell wall made of chitin Develop from spores