Basidiomycetes

Characteristics:

1. Septate mycelium

2. Basidia and basidiospores

3. Clamp connections. Not all Basidiomycetes produce these, but when a fungus does it will always be a basidiomycete.

BasidiomycetesCharacteristics:

4. Two main groups, based on morphology of basidia.

a. Basidia are septate and deeply lobed

Order Uredinales – the rusts

i. Produce all five spore stages – aeciospores, uredospores, teliospores, basidiospores and spermatia (aka pycniospores)

ii. Important genera – Puccinia, Gymnosporangium

Order Ustilaginales – the smuts

i. Produce only basidiospores and teliospores

ii. Important genera – Ustilago, Tilletia

Order Uredinales Order Ustilaginales

BasidiomycetesCharacteristics:4. Two main groups, based on morphology of basidia.

b. Basidia are unicellular, non-septate: wood decay fungi

Order Aphyllophorales (aka Polyporales) – the bracket fungi

i. Hymenium lines small pores on underside of sporophoreii. Important genera – Polyporus, Fomes

Order Agaricales – the mushroomsi. Hymenium lines gills (lamellae)ii. Important genera – Armillaria, Agaricus

Aphyllophorales Agaricales

Basidiomycetes5. Three types of hyphae

a. Primary hyphae – develops from a germinating basidiospore. Nuclear status = n

b. Secondary hypha – results from fusion of two primary hyphae. Yields a n+n cell that continues to grow as a n+n hyphae

c. Tertiary hypha – exactly the same as secondary hypha. n+n However it has thick walls that enable production of fleshy and wood sporophores

Primary hyphae Primary hyphae

Secondary hyphae

Tertiary hyphae

The RustsThese are obligate parasites. Generally these require two host to

complete their lifecycle. Primary hosts – the host on which basidia and basidiospores are

produced.Alternate host – the other host in the life cycle on which

spermagonia and aecia are producedAlternative host – the host that a pathogen can infect in place of

the primary or alternate hosts.

Heteroecious – organisms with a primary and alternate host.Autoecious – organisms that have only a single (primary) host.

Macrocyclic rust – long cycle rust. Produce all 5 spore types. Demicyclic rust – medium cycle rust. Omits uredia.Microcyclic rust – short cycle rusts. Produces basidiospores,

teliospores and spermatia.

Wheat stem rust, caused by Puccinia graminis tritici

Cedar apple rust, caused by Gymnosporangium juniperi-virginianum lacks the uredia stage = no repeating stage

The Smuts

Unique characteristics of smuts (vs. rusts)

a. They are not obligate parasites. We can grow them in culture.

b. They show a very high degree of selectivity. They attack not only certain host but certain tissues of the host.

c. Have only tow spore types: basidiospores and teliospores.

Example: corn smut, caused by Ustilago maydis

Review• Wheat stem rust – all

spore types

• Cedar apple rust – lacks ureida

• Coffee rust – no aecial stage

• Smuts – basidiospores + teliospores only