Ever since first learning about mycorrhizal fungi in my Ecology class in Spring Semester 2018 I have been utterly fascinated with them. The mycorrhizal fungus (this site has the basic information on fungus that allowed me to feel confident about writing this post) forms a mutualistic relationship with a terrestrial plant via the roots. The relationship is called a mycorrhiza. A mycorrhiza is formed when the hyphae of the mycorrhizal fungus is in contact with the roots of a land plant. Hypothesized in an article by the Centre for Australian National Biodiversity Research, 80-90% of land plants form mycorrhiza.
The plant receives-
*increased water absorption
*access to previously inaccessible (insoluble compounds) nutrients (such as elemental Phosphorus, Zinc, Manganese, and Copper)
*increased protection against some pathogens
The mycorrhizal fungi receives-
*carbohydrates formed from photosynthesis (photosynthate)
Ectomycorrhizal fungi form a complex of hyphae around the epidermis of the plant roots, but do not penetrate the root cells. Hyphal strands, from the hyphae, do enter the root cells. The hyphae covering is described as “net-like” and is called a Hartig Net. The Hartig Net acts as the site of nutrient exchange between the plant and the fungus, but it also limits root growth. This keeps the plant dependent on the fungus.
Ectomycorrhiza are typically found with pine (Pinaceae) and most other conifers, birch (Betulaceae), beech and oak (Fagaceae) families and other woody plants (Mycorrhizae: Description of Types, Benefits and Uses).
Endomycorrhizal fungi associate with the plant roots by penetrating the root epidermis with their hyphae. The main body of the fungus is found in the plant root, the fungus then extends individual hyphae. hyphal strands out into the soil creating a hyphal network around the root.
“Endomycorrhizae can occur on most seed bearing plants (except those colonized by ectomycorrhizae), rain-forest tree species, most agriculture crops and a vast variety of ornamental greenhouse crops. In fact, about 85 percent of the plant families in the world are colonized by endomycorrhizae”(Mycorrhizae: Description of Types, Benefits and Uses).
Mycorrhizal fungi often form associations with multiple host individuals. These can be individuals of the same species, or different species. Either way these individuals become connected. Mycorrhizal fungi can use this connection to funnel resources from one individual to another or to relay communication. The mycorrhizae can funnel nutrients from a healthy individual to one that is struggling or completely cut of the straggler and let it die. In some cases the mycorrhizal fungi use the photosynthate from a plant to feed an achlorophyllous plant that the fungus gets other resources from.
There is so much more to learn with Mycorrhiza, and that is why it blows my dang mind.