Geosiphon pyriformis

from Wikipedia, the free encyclopedia
Geosiphon pyriformis
Geosiphon pyriformis by Wettstein.png

Geosiphon pyriformis

Systematics
Department : Glomeromycota
Class : Arbuscular mycorrhizal fungi (Glomeromycetes)
Order : Archaeosporales
Family : Geosiphonaceae
Genre : Geosiphon
Type : Geosiphon pyriformis
Scientific name of the  family
Geosiphonaceae
Engl. & E. Gilg
Scientific name of the  genus
Geosiphon
F.Wettst.
Scientific name of the  species
Geosiphon pyriformis
( Kütz. ) F. Wettst.
Nostoc blue-green algae in the cells of Geosiphon pyriformis

Geosiphon pyriformis is phylogenetically one of the arbuscular mycorrhizal fungi , even if no mycorrhizal symbiosis has been proven for it and forms the only species of the Geosiphonaceae family. It lives on loamy, nutrient-poor soils in symbiosis with certain strains of the blue-green alga Nostoc punctiforme .

Shape, meaning and distribution

The photosynthetically active symbiosis partner grows in about 1.5 mm long, dark, shiny vesicles of the otherwise microscopic fungus. It is the only known symbiosis in which cyanobacteria grow within the cells of a fungus. Cyanobacteria also live in a symbiosis with fungi in the form of lichens . Here, however, the cyanobacteria grow extracellularly without exception. So far, only a few finds for Geosiphon pyriformis have been documented. The localities are in Germany and Austria, with the Spessart being the main distribution area.

Function and origin of the symbiosis with Nostoc

Geosiphon pyriformis is an obligate symbiote, that is, it does not grow outside of the symbiosis. The cyanobacteria, on the other hand, are facultative symbiotic partners and can grow freely. Free living Nostoc strains are taken up by the hyphae of the fungus as threads from a few cells via endocytosis . The hyphae then grow into macroscopic bubbles in which the ingested cyanobacteria multiply and form heterocysts for N 2 fixation . Nostoc cells are only absorbed during a certain condition, the so-called primordium. This is the transition from the mobile expansion phase to the fixed form of life in the form of the gelatinous lumps of the typical Nostoc camp. The detection of this symbiosis-compatible phase is probably based on a lectin -mediated process. The fungus receives the photosynthetically formed sugars from the cyanobacteria and possibly nitrogen compounds from the heterocysts. For Nostoc , the advantage of the symbiosis is a sufficient supply of water, phosphate and CO 2 for growth and photosynthesis .

Symbiosis as an argument for the endosymbiotic theory

The mushroom is considered to be a witness to the early tribal history of plants. The endosymbiotic theory can be understood and experimentally developed on it, because it absorbs free-living cyanobacteria and uses them for its own metabolism. According to the endosymbiont theory, the chloroplasts developed from a comparable "domestication" of cyanobacteria.

Symbiosis with other organisms

Geosiphon pyriformis lives in symbiosis with other organisms at the same time: On the one hand, another bacterial but previously unidentified endosymbiont is found, which occurs in many other arbuscular mycorrhizal fungi. On the other hand, the fungus always grows in the company of hornworts ( Anthoceros and Phaeoceros ) and the liverwort Blasia pusilla . The fungal hyphae are associated with the thalli and rhizoids of the accompanying moss plants, which also live in symbiosis with Nostoc . The Nostoc strains grow extracellularly in these mosses and are compatible with Geosiphon pyriformis .

credentials

  1. ↑ Heribert Schöller: Lichen - history, biology, systematics, ecology, nature conservation and cultural significance . Schweizerbartsche Verlagsbuchhandlung, Frankfurt am Main 1997, ISBN 3-7829-1151-2 , pp. 21-28
  2. ^ Mycobank, accessed December 15, 2011
  3. ↑ A. Schüßler, M. Kluge: Geosiphon pyriformis, an endocytosymbiosis between fungus and cyanobacteria, and its meaning as a model system for arbuscular mycorrhizal research. In: B. Hock (ed.), The Mycota IX. 2001. Springer Verlag, Berlin Heidelberg New York, pp. 151-161
  4. ↑ Schüßler, A., Meyer, T., Gehrig, H., and Kluge, M., 1997: Variations of lectin binding sites in extracellular glycoconjugates during the life cycle of Nostoc punctiforme, a potentially endosymbiotic cyanobacterium . Eur. J. Phycol., Vol. 32, pp. 233-239
  5. ↑ cf. Manfred Kluge, Dieter Mollenhauer , Resi Mollenhauer Geosiphon pyriforme (Kützing) von Wettstein, a Promising System for Studying Endocyanoses Progress in Botany 55 (1994): 130-141
  6. ↑ Archive link ( Memento of the original from August 5, 2012 in the web archive archive.today ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.lrz-muenchen.de
  7. ↑ Heribert Schöller: Lichen - history, biology, systematics, ecology, nature conservation and cultural significance . Schweizerbartsche Verlagsbuchhandlung, Frankfurt am Main 1997, ISBN 3-7829-1151-2 , pp. 21-28

Web links