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Characteristics
Spore Stages

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Phylum: Basidiomycota
Class: Teliomycetes
O
rder: Uredinales 
(Rust Fungi)


teliospores



Uredinales: Characteristics
        • Basidia septate
        • Basidiocarp absent
        • Basidia formed by the germination of a teliospore
          (thick-walled spore in which karyogamy occurs)

There may be as many as 5 spore stages in the life cycle of some rust fungi. Rust fungi with all 5 
spore stages are termed macrocyclic rusts. The 5 spore stages are produced in a definite sequence. 

If all spore stages are produced on a single host species, the rust fungus is described as autoecious. If the spore stages are produced on two taxonomically distinct hosts, the rust fungus is described as heteroecious. In this case, certain spore stages are produced on one host and the remaining spore stages on the second host, termed the alternate host




Rust Spore Stages and Spores
 0 
Spermagonium
(Pycnium)
Spermatium
(Pycniospore)
I
Aecium Aeciospore
II
Uredium
(Uredinium)
Uredospore
(Urediniospore)
III
Telium Teliospore
IV
Basidium Basidiospore



Rust spermagonia with a longitudinal section on the right showing the receptive hyphae and spermatia.

 

Schematic drawing of a spermagonium. Spermatia and receptive hyphae are of one 
mating type designated either + or -.  Spermatia of one mating type fertilize receptive 
hyphae of the other mating type.



aecia
aecia
aecia

Examples of aecia of different rust fungi.


Longitudinal section of an aecium and aeciospores.

 
 
Schematic section of an aecium and aeciospores.

Spermagonia and aecia are produced on the same host species for heteroecious rust 
fungi and the aeciospores infect the alternate host species.



uredia
uredia

Examples of uredia of different rust fungi.
 

Uredia with urediospores.  Urediospores can reinfect the host species on which they 
are formed.  This is often called the repeating stage of a rust fungus. 
 

Schematic of a uredium with urediospores. 



 
telia

telia

telia

Examples of telia of 
different rust fungi.


 
 

Longitudinal section of a telium.
 
 

Schematic of a telium with teliospores 


Telia that are long and gelatinous are referred to as telial horns.  Teliospores are embedded in in telial horns. 

 
 
telia columns
Telia that are long and slender are referred to as telial columns. Telial columns are composed of many one-celled teliospores. 

 
 

Teliospores of different species of rust fungi.
 

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This website was prepared by Becky Bernard.
Last update 04 February 2008 by M.J. Munster