Chlamydospore
A chlamydospore (from the Greek χλαμύς chlamys , "coat") is an asexually formed fungal spore through mitosis , which serves to survive the organism rather than its spread. It is characterized by particularly thick cell walls and a regular, mostly spherical shape. Chlamydospores can survive long periods without a supply of nutrients without losing their ability to germinate. Since they are formed asexually, they are often subsumed under the term conidia . Gems fulfill a similar function as chlamydospores , but they do not have a regular shape. Since the terms are often used synonymously, it is often not possible to clearly differentiate between them in the literature.
Origin and structure
Chlamydospores in the narrower sense are formed by a transformation of hyphae cells . The cytoplasm first condenses in places and surrounds itself with a regular cell wall, which is usually thick and pigmented. The cell wall of the hyphae cell is retained and forms the additional, eponymous coat of the spore. The chlamydospore is not separated from the mycelium , but remains connected to the adjacent hyphae cells. The chlamydospore is only released when the surrounding cells dry out, die off or are dissolved . When the external circumstances allow growth again, the chlamydospore germinates into a new mycelium.
Definition of terms
The term chlamydospore refers to both the function of persistence and the shape of the spore. Unlike conidia, they are not primarily used for spreading. In contrast to gems , chlamydospores are formed regularly and have a more or less uniform, spherical shape. Some mycologists often subsume chlamydospores under conidia or equate them with gems, which makes a precise definition more difficult. Occasionally aleuriospores , which have a different release mechanism and mostly serve to spread, are also referred to as chlamydospores.
Classification
Depending on their formation, chlamydospores are divided into three different categories:
- Terminal chlamydospores are formed in the end segment of a hyphal thread.
- Intercalary chlamydospores are formed in intermediate segments of a hyphal thread. They can often not be clearly differentiated from gems.
- Sessile (stalked) chlamydospores are formed in stem-like outgrowths of a hyphae thread.
source
literature
- Heinrich Dörfelt , Gottfried Jetschke (Ed.): Dictionary of mycology . 2nd Edition. Spectrum, Academic Publishing House, Heidelberg a. a. 2001, ISBN 3-8274-0920-9 .