Introduction of Fungi

They are classified as eukaryotes,

Fungi can be divided into two basic morphological forms, yeasts and hyphae

Yeasts are unicellular fungi which reproduce asexually by blastoconidia formation (budding) or fission

Hyphae are multi-cellular fungi which reproduce asexually and/or sexually

Most fungi occur in the hyphae form as branching, threadlike tubular filaments. - lack cross walls (coenocytic) - have cross walls (septate) -  clamp connections at the septa which connect the the hyphae elements.

Coenocytic hyphae

Septated Hyphae

COMMON CHARACTERISTICS OF FUNGI 1. Heterotrophy - 'other food'. There are three major categories of heterotrophs, which include the saprophytes, symbionts, and parasites. Saprophytes (feed on dead tissues or organic waste); symbionts (mutually beneficial relationship between a fungus and another organism); parasites (feeding on living tissue of a host).  Parasites that cause disease are called pathogens. Some parasites are obligate parasites (require a living host to survive), while others are facultative or nonobligate  parasites (do not require a living host in order to survive).

2. Body form unicellular filamentous (tube-like strands called hypha (singular) or hyphae (plural). mycelium = aggregate of hyphae sclerotium = hardened mass of mycelium that generally serves as an overwintering stage. multicellular, such as mycelial cords, rhizomorphs, and fruit bodies (mushrooms)

3. Fungus is often hidden from view. It grows through its food source (substratum), excretes extracellular digestive enzymes, and absorbs dissolved food. 4. Indeterminate growth. 5. Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin.      Purpose of Spores                (a) Allows the fungus to move to new food

source.                (b) Resistant stage - allows fungus to survive

periods of adversity.                (c) Means of introducing new genetic

combinations into a population. 6. Vegetative phase of fungus is generally sedentary. 7. Cell wall present, composed of cellulose and/or chitin.

8. Food storage - generally in the form of lipids and glycogen. 9. Eukaryotes - true nucleus and other organelles present. 10. All fungi require water and oxygen (no obligate anaerobes). 11. Fungi grow in almost every habitat imaginable, as long as there is some type of organic matter present and the environment is not too extreme. 12. Diverse group, number of described species is about 69,000 (estimated 1.5 million species total).

Phylums of FungiPhylums of Fungi►Phylum Zygomycota Phylum Zygomycota

- - common mold found on land

►Reproduce by zygosporesEx: Rhizopus - common

bread moldContain root-like

structures (rhizoids) to anchor in bread. Stolons on surface of bread.

A.ASEXUAL REPRODUCTION:

Sporangiospores (aplanospores) or modified sporangia (sac-like merosporangia) functioning as conidia.

B. SEXUAL REPRODUCTION:

Two morphologically similar gametangia fuse to produce a warty, thick zygospore. Meiosis within zygospore.

C. VEGETATIVE HYPHAE:Haplophase; no dikaryophase except in fused

gametangia; aseptate.

PHYLUM CHARACTERISTICS

Asexual Reproduction: -spores are produced by sporangia at the ends of modified, erect hyphae

Sexual Reproduction: -two opposite mating types of hyphae join to produce gametangia that produce a diploid zygospore (thick walled spore)-the zygospore undergoes meiosis before germination and produces a haploid mycelium                                                   

D. CELL WALLS: Chitin and chitosan.

E. ECOLOGY: Free-living to parasitic.  Free-living forms mainly terrestrial saprobes.  Parasites mainly of insects, but of other animals, too.  Some parasitic on microbial eukaryotes.

production of asexual aplanospores,

• fusion of gametangia to produce zygospores • walls of chitin and chitosan; • asexual development seems to be from many-spored sporangia, through sporangia with a much-reduced number of spores,

• to one-spored sporangiola which function as conidia.

CLASS ZYGOMYCETES

- Filamentous; - aplanospores produced in globose,- multinucleate sporangia, - narrow cylindrical sac-like merosporangia, - few-spored sporangiola or singly as conidia; - zygospores often thick-walled, - black and warty resting spores; - large terminal chlamydospores common in mycorrhizal forms. - Saprophytic "pin molds".

ORDER MUCORALES

Mucor

Rhizopus

Pilobolus kleinii Hat Thrower

Chaetocladium brefeldii

Choanephora cucurbitarum

Mortierella

Phycomyces blakesleeanus

- Filamentous

- coenocytic

- saprobic and mycorrhizal

- zygospores produced in underground sporocarp.

ORDER ENDOGONIALES

Densospora , Endogone, Pteridiospora, Sclerogone, Youngiomyces.

- Filamentous- hyphae with septa which have a lens-shaped cavity; - asexual reproduction by merosporangium of bispores.  - Zygospore ornamented. - Parasites of fungi, especially Mucorales.

Dimargaris, Dispira, Spinalia, Tieghemiomyces.

ORDER DIMARGARITALES

- Filamentous - some saprophytic, but mostly insect parasites- vegetative phase tending to break up into segments (hyphal bodies)- asexual reproduction by forcibly discharged uni- or multinucleate conidia- zygospores smooth or ornamented.

ORDER ENTOMOPHTHORALES

Entomophthora, Condiobolus, Completoria, Meristacrum, Neozygites..

Basidiomycota

Club fungi

Amanita rubrovaginata

Gymnosporangium juniperi-virginianae

Tilletia controversa

- Basidiomycetes - the club fungi, about 22,300 species

1. Includes mushrooms, toadstools, puffballs, shelf fungi,

rusts, bird's nest fungi and smuts2. Characterized by perforate septate hyphae

and the production of a basidium (club) following sexual reproduction. The basidia (pl. of basidium) occur in a mycelium called a basidiocarp and they produce external basidiospores

3. See your next slide for a typical life cycle

Basidiomycota

Basic structure of Club fungi

cap

Annulus

Gills

Stalk

Vulva

Phylum ascomycota