Table of Contents
Meaning
A mycorrhiza is a symbiotic relationship between a fungus and a root system. A network of fungus filaments surrounds the developing root or reaches the root cells directly. The hyphae possess a relatively broad surface area, which allows them to collect water and mineral ions from a significantly more amount of soil than the root. The roots receive water and minerals from the fungus, and the mycorrhizae receive sugars and N-containing components from the roots.
Certain plants require an association with mycorrhizae. For example, mycorrhizae are necessary for the germination and establishment of Pinus seeds.
When two organisms form a mycorrhizal relationship, the fungus colonises the host plant’s root tissues either intracellularly like in arbuscular mycorrhizal fungi (AMF or AM), or extracellularly like in ectomycorrhizal fungi. Mycorrhizae may associate parasitically with host plants depending on the species or the environment. Often the association is mutualistic.
Types of Mycorrhiza
The two main types of mycorrhizae are ectomycorrhizae and endomycorrhizae. They are categorised according to where the fungi colonise on the plants.
Ectomycorrhiza
Ectomycorrhiza, also known as EcM, usually develops connections between woody plants (like beech, birch, willow, oak, pine, fir and spruce) and fungi belonging to the Ascomycota, Basidiomycota, and Zygomycota. About 10% of plant families have ectomycorrhizal relationships.
Ectomycorrhizas comprise a Hartig net of hyphae encircling the plant cells in the root cortex and a mantle or hyphal sheath covering the root tip. The term “ectendomycorrhiza” refers to a mycorrhiza in which the hyphae have the potential to enter the plant cells.
Springtails are attracted to and killed by the ectomycorrhizal fungus Laccaria bicolour to extract nitrogen, some of which may be passed to the mycorrhizal host plant.
Endomycorrhiza
Alternatively, endomycorrhizae are present in more than 80% of plant families, including greenhouse and crop plants such as vegetables, flowers, grasses, and fruit trees. The production of vesicles and arbuscules by the fungus and their penetration of the cortical cells are characteristics of endomycorrhizal relationships.
There are several types of endomycorrhizas including arbuscular, arbutoid, ericoid, monotropoid and orchid mycorrhizas.
Arbuscular Mycorrhiza
In an arbuscular mycorrhiza, also known as an AMF, the symbiotic fungus reaches the cortical cells of the roots of a vascular plant to produce arbuscules. Only members of the division Glomeromycota of fungi can produce arbuscular mycorrhizas.
Ericoid Mycorrhiza
Ericaceae plants and various mycorrhizal fungal lineages come together to produce the mutualistic association known as the ericoid mycorrhiza. It has also been demonstrated that ericoid mycorrhizas are highly saprotrophic, allowing plants to obtain nutrients from still-in-decomposition materials through the decomposing activities of their ericoid companions.
Monotropoid Mycorrhiza
This kind of mycorrhiza can be found in various genera of the Orchidaceae and the Ericaceae subfamily Monotropoideae. These plants get their carbon from the fungal companion and are heterotrophic or mixotrophic. Thus, this type of mycorrhizal relationship is parasitic and non-mutualistic.
Orchid Mycorrhiza
Every orchid undergoes myco-heterotrophic growth at some point in its life cycle, forming orchid mycorrhizas with various basidiomycete fungi. Their hyphae enter the root cells and create pelotons (coils) to exchange nutrients.
Uses & Benefits
Soil fungi called mycorrhizae provide the soil with numerous advantages. For a water-wise landscape, healthy soil is essential. The fertility and health of the soil and the plants that grow there are influenced by drainage, organic matter, and plant nutrients.
Mycorrhizae, meaning “fungus root,” refers to a mutualistic relationship between fungi and plant roots in most plants. While the fungus assists the plant by expanding its root surface area, the plant benefits the fungus by supplying the carbohydrates necessary for fungal growth.
Mycorrhizae may provide the following benefits:
- Increased absorption of nutrients and water
- Reduced need for irrigation
- Reduced demand for fertiliser
- Enhanced resistance to drought
- Improved resistance to pathogens
- Enhanced plant health and resistance to stress
- Improved transplant success
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