Not many people know about mycorrhizal fungi, so I'm here to teach you all the benefits so you can have a healthier garden!

What is Mycorrhizal Fungi and how does it work?

The plant gives carbohydrates (products of photosynthesis)
to the fungus, while the fungus gives the plant water and
minerals in exchange. Link

Mycorrhizal fungi is a symbiotic relationship between fungi and a plant. Mycorrhizal fungi penetrates the plants roots and colonizes them. The fungi acts as an extension to the plants roots, as it absorbs water and nutrients that is far beyond the roots reach, and transports it along the mycorrhizal fungi network to the root zone of the plant. The plant then absorbs the water and nutrients from the mycorrhizal fungi, and in return gives the mycorrhizal fungi carbohydrates.

All that is needed to start this symbiotic relationship is a single fungi spore. Once a spore comes in contact with a plants roots, the spore germinates and forms mycelium (Mycelium is the vegetative part of a fungus or fungus-like bacterial colony, consisting of a mass of branching, thread-like hyphae). The mycelium then must penetrate the roots and if successful, a symbiotic relationship forms.


Types of Mycorrhizae Fungi

Even though there are seven types of mycorrhizae that have been discovered so far, the two types that are most commonly found are ectomycorrhizae and endomycorrhizae. Ectomycorrhizae fungi only externally associated with the plant root. This means the ectomycorrhizae hyphae does not penetrate the plants root cells, only the roots themselves. Ectomycorrhizae fungi mainly colonizes plants like trees and shrubs, and is less common than endomycorrhizae fungi. 

On the other hand, endomycorrhizae fungi form their associations within the cells of the host. This means the endomycorrhizae hyphae does penetrate the plants root cells. Endomycorrhizae colonizes all plants but woody trees and shrubs. These include everything from weeds, flowers, bulbs, berry bushes, grasses, and more. Interestingly enough, there are some plant species that mycorrhizal fungi cannot colonize. Plants in the Brassicaceae family, which include plants like broccoli, turnip, cabbage, collard greens, cauliflower, etc., cannot be colonized by mycorrhizal fungi.


Benefits of Mycorrhizal Fungi

The hyphal network of arbuscular mycorrhizal fungi (AMF) extends beyond the depletion zone (grey), accessing a greater area of soil for phosphate uptake. A mycorrhizal-phosphate depletion zone will also eventually form around AM hyphae (purple). Other nutrients that have enhanced assimilation in AM-roots include nitrogen (ammonium) and zinc. Benefits from colonization include tolerances to many abiotic and biotic stresses through induction of systemic acquired resistance. Link











There are four main benefits of mycorrhizal fungi that researchers have discovered so far. The first is more efficient water and nutrient uptake. Mycorrhizal fungi are naturally more efficient at absorbing water and nutrients in soils than plant roots. As well, the distance and size that plant roots can branch out is limited. When mycorrhizal fungi connect to a plants roots, they grow and expand past the plants roots limit and search for nutrients. This basically doubles the surface area that the plants roots would have been able to cover alone.

The second benefit of mycorrhizal fungi is altered root morphology and physiology. Researchers have observed that mycorrhizal fungi produce growth hormones and growth regulators when in a symbiotic relationship with a plant. They observed that roots that mycorrhizal fungi have colonized are healthier, bigger, and more fibrous. These hormones and regulators are responsible for the altered metabolism and growth of the roots compared to plants roots that are not in a symbiotic relationship with mycorrhizal fungi.

Link
The third benefit of mycorrhizal fungi is the detoxification of soils and the ability for plants to grow in nutrient-poor soils. Researchers proved this theory in a study by planting a variety of tree seedlings at abandoned mine sites where soils were too toxic to support growth and vegetation, where half of the seedlings receiving mycorrhizal fungi, and the other half did not. Researchers found that the seedlings that received mycorrhizal fungi survived and grew, but grew at slightly below average rates, while the trees that did not received mycorrhizal fungi died. When completing a soil sample after the trees were planted, the researchers discovered that the toxicity in the soil had decreased. 

The fourth and last benefit of mycorrhizal fungi is better protection against pathogens and diseases. Researchers found that plants that have been colonized by mycorrhizal fungi had better resistant to pathogens and diseases, compared to plants that had not been colonized by mycorrhizal fungi. The researchers theorize that the colonized plants had better protection because either mycorrhizal fungi produce antibiotics which fight and stop potential root pathogens, the mycorrhizal fungi acts as a physical barrier between the pathogens and diseases and the plants roots, the mycorrhizal fungi causes the plant to produce chemical inhibitors, the mycorrhizal fungi causes differences in the speed and rate of discharge of chemicals from the roots, or the mycorrhizal fungi helps establish protective microbial populations around the roots.


References for this Post

http://admin.ipps.org/uploads/50_145.pdf

http://admin.ipps.org/uploads/45_15.pdf

http://admin.ipps.org/uploads/48_29.pdf

http://admin.ipps.org/uploads/24_19.pdf

http://admin.ipps.org/uploads/58_128.pdf