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Mycorrhiza (pronounced Mike ORyza) is the name of the very important relationship between plant roots and certain types of fungi. Unlike the fungi that cause diseases, the mycorrhizal relationship benefits both the host plant and the fungi. The plant provides the fungi with carbohydrates and, in exchange, the fungi increase the plants ability to take up phosphorus and micronutrients from the soil and provide protection from certain root diseases. It also improves the plants ability to access water from the surrounding soil, which helps keep the plant hydrated in dry soil conditions.
There are two main types of mycorrhizal relationships:
ectomycorrhizae and arbuscular mycorrhizae. The ectomycorrhizae (ECM) fungi physically connect with the roots of the host plant, improving the plants ability to take up water and nutrients. They also form a sheath, or mantle, around the root, which physically protects the root from some types of disease-causing fungi.
Arbuscular mycorrhizae (AM) the main difference between the AM and ECM relationship is that the AM relationship does not create a protective mantle around the root the way the ECM does. Instead, its hyphae enter the plant cells, producing structures that facilitate water and nutrient uptake by the plant. One way to spread AM fungi is to collect root tissue and the soil immediately surrounding the root from a host plant that is known to have the AM fungi and incorporate it into the soil of the new plant. Management of arbuscular mycorrhizae focuses on maintaining soil conditions favoring the fungi rather than constantly adding more fungicolonized tissue to the host plant.
What are the benefits of the mycorrhizal relationship to the plant?
Increased absorption of nutrients and water: Plants absorb nutrients and water through their fine root hairs; the mycorrhizal relationship increases the amount of nutrients and water the plant can absorb by providing fungal hyphae, which function in a similar way. The fungal hyphae, however, have three advantages over the plants root hairs: 1) the hyphae reach farther out into the soil, covering more area than the root hairs, 2) they are more attracted to nutrients than root hairs, and 3) they are smaller than root hairs, so they can get into spaces in the soil that the root hairs cannot. Researchers have measured between 7 and 8 miles of mycorrhizal hyphae in about a teaspoon of soil; these hyphae increase the amount of soil the plant can access by up to 100,000 times.
Increased phosphorus uptake: Hyphae promote the growth of bacteria that can extract phosphorus from organic matter. The phosphorous released by the bacteria is absorbed by hyphae and passed on to the plant. This is the most well-known nutrient benefit, but the hyphae also increase the plants uptake of potassium, copper, iron, nickel, sulfur and zinc.
Root disease suppression: Mycorrhizal relationships protect host plants from disease both
chemically and physically. The fungi produce antibiotics that inhibit disease organisms and
further suppress diseases by improving host nutrition, which increases plant vigor. Healthy
plants are better able to resist or tolerate pathogens such as Fusarium, Rhizoctonia, Phythium
and Phytophthora (all root-rots) and Verticillum (a stem disorder). Also, the protective sheath, or mantle, formed by the ECM relationship physically protects the root from disease.
Increased production of plant growth hormones:
Mycorrhizal colonization often increases levels of cytokinins and gibberellins, which are plant hormones responsible for cell division, stem elongation, seed germination and other functions.
Enhanced the soils physical characteristics:
Compounds like glomalin, a carbohydrate/protein molecule, are excreted by fungal hyphae
and act like glue, causing soil particles to stick together, or aggregate. Soil aggregates are resistant to breakdown by water and enhance the soils physical characteristics, such as water and air movement in the soil. The fungal hyphae also physically hold nonaggregated soil particles together, allowing other bacterial and fungal compounds to form these particles into aggregates. These aggregates are important for the soil food web.
http://www.uaf.edu/files/ces/publications-db/catalog/anr/HGA-00026.pdf
There are two main types of mycorrhizal relationships:
ectomycorrhizae and arbuscular mycorrhizae. The ectomycorrhizae (ECM) fungi physically connect with the roots of the host plant, improving the plants ability to take up water and nutrients. They also form a sheath, or mantle, around the root, which physically protects the root from some types of disease-causing fungi.
Arbuscular mycorrhizae (AM) the main difference between the AM and ECM relationship is that the AM relationship does not create a protective mantle around the root the way the ECM does. Instead, its hyphae enter the plant cells, producing structures that facilitate water and nutrient uptake by the plant. One way to spread AM fungi is to collect root tissue and the soil immediately surrounding the root from a host plant that is known to have the AM fungi and incorporate it into the soil of the new plant. Management of arbuscular mycorrhizae focuses on maintaining soil conditions favoring the fungi rather than constantly adding more fungicolonized tissue to the host plant.
What are the benefits of the mycorrhizal relationship to the plant?
Increased absorption of nutrients and water: Plants absorb nutrients and water through their fine root hairs; the mycorrhizal relationship increases the amount of nutrients and water the plant can absorb by providing fungal hyphae, which function in a similar way. The fungal hyphae, however, have three advantages over the plants root hairs: 1) the hyphae reach farther out into the soil, covering more area than the root hairs, 2) they are more attracted to nutrients than root hairs, and 3) they are smaller than root hairs, so they can get into spaces in the soil that the root hairs cannot. Researchers have measured between 7 and 8 miles of mycorrhizal hyphae in about a teaspoon of soil; these hyphae increase the amount of soil the plant can access by up to 100,000 times.
Increased phosphorus uptake: Hyphae promote the growth of bacteria that can extract phosphorus from organic matter. The phosphorous released by the bacteria is absorbed by hyphae and passed on to the plant. This is the most well-known nutrient benefit, but the hyphae also increase the plants uptake of potassium, copper, iron, nickel, sulfur and zinc.
Root disease suppression: Mycorrhizal relationships protect host plants from disease both
chemically and physically. The fungi produce antibiotics that inhibit disease organisms and
further suppress diseases by improving host nutrition, which increases plant vigor. Healthy
plants are better able to resist or tolerate pathogens such as Fusarium, Rhizoctonia, Phythium
and Phytophthora (all root-rots) and Verticillum (a stem disorder). Also, the protective sheath, or mantle, formed by the ECM relationship physically protects the root from disease.
Increased production of plant growth hormones:
Mycorrhizal colonization often increases levels of cytokinins and gibberellins, which are plant hormones responsible for cell division, stem elongation, seed germination and other functions.
Enhanced the soils physical characteristics:
Compounds like glomalin, a carbohydrate/protein molecule, are excreted by fungal hyphae
and act like glue, causing soil particles to stick together, or aggregate. Soil aggregates are resistant to breakdown by water and enhance the soils physical characteristics, such as water and air movement in the soil. The fungal hyphae also physically hold nonaggregated soil particles together, allowing other bacterial and fungal compounds to form these particles into aggregates. These aggregates are important for the soil food web.
http://www.uaf.edu/files/ces/publications-db/catalog/anr/HGA-00026.pdf