What are Mycorrhizae?

摘要

Mycorrhizae (mycorrhizae = "fungus-roots") (pronounced like Mike O'Rhizee) are symbioses between plant roots and specialized fungi that help the plant absorb nutrients and moisture from the soil and provide an energy source (carbon) for the fungus. There are two main types, and they are distinguished by whether the threads that make up the mycelium (hyphae) are external to root cells (ectomycorrhizae, EcM) or internal to root cells (endomycorrhizae). Ectomycorrhizae are by far the most common mycorrhizae on woody plants that we've studied, a trend that seems characteristic of northern latitudes. EcM have a Hartig net between root cells and a sheath enveloping the root tip (Fig. 1), and external hyphae (Figs. 2-3, cover photo) that allow the fungus to access much larger volumes of soil than that available to the plant roots alone (Read 1992; Smith and Read 1997). Endomycorrhizae have hyphae internal to root cells and have several subdivisions including arbuscular, ericoid, arbutoid, and other types.