Mycorrhiza - Wikipedia
Mycorrhizas are symbiotic relationships between fungi and plant roots (the term . The fungus takes over the normal nutrient-absorbing role of the root hairs. Mycorrizal fungi help plant roots absorb nutrients and fight off harmful predators. Mycorrhizal Fungi and Plant Roots: A Symbiotic Relationship Observations of hyphae bound together with root hairs weren't reported until the 19th century. Rhizobia and the mycorrhizal fungi live with plants in symbiotic relationships. beyond the length of roots, and allow the roots to absorb more nutrients than they would without The Rhizobium docks to the root hair tip to begin the symbiosis.
They have a simple intraradical grow in cells phase, consisting of dense coils of hyphae in the outermost layer of root cells. There is no periradical phase and the extraradical phase consists of sparse hyphae that don't extend very far into the surrounding soil.
They might form sporocarps probably in the form of small cupsbut their reproductive biology is little understood. It is however different from ericoid mycorrhiza and resembles ectomycorrhiza, both functionally and in terms of the fungi involved.
Myco-heterotrophy This type of mycorrhiza occurs in the subfamily Monotropoideae of the Ericaceaeas well as several genera in the Orchidaceae.
These plants are heterotrophic or mixotrophic and derive their carbon from the fungus partner.
Nutrient Acquisition by Plants | Biology
This is thus a non-mutualistic, parasitic type of mycorrhizal symbiosis. Orchid mycorrhiza All orchids are myco-heterotrophic at some stage during their lifecycle and form orchid mycorrhizas with a range of basidiomycete fungi. In such a relationship, both the plants themselves and those parts of the roots that host the fungi, are said to be mycorrhizal.
The Orchidaceae are notorious as a family in which the absence of the correct mycorrhizae is fatal even to germinating seeds. This relationship was noted when mycorrhizal fungi were unexpectedly found to be hoarding nitrogen from plant roots in times of nitrogen scarcity.
Researchers argue that some mycorrhizae distribute nutrients based upon the environment with surrounding plants and other mycorrhizae. They go on to explain how this updated model could explain why mycorrhizae do not alleviate plant nitrogen limitation, and why plants can switch abruptly from a mixed strategy with both mycorrhizal and nonmycorrhizal roots to a purely mycorrhizal strategy as soil nitrogen availability declines.
On the right side of this diagram, the arbuscular mycorrhiza pathway, which branches off from the plant root, which is the brown cylinder-like figure in the image, provides the plant with nutrients, including, most importantly, phosphate and nitrogen. My reference source for this information is: In return, the plant gains the benefits of the mycelium 's higher absorptive capacity for water and mineral nutrients, partly because of the large surface area of fungal hyphae, which are much longer and finer than plant root hairsand partly because some such fungi can mobilize soil minerals unavailable to the plants' roots.
The effect is thus to improve the plant's mineral absorption capabilities. One form of such immobilization occurs in soil with high clay content, or soils with a strongly basic pH.
Mycorrhizae allow plants to live in desolate areas that are poor in nutrientssuch as road-sides, disturbed soil near mining operations and in tropical rain forests.
Surprisingly, rain forests are often depleted of nutrients because there is so much competition by other plants for nutrients. In these nutrient-poor soils mycorrhizae can help plants to live where they otherwise might die. These are called "endomycorrhizae," Endo means inside.
DLC-ME | The Microbe Zoo | Dirtland | Root Cellar
Many of these endomycorrhizae form tiny trees and little sacs inside root cells. These tiny trees, called "arbuscules" Latin for tree and tiny sacs, called "vesicles" little sac are connected to long threads of the mycorrhizae that lead out into the soil.
These long threads, called hyphae, are analogous to the roots of plants. These hyphae extend beyond the length of roots, and allow the roots to absorb more nutrients than they would without the help of the fungus. These fungi have a thick network of thin, fungal cells, or hyphae, that cover the roots of the plants.
- Mycorrhizal Fungi and Plant Roots: A Symbiotic Relationship
- The Root Cellar
- Nutrient Acquisition by Plants
This covering protects the roots in a sheathe of ectomycorrhizal cells. These fungi are friends mostly with pine trees. Often, deforested lands are planted with tree seeds, together with mycorrhizal fungi, which help seedlings get a good start in life.