MYCORRHIZAE: DEFINITION, TYPES, BENEFITS - BIOLOGY - 2025

The mycorrhizae are associations between fungi and the roots of trees. It is a symbiosis because it provides benefits for both parties involved. In this case, the plants increase their absorption range thanks to the fungi, while these receive nutrients synthesized by the vegetables.

A single fungus can join more than one plant, forming a wide network. In fact, many forests are connected through mycorrhizae. In this regard, studies have been carried out that show that mycorrhized trees are capable of living longer than those without mycorrhization.

Ectomycorrhizal mycelium (white) associated with the roots of Picea glauca (brown).

In other cases, the relationship between the plant and the fungus is such that neither species can survive without the other. An example of this is orchids.

Two types of mycorrhizae are distinguished: ectomycorrhizae and endomycorrhizae. The former are those in which the fungus surrounds the roots of the plants, while in the latter the fungus penetrates the roots of the plant. Ectomycorrhizae are common in forests.

Types of mycorrhizae

There are two types of mycorrhizae according to the relationship that the fungus establishes with the roots of the plants: ectomycorrhizae and endomycorrhizae.

Ectomycorrhizae

Ectomycorrhizae are those in which the hyphae of the fungi surround the roots of the plants, without penetrating them.

This type of association occurs mainly in forests. There, the fungi grow to the surface of the soil, where they form a kind of fruit, known as mushrooms and truffles.

It should be noted that a single fungus can create hundreds of these fruits, which grow forming a circumference.

Endomycorrhizae

Endomycorrhizae occur when the hyphae of fungi penetrate the roots. The union is such that the cells of the fungi interpenetrate with the cells of the plants.

Unlike ectomycorrhizae, endomycorrhizae do not produce visible structures or "fruits." This type of association occurs in smaller plants.

Plants and mycorrhiza dependency

There are different levels at which plants depend on mycorrhizae. Studies in the area show that plants can have high concentrations of mycorrhizae, intermediate concentration or absence thereof.

Plants with high concentrations of mycorrhiza are dependent on fungi for survival. This is a mandatory relationship, since the plant would die without the sustenance of the mycorrhiza.

Plants with intermediate concentrations of mycorrhiza do not depend on this type of association, but take advantage of it to improve their conditions (such as resistance to drought and certain diseases). This relationship is optional.

Lastly, there are plants whose roots resist the formation of associations with fungi. This occurs when the soil conditions are good enough (so that the plant does not need the advantages of mycorrhizae) or when the plant is young and stable (so it does not require additional sustenance).

Benefits: Importance of mycorrhizae

Mycorrhizae generate hundreds of advantages that can be evidenced in different fields. Thus, mycorrhizae bring benefits for plants, for soils, for fungi and for humans.

Benefits for plants

Mycorrhizae form a network of filaments that increase the degree of absorption of the roots of the plants. For example, the fungus attached to a plant can spread for hundreds of meters, which causes the plant to be in contact with more water and nutrients.

Fungi are responsible for decomposing organic matter, from which they obtain essential minerals, such as nitrogen and phosphorus. These nutrients are sent to the plant through the roots. By themselves, plants might not be able to break down these substances.

In addition to this, mycorrhizae make plants capable of resisting certain conditions that they could not bear if they were not connected to fungi. For example, thanks to fungi, plants survive in times of drought and create resistance to certain soil pathogens.

Other advantages of mycorrhizae for plants are:

1. They help plants grow faster and stronger.
2. They favor flowering and fruit production in the plant.
3. They increase the tolerance of the plant to the salinity of the substrate.
4. They reduce the incidence of diseases.
5. They protect the plant from some predators, such as earthworms.
6. They increase the transfer of carbon between trees, even among those of different species.
7. They prolong the life of certain plant species.

Benefits for fungi

Mycorrhizae not only benefit plants, but also generate benefits for fungi. Fungi are organisms that do not perform photosynthesis, so they cannot synthesize products autonomously. In this sense, they depend on other individuals to feed themselves.

By forming mycorrhizae, the fungus receives nutrients produced by plants, such as carbohydrates.

Benefits for soils

In general, the presence of mycorrhizae makes the soils more fertile. Mycorrhizae:

1. They prevent the erosion of the substrate by establishing connections in the subsoil.
2. They increase the circulation of nutrients in the substrate, which creates more fertile soils.

Benefits for humans

Mycorrhizae are important in economics and medicine. Here are some of the aspects in which these associations intervene in human life.

1. The fruits of ectomycorrhizae (mushrooms and truffles) provide nutritional values. For this reason, they are commercialized, which makes them important from an economic point of view.
2. Many of these fruits also have medicinal properties, which is why they are used in the pharmaceutical industries.
3. By increasing the absorption of nutrients from plants, mycorrhizae increase the nutritional value of products, such as fleshy fruits and dried fruits.

References

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