Conidia
Conidia (syn. Konidiosporen , Akrosporen , conidia ) is called a particular form of spores of the fungus , but also by prokaryotes the genus Streptomyces . In fungi, they are counted among the mitospores and are consequently formed asexually ( mitotic ) outside the sporangium through the transformation of hyphae or on conidia carriers. They are the organs of distribution of vegetative reproduction characteristic of the higher fungi ( Asco and Basidiomycetes ). In the genus Streptomyces , which belong to the gram-positive bacteria, they are generated by the simple formation of transverse walls in the multinucleated sporophore .
Single or multi-cell, as well as simple or complex shapes are possible. Conidia can also have a smooth or structured surface, small or large, colorless or intensely colored.
Conidia are formed by many skin fungi ( dermatophytes ). In medical mycology, a distinction is made between unicellular microconidia and multicellular macroconidia .
For example, conidia occur in apple scab in summer and play a central role as the cause of many plant diseases.
Some noble molds that are used in the cheese dairy also belong to the conidia-forming molds , e.g. B. Penicillium camemberti and Penicillium candidum .
Types
Depending on the formation of the conidia, different types are distinguished:
- Aleurispores are formed from the distended end of a hypha or a lateral distension and separated by septa.
- Arthrospores or oidia are formed by dividing existing hyphae by septa and then transforming the individual segments into spores.
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Blastospores form as protuberances on hyphae tips or other positions and mature from the base. They separate without the formation of septa . If blastospores are formed on minor axes, they are called sympodiospores . In addition, there are a number of spore types which, depending on the author, are regarded as special cases of the blastospore or as a separate type:
- Porospores are thick-walled and are formed individually or in whorls by pores in the cell wall of the spore-bearing hyphae and can also be formed as chains growing from the base to the tip.
- Radula spores are formed next to each other on small teeth that stand like a comb at the tip of the spore-bearing hyphae.
- Clamydospores are the thick-walled permanent spores that arise intercalary (limited to certain zones) or through swelling of hyphae ends. Furthermore, it is an outdated name for the teleutospores (burn spores) of the Ustomycetes.
Conidia fruit form
The asexual reproductive stage of a fungus that has arisen from such conidia is called conidia (fruit) form, conidial stage or also minor fruit form, imperfect form or anamorphic . These imperfect fruit bodies have a different external shape than the perfect or main fruit form or teleomorphs germinated from sexual spores (= Asco- or Basidiosporen) . The conidial stage is usually classified separately from the sexual stage on a morphological basis, so that both forms have different names in scientific nomenclature. (Example: the red pustel mushroom is called Nectria cinnabarina in the perfect stage , while the imperfect form is called Tubercularia vulgaris .) This different name is based on a time when the morphologically different teleo- and anamorphic fruiting bodies of one and the same fungus are not yet known as could see one and the same species. Nowadays it is often possible to use genetic and molecular biological methods to determine the relationship between these outwardly different forms of development. Both forms can occur side by side, but the conidial stage is often the most common in nature. Some mushrooms even reproduce exclusively asexually, so that no main fruit form is known of them. Historically, it was called Deuteromycetes or Fungi imperfecti.
Conidiomata
Conidiomata (Singular: Conidioma; also: Konidioma) are in certain fungi ( Coelomycetes , an anamorphic class of Deuteromycotina) fruit-body-like structures in which conidia formation takes place. These structures are clearly delimited from the mycelium by a clearly differentiated fruiting body wall. In them are the conidiogenic cells, i.e. H. Cells from or on which the conidia arise in an asexual way. Conidiomata thus correspond in principle to the fruiting bodies of the Asco- and Basidiomycetes. H. O. Schwantes suggests that such structures should not be grouped under the term fruiting bodies - this should be reserved for the ascocarps and basidiocarps, i.e. teleomorphic fruiting bodies - but rather be called fructifications .
literature
- Thomas D. Brock (first), Michael T. Madigan, Jack Parker: Microbiology . 9th edition. Spectrum, Akademischer Verlag, Heidelberg et al. 2001, ISBN 3-8274-0566-1 .
- Emil Müller, Wolfgang Loeffler: Mycology. Floor plan for scientists and physicians. 5th revised edition. Thieme, Stuttgart et al. 1992, ISBN 3-13-436805-6 .
- Hans Otto Schwantes: Biology of the mushrooms. An introduction to applied mycology (= university paperbacks . Volume 1871 ). Ulmer, Stuttgart 1996, ISBN 3-8252-1871-6 .
- ^ MK Dasgupta: Principles of plant pathology . Allied Publishers, New Delhi 1988, ISBN 81-7023-192-2 , pp. 80 .
- ↑ Hanns Kreisel: The genera of the large mushrooms in Europe. Identification key and complete index of volumes 1 to 5 (= manual for mushroom friends . Volume 6 ). 2nd, revised and expanded edition. Fischer, Jena 1988, ISBN 3-437-30352-X .
- ↑ Heinrich Dörfelt , Gottfried Jetschke (Ed.): Dictionary of Mycology. 2nd Edition. Spectrum, Akademischer Verlag, Heidelberg et al. 2001, ISBN 3-8274-0920-9 .
- ↑ Heinrich Dörfelt (ed.): Lexicon of mycology. G. Fischer, Stuttgart et al. 1989, ISBN 3-437-20413-0 , p. 100.
- ↑ Müller, Loeffler: Mykologie. 1992.
- ↑ See: Schwantes: Biology of Fungi. 1996, p. 84 ff.