The Symbiotic Relationships of Fungus

By Iain MacLeod on Friday, May 5, 2006.

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As it turns out Mycorrhizal Fungi play a large role in helping other plants and trees grow.

As many as 90% of the world's plant species use beneficial fungi to acquire water and nutrients from the soil. The specialized roots that the plants grow and the fungus which inhabits them are together known as mycorrhizae, or "fungal roots". The famous, and delicious, truffle mushroom is a mycorrizal fungus.

Hi, this is Iain McLeod bringing you Something Wild.

A mycorrhizal fungus consists of a network of fine, underground, root-like filaments called hyphae which branch between soil particles and infiltrate decomposing organic matter. The hypae soak up water and nutrients over a large area, much larger than the plant can access on its own, and pass them on to the plant. In return, the plant provides the fungus with energy-rich sugars manufactured through photosynthesis. Mycorrhizal fungi can also protect plants against pathogenic fungi and micro-organisms.

Mycorrhizal fungi are very important for plant health. They are so beneficial, in fact, that agriculturists and botanists who work to reintroduce plants in conservation areas sometimes inoculate the soil with spores of these fungi to help plants grow.

In some cases, many orchids for example, the fungal partner is required for seed germination. In liverworts, mosses, ferns, conifers, and many flowering plants, fungi form a symbiotic, or mutually beneficial, relationship with the plant. Because mycorrhizal associations are found in so many plants, scientists believe they may have been an essential element in the transition of plants from water onto land.

Not all mycorrhizal relationships are so benevolent. Certain plants, such as Indian pipes survive without using chlorophyll. They share a mycorrhizal fungus with a nearby tree, and essentially parasitize the tree by way of the mycorrhizal fungus. And some orchid species never photosynthesize, but instead parasitize the mycorrhizal fungi.

So, whenever you?re admiring a blueberry bush, pine, oak or orchid - remember their unseen, but essential, fungal partners in the soil.

Something Wild is a joint production of New Hampshire Audubon, New Hampshire Public Radio, and the Society for the Protection of New Hampshire Forests.

For Something Wild, I?m Iain MacLeod.