Transcript Basidiomycetes

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.
Basidiomycetes
Characteristics:
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
Basidiomycetes
Characteristics:
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 sporophore
ii. Important genera – Polyporus, Fomes
Order Agaricales – the mushrooms
i. Hymenium lines gills (lamellae)
ii. Important genera – Armillaria, Agaricus
Aphyllophorales
Agaricales
Basidiomycetes
5. 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
Primary hyphae
Primary hyphae
Secondary hyphae
Tertiary 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
The Rusts
These 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 produced
Alternative 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