What is the Difference Between Photobiont and Mycobiont

The main difference between photobiont and mycobiont is that photobiont is the algal partner in a lichen whereas mycobiont is the fungal partner. Furthermore, the main function of the photobiont is to undergo photosynthesis, providing food for the fungi while the mycobiont is responsible for providing shelter and absorbing water and nutrients for the algae.

Photobiont and mycobiont are the two types of organisms involved in the formation of a lichen. Generally, a lichen is a composite organism that arises due to mutualistic relationships between different species.

Key Areas Covered

1. What is Photobiont
     – Definition, Characteristics, Importance
2. What is Mycobiont
     – Definition, Characteristics, Importance
3. What are the Similarities Between Photobiont and Mycobiont
     – Outline of Common Features
4. What is the Difference Between Photobiont and Mycobiont
     – Comparison of Key Differences

Key Terms

Algae, Filamentous Fungi, Lichen, Mutualistic Relationship, Mycobiont, Photobiont

What is Photobiont

Photobiont is the photosynthetic partner in a lichen. It maintains a mutualistic relationship with the fungal component of the lichen. Generally, either green algae or cyanobacteria can serve as the photosynthetic partner. Here, phycobionts refer to the algal photobionts while cyanobionts refer to the cyanobacterial photobionts. Usually, 90% of photobionts are algae while the rest of them are cyanobacteria. Also, Trebouxia, Trentepohlia, Pseudotrebouxia, and Myrmecia are the most common genera of algae found in lichens. On the other hand, Nostoc is the most common genus of cyanobacteria in lichens.

Figure 1: Lung Lichen

Especially, photobiont contains chlorophyll a in order to undergo photosynthesis. Therefore, the main function of photobiont is to produce food for the fungal component in the lichen.

What is Mycobiont

Mycobiont is the fungal component in a lichen. The two main phyla of fungi involved in the formation of lichen are Ascomycetes and Basidiomycetes. Therefore, the lichens associated with the respective phyla of fungi are known as ascolichens and basidiolichens. Generally, lichens are considered as a successful way for symbiotic fungi to derive their nutrients. Significantly, the fungal component, which is filamentous, forms the thallus of the lichen. Moreover, the algal component lives among the filaments of the fungus. Also, two or three algal components can live with the fungal component of the lichen.

Figure 2: Lichen – Cross Section

Therefore, the main function of the fungus in a lichen is to provide shelter to the algal component or the photobiont. Additionally, it absorbs water and nutrients required for the growth of the photobiont.

Similarities Between Photobiont and Mycobiont

• Photobiont and mycobiont are the two different species responsible for the formation of a lichen.
• Both types of organisms maintain a mutualistic relationship between them.
• Also, both receive benefits from their symbiotic relationship.

Difference Between Photobiont and Mycobiont

Definition

A photobiont refers to the photosynthetic component of a lichen, which may be either a green alga or a cyanobacterium, while mycobiont refers to the fungal component of a lichen. Thus, this is the main difference between photobiont and mycobiont.

Type of Organism

While photobiont can be either a green algae or cyanobacteria, mycobiont is a filamentous fungus.

Role

Moreover, photobiont is responsible for providing food for the fungus by undergoing photosynthesis while mycobiont is responsible for providing shelter and absorbing water and nutrients for the photobiont. Hence, this is the functional difference between photobiont and mycobiont.

Conclusion

Photobiont is the algal component in a lichen. It can be either green algae or cyanobacteria, containing chlorophyll a. Therefore, it is responsible for undergoing photosynthesis in order to provide food for the fungal component in the lichen. In comparison, mycobiont is the fungal component of the lichen. It is mainly a filamentous fungus, absorbing water and nutrients for the algae while sheltering the algae. Hence, the main difference between photobiont and mycobiont is the type of organism and their role in the lichen.

Reference:

1. Lepp, Heino. “What Is a Lichen? – Lichens.” AUSTRALIAN NATIONAL HERBARIUM, Australian National Botanic Gardens and Australian National Herbarium, 7 Mar. 2011, Available Here.

Image Courtesy:

1. “Lobaria pulmonaria 01” By H . Zell – Own work (CC BY-SA 3.0) via Commons Wikimedia                                              2. “Lichen Cross Section Diagram” By Jdurant – Own work (CC BY-SA 3.0) via Commons Wikimedia