Frankia

Frankia
An alder root nodule.
Scientific classification
Domain:Bacteria
Phylum:Actinobacteria
Class:Actinobacteria
Order:Frankiales
Family:Frankiaceae
Genus:Frankia
Brunchorst, 1886[1]
Species
  • F. alni (Woronin 1866) Von Tubeuf 1895
  • F. asymbiotica
  • Ca. F. californiensis
  • F. casuarinae
  • F. coriariae
  • Ca. F. datiscae Persson et al. 2011
  • F. discariae
  • F. elaeagni
  • F. inefficax
Synonyms

Frankiella Maire and Tison 1909

Frankia is a genus of nitrogen-fixing, filamentous bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae. Bacteria of this genus also form root nodules.

This genus was originally named by Jørgen Brunchorst in 1886 to honor the German biologist, Albert Bernhard Frank.[2] Brunchorst considered the organism he had identified to be a filamentous fungus. Becking redefined the genus in 1970 as containing prokaryotic actinomycetes and created the family Frankiaceae within the Actinomycetales. He retained the original name of Frankia for the genus.[3]

A section through an alder root nodule

Overview

Frankia alni is the only named species in this genus, but a great many strains are specific to different plant species. The bacteria are filamentous and convert atmospheric nitrogen into ammonia via the enzyme nitrogenase, a process known as nitrogen fixation. They do this while living in root nodules on actinorhizal plants. The bacteria can supply most or all of the nitrogen requirements of the host plant. As a result, actinorhizal plants colonise and often thrive in soils that are low in plant nutrients.[4]

Several Frankia genomes are now available which may help clarify how the symbiosis between prokaryote and plant evolved, how the environmental and geographical adaptations occurred, the metabolic diversity, and the horizontal gene flow among the symbiotic prokaryotes.[4]

Symbiont plants

References

  1. ↑ Brunchorst, J. "Uber einige Wurzelanschwellungen, besonders diejenigen von Alnus und den Elaegnaceen." Botanische Institut Tubingen (1886) 2:151-177.
  2. ↑ Pawlowski, Katharina (2009-06-17). Prokaryotic Symbionts in Plants. Springer Science & Business Media. p. 107. ISBN 9783540754602.
  3. ↑ Frankia taxonomy
  4. 1 2 Frankia and Actinorhizal Plants
  5. ↑ Schwintzer & Tjepkema 1990
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