2Anatomy of a fungusMost 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.
3Anatomy of a fungusThe hyphae of fungi may or may not be divided into separate cells by septaSepta No septa
4Fungi 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.
5Fungi are absorptively heterotrophic PoreFungi can break down almost any type of organic substancesecrete enzymes to digest food outsideabsorb nutrients back inmay be saprobes, detritivores, parasitic, mutualistic, predatoryCell wallSeptaReproductivestructureHyphaeMyceliumFungal morphology is associated with their mode of nutrition: the fungal mycelium maximizes surface area in relation to volume.
12Chytridiomycota Mainly aquatic Flagellated spores Basal group of the Fungi
13Phylum 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
14Figure 31.7 The life cycle of the zygomycete Rhizopus (black bread mold)
24“Phylum” Glomeromycota? Mycorrhizae are fungi that associate with plant roots and receive sugars from them.Two types:ExomycorrhizaeEndomycorrhizae (also called arbuscular)
25Ectomycorrhizae grow on the surface of plant roots without penetrating the cells. EMFFigure: 29.9aCaption:(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.
26Arbuscular mycorrhizae penetrate the cells of the plant root. AMFRoothairFigure: 29.9bCaption:(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.
27Plant species diversity Mutualisms:Increasing the diversity of mycorrhizae in a given habitat increases plant species richness and productivity.Number of AMF speciesShoot biomassPlant species diversity1248184.108.40.206.61301107090Effect of AMF species diversity on plants:
28MutualismsLichensLichens 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.
29Figure 29.11a Asexual reproduction occurs when “mini-lichens” are produced.Asciproduced byfungusFungal layerAlgal layerFigure: 29.11aCaption:(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 layerSubstrate
31Dutch Elm Disease Entered the U.S. in the 1930’s Has been moving westward ever sinceChicago lost 119,000 trees in 3 years
32Chestnut 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
33Cell walls of fungi are made of chitin Chitin also makes up the exoskeleton of arthropods(Cell walls of plants are made of cellulose)
34Fungi used to be classified with plants …but there are major differencesPlantsPhotosyntheticCell wall made of celluloseDevelop from embryosFungiHeterotrophicCell wall made of chitinDevelop from spores