Arbuscular mycorrhiza

Gigaspora margarita

The arbuscular mycorrhizal fungi ( Glomeromycetes ) or short- AM fungi ( arbuscular mycorrhizal fungi english, AMF) are the most common and oldest mycorrhizal fungi. Spreads are still the names of VAM fungi or VA. More than 80 % of all land plants go a symbiotic relationship one with these fungi. For example, the grasses ( Poaceae ) as most herbaceous plants by AM fungi depends. Also, most woody plants ( seen worldwide) live in symbiosis with AM fungi.

Until recently introduced the AM fungi to the Jochpilzen ( Zygomycota ). Genetic studies showed that they form a completely separate division Glomeromycota and not just " imperfect " Jochpilze are.

Well-known genera of Glomeromycota Glomus and Gigaspora are for example. The largest spores of Glomeromycota are nearly 1 mm in size, the smallest only about 40 microns. Some species sometimes form fruiting bodies, can have up to 3 centimeters in diameter ( hypogeous fruiting bodies ) and spore clusters or Sporokarpe represent.

  • 3.1 demarcation

Evolution

The formation of arbuscular mycorrhiza by Glomeromycota can be dated back to the era of the Ordovician, as the first moss-like plants began to colonize the mainland of the earth. There are probably AM fungi since 900 or even 1,200 million years, so they are already much older than terrestrial plants. As cyanobacteria symbiotic partner then came into question. This possibility is supported by the current existence of a symbiosis of Glomeromycota ( Geosiphon pyriformis ) with cyanobacteria ( Nostoc ), which is the only known endosymbiosis of a fungus with cyanobacteria.

Mark

Because the hyphae of the fungi penetrate the cortical cells of plant roots, one speaks of a Endomycorrhiza (Greek endo = inside). The tree-like hyphal structures formed by the fungi within the root cortex cells are characteristic of the Glomeromycota and hot ( after the Latin word for tree arbusculum ) arbuscules. To the root is formed around a loose but dense network of hyphens, there chlamydospores can form in the interest of asexual reproduction. The root hair formation is not suppressed.

Unlike other mycorrhizal fungi

A largely external sheath of the root by the fungus to penetrate the intercellular between the highest root cells of the plant tissue is called ectomycorrhizal ( gr ecto = outside). It is the most widespread mycorrhizae of most forest trees of temperate climate zones ( most tropical trees form AM). In the endomycorrhizal hyphae of the fungus penetrate the root cells. In addition, there are other forms of mycorrhiza as adaptation to extreme habitats: ericoid mycorrhiza, mycorrhiza Monotropoide, Orchideenmykorrhiza, Ektendomykorrhiza and Arbutoide mycorrhiza. However, these are all trained not obligate symbiotic Glomeromycota (AM fungi ).

System

After AMF phylogeny (LMU Munich), the Glomeromycota are systematized follow the order structure was also in the classification by Hibbet et al. 2007 Covered:

Kingdom: Fungi (Fungi )

Department: AM fungi ( Glomeromycota )

Class: Glomeromycetes

  • Order: Jochtrüffelartige ( Glomerales ) Family: Jochtrüffelverwandte ( Glomeraceae ) (at least 1 other family) Genus: Glomus (at least 3 other genera )
  • Family: Acaulosporaceae Genus: Acaulospora
  • Genus: Kuklospora
  • Genus: Entrophospora
  • Genus: Diversispora (at least 1 other with ' Glomus ' types )
  • Genus: Gigaspora
  • Genus: Scutellospora
  • Genus: Pacispora
  • Family: Archaeosporaceae Genus: Archaeospora
  • Genus: Intraspora
  • Genus: Ambispora
  • Genus: Geosiphon
  • Family: Paraglomeraceae Genus: Paraglomus

As can be seen easily, the previous, largely building on a molecular phylogeny, systematics something temporary still clings. The genus Glomus is still polyphyletic, meaning they did not emerge from a common ancestor. Another change in the system due to recent genbasierender studies is to be expected.

Demarcation

The earlier asked to Jochtrüffelartigen genus Endogone ( a typical representative of Jochpilze ) has nothing to do with the Glomeromycota respectively the Glomeromycetes respectively the Glomerales.

Organism Opisthokont Glomus (fungus) Diversisporales Archaeosporales
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