The key difference between lichen and mycorrhizae is that lichen is a mutualistic association that exists between an algae/cyanobacterium and a fungus, while mycorrhiza is a type of mutualistic association occurring between roots of a higher plant and a fungus.
Mutualism is one of the three types of symbiosis that occurs between two different species of organisms. Unlike the other two types, mutualism benefits both partners that are in the association. Lichen and mycorrhizae are two common examples of mutualistic associations. Both are ecologically important relationships. Two parties of the lichen are algae or cyanobacterium and a fungus. On the other hand, two parties of the mycorrhizae are roots of a higher plant and a fungus.
CONTENTS
1. Overview and Key Difference
2. What is Lichen
3. What is Mycorrhizae
4. Similarities Between Lichen and Mycorrhizae
5. Side by Side Comparison – Lichen vs Mycorrhizae in Tabular Form
6. Summary
What is Lichen?
Lichen is a mutualistic relationship that exists between an algae/cyanobacterium and a fungus. In this association, one party is responsible for the production of food by photosynthesis while the other party is responsible for the absorption of water and providing shelter. Photobiont is the photosynthetic partner of the lichen. It is responsible for the production of carbohydrates or food by photosynthesis. It can be a green alga or a cyanobacterium. Both are able to carry out photosynthesis since they have chlorophylls.
Figure 01: Lichen
However, when comparing green algae and cyanobacteria, algae contribute more towards forming lichens with fungi than cyanobacteria. Mycobiont is the fungal partner of the lichen. It is responsible for the absorption of water and providing shade to the photobiont. Usually, fungi of ascomycetes and basidiomycetes form this kind of symbiotic association with algae or with cyanobacteria. Generally, in lichen, only one species of fungi can be seen – it can be either an ascomycete or a basidiomycete. Lichens can be seen on tree bark, exposed rock, and also as a part of biological soil crust. Not only that, lichens can survive under extreme environments such as frozen north, hot deserts, rocky coasts, etc.
Lichens provide several important functions. They are very sensitive to their surroundings. Thus, they can indicate phenomena such as pollution, ozone depletion, metal contamination, etc., acting as environmental indicators. Furthermore, lichens produce natural antibiotics that can be used to make medicines. Furthermore, lichens are useful for making perfumes, dyes, and herbal medicines.
What is Mycorrhizae?
Mycorrhiza is another example of a mutualistic relationship. It occurs between roots of a higher plant and a fungus. Fungus inhabits the roots of higher plant without harming the roots. The higher plant provides food to the fungus while fungus absorbs water and nutrients from the soil to plant. Therefore, this mutualistic interaction provides benefits to both partners. Mycorrhizae are ecologically important. It is because when the plant roots do not have access to the nutrients, fungal hyphae can grow several meters and transport water and nutrients, especially nitrogen, phosphorus, potassium to the roots. Hence, nutrient deficiency symptoms are less likely to occur in plants which are in this symbiotic association. About 85% of the vascular plants possess endomycorrhizal associations. Also, fungus protects the plant from root pathogens. Therefore, mycorrhizae are very important associations in the ecosystems.
Figure 02: Mycorrhizae
Ectomycorrhizae and endomycorrhizae are two main types of mycorrhizae. Ectomycorrhizae do not form arbuscules and vesicles. Moreover, their hyphae do not penetrate into the cortical cells of the plant root. However, ectomycorrhizae are really important since they help plants to explore nutrients in the soil and protect plant roots from root pathogens. Meanwhile, in endomycorrhizae, fungal hyphae penetrate into the cortical cells of the plant roots and form vesicles and arbuscules. Endomycorrhizae is more common than ectomycorrhizae. Fungi from Ascomycota and Basidiomycota are involved in forming ectomycorrhizal association while fungi from Glomeromycota are involved in forming endomycorrhizae.
What are the Similarities Between Lichen and Mycorrhizae?
- Lichen and mycorrhizae are two types of mutualistic symbiotic relationships that exist between two different species.
- Moreover, both partnerships always involve a fungus.
- Both parties are benefitted in both relationships.
- Furthermore, both lichen and mycorrhizae are ecologically important for the ecosystem sustenance.
What is the Difference Between Lichen and Mycorrhizae?
Lichen and mycorrhizae are two common mutualistic relationships. Lichen occurs between a fungus and either cyanobacterium or green alga while mycorrhiza occurs between a fungus and plant roots. So, this is the key difference between lichen and mycorrhizae. Furthermore, mostly ascomycetes and basidiomycetes participate in forming lichens, while basidiomycetes, glomeromycetes and few ascomycetes participate in forming mycorrhizae. Therefore, this too is a difference between lichen and mycorrhizae.
Summary – Lichen vs Mycorrhizae
Lichen is an association between an alga / or a cyanobacterium and a fungus. On the other hand, mycorrhiza is an association between a fungus and the roots of a higher plant. So, this is the key difference between lichen and mycorrhizae. Both associations are common examples of mutualism. And they have an ecological significance as well.
Reference:
1. “What Is a Lichen?” The British Lichen Society, Available here.
2. “Mycorrhiza.” Australian National Botanic Gardens, Available here.
Image Courtesy:
1. “Parmelia Lichen on our Japanese Lace leaf maple” By J Brew (CC BY-SA 2.0) via Flickr
2. “Pine (slash pine) mycorrhizae 6 Sep 1964” By Scot Nelson (Public Domain) via Flickr