All about Mycorrhizae, its benefits, application and research and development
Mycorrhizae are considered to be a mutualistic relationship because both organisms benefit. The fungus receives the products of photosynthesis from the plant. Mycorrhizal fungi have existed since the first plants appeared on dry land more than million years ago. They form a close symbiotic relationship with plant. A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular host plant . Mycorrhizal fungi form a mutualistic relationship with the roots of most plant species. In return, the plant gains the benefits of the mycelium's higher absorptive capacity for water and mineral nutrients, partly because of the.
These organic components along with the growing medium they compose do not have mycorrhizal fungi strains that would benefit the crops grown in them, so they must be incorporated. This results in improved nutrient acquisition and uptake by plant roots, particularly elemental phosphorus Pzinc Znmanganese Mn and copper Cu and water.
In return, the plant provides carbohydrates for the fungi. There are more than species of mycorrhizal fungi found around the world in all types of soils and climates. There are several general classes to categorize mycorrhizal fungi; however, the two most common classes are called ectomycorrhiza and endomycorrhiza.
What is the Difference? Classification of mycorrhizal fungi is based on the inter-relation of the fungal hyphae and plant root cells.
Benefits of Mycorrhizae
Ectomycorrhiza form a compact mantel of hyphae on the outer surface of plant roots, but do not penetrate plant root cells.
However, hyphal strands penetrate the root surface and grow between cortical root cells and then extend outward from the mantle to soil surface.
Ectomycorrhiza commonly occur on pine Pinaceae and most other conifers, birch Betulaceaebeech and oak Fagaceae families and other woody plants. Due to their host range, ectomycorrhizae only provide benefits for forestry seedlings and woody ornamentals.
- WHAT ARE MYCORRHIZAE?
Endomycorrhizae form an association in which the hyphae penetrate and colonize epidermal and fleshy cortical cells of plant roots. Because of this, endomycorrhizae will be discussed in further detail. Endomycorrhizal Structures The most common type of endomycorrhizae is arbuscular endomycorrhizae. They are named based on the structures they produce, arbuscules and vesicles.
Two to three days after colonizing the cell, the hyphae form structures within plant cells called arbuscules Latin for tree which resemble tiny trees and serve to facilitate the transfer of nutrients within the cortical cells Figure 1. Spores have very thick walls, which makes them very resistant to freezing and intense heat so they can survive for long periods of time. The ability to form ectomycorrhizae is found in many families of fungi, but most commonly among members of the class Agaricomycotina of the Basidiomycota, especially those producing mushrooms and boletes.
Most of the larger mushrooms you see in the forest have arisen from the networks of extra-radicular hyphae permiating the soil beneath your feet. The abundance of these mushrooms, their sheer weight and volume, attests to the magnitude of their activities.
The energy and chemicals needed to build these mushrooms comes in great part from the trees, suggesting that the advantages a plant gains from mycorrhizae come at a cost. Most plants exclusively form arbuscular mycorrhizae but there are compelling reasons to focus attention on those having ectomycorrhizae as well.
Benefits of Mycorrhizae - eXtension
Although a smaller number of species are involved, ectomycorrhizae dominate in the pine, oak, birch, willow, walnut and several other families. In the tropics these include the dipterocarps and large woody legumes. In New Brunswick our extensive forests of spruce, fir, white pine, birch and poplar support immense continuous networks of ectomycorrhizal fungi.What are Mycorrhizal Fungi and How Do They Benefit Your Plants?
Without these fungi our forests as we know them would not exist. Thus the ecological and economic importance of ectomycorrhizae cannot be overestimated. Many biologists have noted the major differences between tropical and temperate forests and have attempted to relate these to dominance by certain mycorrhizal types. The pictures above illustrate two such forests; at left a tropical rain forest in northern Costa Rica and at right a forest near Schefferville, Quebec. The Costa Rican forest is dense and made up of a great variety of tree species.
You might walk some distance through this forest before encountering two individual trees of the same species.
Biodiversity here, including the trees, seems to be high. On the other hand the Quebec forest appears to have only one kind of tree. Mycorrhizal associations are seen in the fossil record and are believed to be one of the contributing factors that allowed early land plants, including Aglaophyton major one of the first land plantsto conquer the land.
Mycorrhizal fungi encompass many major groups of the fungus Kingdom and in the past were divided into two non-evolutionarily related groups: Ectomycorrhizal fungi ensheath the root cells but usually do not penetrate them extracellular.
Endomycorrhizal fungi penetrate and enter the cells of a plant root intracellular.
Modern research has lead to the recognition of seven types of mycorrhizal fungi, subdividing the old, traditional groups.
The new nomenclature is often more precise and specific to the associated plant taxa. The relatively homogenous ectomycorrhizal group largely remains with only the addition of the subgroup ectendomycorrhizas. The endomycorrhizal group has been dismantled, but specific types are now recognized: