Question

Contrast endomycorrhizae vs. ectomycorrhizae. Where and how does each colonize plant roots? Which is more common in plant roots

Answer 1

Mycorrhizae is the symbiotic association between fungus and higher plant roots. Name itself refers the connection. As fungus gets a host to retain and the protection of a shelter, higher plants get phosphorous and nitrogen from soil through the action of this fungus. These mycorrhiza also increases the surface area of roots. This relation can be solely divided into endo and ecto mycorrhizae.

Endomycorrhizae: The condition where the fungal hyphae actually penetrate into the cellwall and invaginate inside the cell membrane.

Ectomycorrhizae: Fungi actually grows outside the roots. These hyphae can form mycelium which interconnects to form a web. Thus fungi growing in different plants can get connected and nutrients are thus shared.

Where and how they colonize?

Ectomycorrhizae: They colonize in the root surface without any penetration. They are much smaller and thin fibre like structure which are commonly seen as colonies. Individual separation is difficult. They are mainly seen in coniferous tree roots. However their anchorage occurs by penetration of some extend to the cotical cells and then penetrate back into the outside.

Endomycorrhizae: They are characterized by arbuscules and vesicles. They produce enzymes which allow them to penetrate through epidermis and fleshy cortex. In course of time these hyphaes reinside between cortical cells to form arbuscules. They supply nutrients and water to the neighbouring cells and in return fungus get carbohydrates.

Vesicles are sac like structures seen in the terminal end of hyphae inside the cell which acts as a storage organ of fungus for lipids . They also act as a propagule which can propogate into new fungi.

It take 6 weeks for an endomycorrhizae to completely colonize inside a plant root cell.

The most common among them is endomycorrhizae. 85% of the higher plants contain arbuscular mycorrhiae.