Ectotrophic mycorrhiza is a specific type of symbiotic relationship that occurs between certain fungi and the roots of plants. In this mutualistic association, the fungus forms a mantle or sheath around the root tips without penetrating the root cells. This unique interaction provides various benefits to both the fungus and the host plant.
Key Facts
- Definition: Ectotrophic mycorrhiza is a symbiotic relationship between certain fungi and the roots of plants, where the fungus forms a mantle or sheath around the root tips without penetrating the root cells.
- Plant species: Ectomycorrhizas form on the roots of around 2% of plant species, usually woody plants, including species from the birch, dipterocarp, myrtle, beech, willow, pine, and rose families.
- Fungal structure: In ectotrophic mycorrhiza, the fungus forms a sheath or mantle around the root tips, creating a protective layer. The fungal hyphae extend into the surrounding soil, increasing the absorption surface area of the roots.
- Nutrient exchange: The fungus in ectotrophic mycorrhiza absorbs nutrients from the soil, such as phosphorus, ammonium, and zinc, and transfers them to the plant. In return, the fungus receives carbohydrates from the host plant.
- Benefits: Ectotrophic mycorrhizal associations can benefit plants by increasing nutrient uptake, improving tolerance to adverse conditions like drought and high temperatures, and providing some protection against soil-borne diseases.
Definition
Ectotrophic mycorrhiza, also known as ectomycorrhiza, refers to the symbiotic relationship between fungi and plant roots, where the fungal hyphae form a protective sheath or mantle around the root tips. Unlike other types of mycorrhizal relationships, such as arbuscular mycorrhiza, the fungus does not penetrate the root cells in ectotrophic mycorrhiza.
Plant Species
Ectomycorrhizas are found on the roots of approximately 2% of plant species, primarily woody plants. This includes species from various plant families, including birch, dipterocarp, myrtle, beech, willow, pine, and rose families. The symbiotic association between these fungi and plants is particularly common in forest ecosystems.
Fungal Structure
In ectotrophic mycorrhiza, the fungus forms a sheath or mantle around the root tips, creating a protective layer. The fungal hyphae extend into the surrounding soil, increasing the absorption surface area of the roots. This extensive network of hyphae enhances the plant’s ability to acquire nutrients and water from the soil.
Nutrient Exchange
One of the key aspects of ectotrophic mycorrhizal associations is the exchange of nutrients between the fungus and the plant. The fungus absorbs nutrients, such as phosphorus, ammonium, and zinc, from the soil and transfers them to the plant through the hyphal network. In return, the fungus receives carbohydrates, primarily in the form of sugars, from the host plant. This nutrient exchange is essential for the growth and development of both the fungus and the plant.
Benefits
Ectotrophic mycorrhizal associations offer several benefits to both the fungus and the host plant.
Firstly, the fungal sheath or mantle provides a protective barrier around the root tips, offering some defense against soil-borne pathogens and reducing the risk of infection. Additionally, the extensive hyphal network increases the surface area for nutrient absorption, enhancing the plant’s ability to acquire essential elements from the soil.
Moreover, ectotrophic mycorrhizal fungi can improve the plant’s tolerance to adverse environmental conditions. They can enhance the plant’s resistance to drought stress by increasing water uptake and reducing water loss through transpiration. These fungi can also help plants withstand high temperatures by improving heat tolerance mechanisms.
Furthermore, ectotrophic mycorrhizal associations contribute to nutrient cycling and ecosystem functioning. The fungal hyphae play a vital role in the decomposition of organic matter, releasing nutrients back into the soil for uptake by other organisms.
In summary, ectotrophic mycorrhiza is a symbiotic relationship between fungi and plant roots, characterized by the formation of a sheath or mantle around the root tips. This association benefits both the fungus and the host plant by facilitating nutrient exchange, improving tolerance to adverse conditions, and contributing to ecosystem functioning.
Sources:
- “Ectomycorrhiza” – Wikipedia. Available at: https://en.wikipedia.org/wiki/Ectomycorrhiza
- “Ectotrophic mycorrhiza” – Britannica. Available at: https://www.britannica.com/science/ectotrophic-mycorrhiza
- “Mycorrhizae” – University of Wisconsin-Madison Division of Extension. Available at: https://hort.extension.wisc.edu/articles/mycorrhizae/
FAQs
What is ectotrophic mycorrhiza?
Ectotrophic mycorrhiza is a symbiotic relationship between certain fungi and the roots of plants, where the fungus forms a mantle or sheath around the root tips without penetrating the root cells.
Which plant species form ectomycorrhizas?
Ectomycorrhizas form on the roots of around 2% of plant species, usually woody plants, including species from the birch, dipterocarp, myrtle, beech, willow, pine, and rose families.
How does the fungal structure in ectotrophic mycorrhiza differ from other mycorrhizal relationships?
In ectotrophic mycorrhiza, the fungus forms a sheath or mantle around the root tips, creating a protective layer. The fungal hyphae extend into the surrounding soil, increasing the absorption surface area of the roots.
How do the fungus and the plant exchange nutrients in ectotrophic mycorrhiza?
The fungus in ectotrophic mycorrhiza absorbs nutrients from the soil, such as phosphorus, ammonium, and zinc, and transfers them to the plant. In return, the fungus receives carbohydrates from the host plant.
What are the benefits of ectotrophic mycorrhizal associations for plants?
Ectotrophic mycorrhizal associations can benefit plants by increasing nutrient uptake, improving tolerance to adverse conditions like drought and high temperatures, and providing some protection against soil-borne diseases.