Introduction to the Fungi

Learning Objectives and Disclosure Information

• Upon completion of this workshop, participants should be able to:

• Set up a sampling station to collect airborne pollen and fungal spore

• Recognize the most common types of pollen found in the atmosphere

• Recognize the most common types of fungal spores found in the atmosphere

• No conflicts to disclose

Fungi are eukaryotic organisms that are neither plant nor animal

Fungi include molds

Mushrooms

Puffballs

Bracket Fungi

Fungi can be unicellular such as yeast

Fungi usually have a thread like body made up of hyphae

Hyphae make up the mycelium

Hyphae also make up the structure of fruiting bodies such as mushrooms

Fungal Life Styles

• Fungi are absorptive heterotrophs

• As absorptive heterotrophs they exist as– Pathogens– Mutualistic symbionts– Saprobes

Common Human Pathogen

Apple-Cedar Rust A Destructive Plant Pathogen

Lichens are symbiotic organisms composed of an alga and a fungus

The Majority of Fungi Are Saprobes

Most of the common airborne fungi are saprobes naturally occurring on leaf surfaces, decaying plant material, or in soil

Fungi reproduce by spores

Spores can result from sexualor asexual reproduction

Mycelium

Sexual Spores

Mycelium

Asexual Spores

Spore Release Mechanisms

• PASSIVE: Frequently related to wind speed and turbulence – include members of the “Dry Air Spora” which peak in the afternoon

• ACTIVE: Generally require moisture – common mechanism for ascospores and basidiospores– Basidiospores most abundant in predawn hours– Ascospores most abundant during or following rain;

however, a number of ascospores only require high humidity and are abundant in predawn hours

Sporangium Conidia on hyphae

Sporangiospore or just “spore”

Conidium

Sporangiophore Conidiophore

Types of Asexual Spores

Rhizopus Sporangium

Chains of Conidia

ZYGOMYCOTA -- Zygospores

ASCOMYCOTA -- Ascospores

BASIDIOMYCOTA -- Basidiospores

ASEXUAL FUNGI -- Conidia - mold spores

Asexual Fungi

• Constitute an artificial group based only on asexual spores

• Most are members of the Ascomycota with a small percent members of the Basidiomycota

• Also called– Deuteromycetes– Imperfect Fungi (Fungi Imperfecti)– Mitosporic Fungi– Anamorphic Fungi– Mold Spores

Members of the Zygomycota produce asexual spores in a sporangium

The zygospore (zygosporangium) is the characteristic sexual structure of the Zygomycota

Characteristic sexual structure of the Ascomycota is the ascus containing 8 ascospores

Ascomycota

• Many members of the Ascomycota develop asci within a fruiting body.

• Fruiting bodies often called ascocarps

• Ascocarps can be– Flask-shaped– Cup-shaped– Other

Cup-shaped fruiting body

Morels are also cup-shaped fruiting body

Asci with ascospores from a morel

Abundant Airborne Ascospores Following Rain

Airborne Ascospores Still in Group of 8

Basidiomycota• The most conspicuous fungi in

the environment• Basidiospores are typically

produced in a large fruiting body such as– Mushrooms

– Bracket Fungi

– Puffballs

Characteristic spores are basidiospores and four

basidiospores are produced externally on basidia

Basidia line the pores of bracket fungi and the gills of mushrooms

Single Basidium with 4 Basidiospores

Basidiospores are small and single-celled often with an asymmetric attachment peg

Rusts and Smuts

• Basidiomycota also includes two groups of fungi that lack fruiting bodies

• Rust fungi and smut fungi

• Important pathogens on both native and cultivated plants

Stem Rust of Wheat

Loose Smut of Wheat

Asexual Fungi