What is the Difference Between Autoecious and Heteroecious Rust

The main difference between autoecious and heteroecious rust is that autoecious rust only contains a primary host, whereas heteroecious rust contains both primary and alternate rust. 

Autoecious and heteroecious rust are two rust types. Rust is a plant disease, and a pathogenic fungus of the order Pucciniales causes rust. 

Key Areas Covered

1. What is Rust
– Definition, Features, Importance
2. What is Autoecious Rust
– Definition, Features, Importance
3. What is Heteroecious Rust
– Definition, Features, Importance
4. Similarities Between Autoecious and Heteroecious Rust
– Outline of Common Features
4. Difference Between Autoecious and Heteroecious Rust
– Comparison of Key Differences

Key Terms 

Autoecious Rust, Heteroecious Rust

What is Rust

Rust is a plant disease caused by fungi. Approximately 7,000 species cause rust in plants. Puccinia is the most common genus of rust. However, rust fungi are diverse and affect many types of plants. However, each species of rust fungi has a narrow range of hosts. Therefore, it is not transmitted to the non-host plants. Also, most of the rust fungi cannot grow in pure cultures. Meanwhile, some rust fungi infect two different hosts in different life cycle stages. Rust fungi have five different spore states: spermatia (0), aeciospores (I), urediniospores (II), teliospores (III), and basidiospores (IV). 

• Spermatia (0): The gametes of the heterothallic rusts. They are haploid.
• Aeciospores (I): The non-repeating, dikaryotic, asexual spores that infect the primary host.
• Urediniospores (II): The repeating, dikaryotic vegetative spores. They form auto-infection on the primary host. Also, they are a prominent sign of infection in the primary host. The color of the urediniospores is red or orange. 
• Teliospores (III): The dikaryotic spores that survive in unfavorable conditions. Also, they do not infect plants directly. Their germination produces basidiospores and basidia.
• Basidiospores (IV): They form from teliospores. Importantly, they are wind-borne and infect alternate hosts. 

These states are morphologically and cytologically different from each other. Importantly, each spore state is very host-specific. Typically, they infect only one type of host. Furthermore, rusts are obligate plant pathogens, and they infect living plants only. 

What is Autoecious Rust

Autoecious rust is a type of rust that infects only a primary host. Aeciospores are the stage of rust that infects the primary host. Therefore, autoecious rust in non-host alternating. Examples of autoecious rust include Puccinia porri. Importantly, they complete all life cycle parts on a single host.

Figure 1: Puccinia porri

What is Heteroecious Rust

Heteroecious rust is another type of rust that infects both the primary and the alternate host. The primary and the alternate hosts are unrelated hosts. Also, aeciospores infect the primary host, while basidiospores infect the alternative host. Here, both types of hosts are required for the completion of the life cycle of the heteroecious rust. Cedar-apple rust and quince rust are examples of heteroecious rust.

Figure 2: Cedar-apple rust

Similarities Between Autoecious and Heteroecious Rust

• Autoecious and heteroecious rust are two rust types that occur in plants.
• They are plant diseases caused by pathogenic fungi. 

Difference Between Autoecious and Heteroecious Rust

Definition

Autoecious rust refers to completing the entire life cycle on a single species of host. In contrast, heteroecious host refers to passing through the different stages in the life cycle on alternate and often unrelated hosts.

Type of Host

Autoecious rust live in a primary host, while heteroecious rust live in both primary and alternate host. 

Host Alternating

Autoecious rust is non-host alternating, while heteroecious rust is host alternating.  

Examples

Puccinia porri is an example of autoecious rust, while cedar-apple rust and quince rust are examples of heteroecious rust. 

Conclusion

In brief, autoecious and heteroecious rust are two types of rust that cause plant diseases. Therefore, they are pathogenic fungi. Autoecious rust completes its life cycle on a single species of host called the primary host. Therefore, it is non-host alternating. In comparison, heteroecious rust passes its life cycle in primary and alternate hosts. Hence, it is host alternating. However, the main difference between autoecious and heteroecious rust is their alternating of the host. 

References:

1. Rust fungi. Rust Fungi – an overview | ScienceDirect Topics. (n.d.). 

Image Courtesy:

1. “Prei winter roest (Puccinia allii on Allium porrum)” By Rasbak – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Cedar apple rust 4159 ” By Ronincmc – Own Work (CC-BY SA 4.0) via Commons Wikimedia