Rusts and Smuts also Zygomycetes

What phylum are Rusts and Smuts in?   

Basidiomycota.

Do Rusts have basidiocarps?   

No, they lack basidiocarps but have basidia.

What type of hyphae do Rusts have?   

Dikaryotic hyphae.

How many hosts do Rusts often require?  

Two (heteroecious).

How many spore stages can Rusts have?  

 Five.

List the five possible spore stages of Rusts.

Spermatia, Aeciospore, Urediniospore, Teliospore, Basidiospore.

What does “macrocyclic” mean in Rusts?  

 All five spore stages are present.

What does “demicyclic” mean in Rusts?   

Four spore stages (no urediniospores).

What does “microcyclic” mean in Rusts?  

Only teliospores and basidiospores are produced.

Stage 0: What is a spermagonium (pycnium)?   

A flask-shaped structure holding spermatia and receptive hyphae; where plasmogamy begins.

What happens during plasmogamy in Rusts?  

 Spermatia from one mating strain fuse with receptive hyphae of the opposite strain to form dikaryotic cells.

Stage I: What are aecia?  

 Cup-shaped structures that produce aeciospores (dikaryotic, non-repeating).

What is the function of aeciospores?   

They infect the telial host.

Stage II: What are uredinia?   

Structures producing dikaryotic, repeating urediniospores.

What is the function of urediniospores?   

They reinfect the same host and spread the fungus rapidly.

Stage III: What are telia?   

Structures that produce thick-walled teliospores for overwintering.

What is the function of teliospores?  

 They germinate to form basidia.

Stage IV: What are basidia?  

 Structures that produce haploid basidiospores after teliospores germinate.

What do basidiospores infect?  

 The aecial host (starting the cycle again).

What does “heteroecious” mean?  

 The rust requires two different hosts to complete its life cycle.

What does “autoecious” mean?  

 The rust completes its life cycle on a single host.

Example of a macrocyclic, heteroecious rust.  

 Fir broom rust.

Example of a heteroecious rust involving pine and oak.  

 Fusiform rust.

Example of a heteroecious rust involving cedar and apple.  

 Cedar-apple rust.

What phylum are Smuts in?   

Basidiomycota.

Example of a Smut fungus.  

Basidiomycota.

What phylum is Phycomyces in?   

Zygomycota.

How does Phycomyces reproduce asexually?  

 Using sporangia.

What is the difference between conidia and sporangia?   

Conidia are asexual spores of Ascomycetes; sporangia are asexual structures of Zygomycetes.

What are zygospores?  

 Thick-walled sexual spores of Zygomycetes formed by fusion of compatible hyphae.

What are the ecological roles of Zygomycetes?   

Decomposers and opportunistic pathogens.