haustorium

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (May 2007)

In botany, a haustorium (plural haustoria) is the hyphal tip of a parasitic fungus or of the root of a parasitic plant (such as in the broomrape family), that penetrates the host's tissue, but stays outside the host cell membrane.

Hyaloperonospora parasitica: Hyphae and haustoria

Fungi in all major divisions form haustoria. Haustoria take several forms. Generally, on penetration, the fungus increases the surface area in contact with host plasma membrane releasing enzymes that break down the cell wall, enabling greater potential movement of organic carbon from host to fungus.

Haustoria arise from intercellular hyphae, appressoria, or external hyphae. The hypha narrows as it passes through the wall of the cell and then expands on invaginating the cell. A thickened, electron-dense collar of material is deposited around the hypha at the point of invagination. Further, the host wall becomes highly modified in the invaginated zone. Inclusions normally present in plasma membrane are absent, and the outer layer contains more polysaccharide. The wall of both partners is severely reduced.

Functional exchange takes place within the haustorial complex. The host supplies organic carbon to the fungus, and the metabolic activity within the complex is considerably greater than outside. Carbon from the host is absorbed by the fungus, and immediately transported to the rest of the thallus. The host plant appears to be functioning according to signals from the fungus and the complex appears to be under the control of the invader.^[1]

The haustorium may be balloon-, spiral-, or glove-shaped.

Simpler Terms

Haustoria is basically a fungus that infects plants and small insects. In the insect's case (such as a grasshopper), it will expand inside of it and look as though it is "eating" the insect from the inside out. When it is finished it spores mushrooms out of the insect's carcass.

References

1. ^ Mycology - Structure and Function - Haustoria

This plant disease article is a stub. You can help Wikipedia by expanding it.