*** Welcome to piglix ***

Frankia alni

Frankia alni
Alder nodules2.JPG
Nodules caused by Frankia alni on roots of common alder Alnus glutinosa
Scientific classification
Kingdom: Bacteria
Phylum: Actinobacteria
Order: Actinomycetales
Suborder: Frankineae
Family: Frankiaceae
Genus: Frankia
Species: F. alni
Binomial name
Frankia alni
(Woronin, 1866) Von Tubeuf, 1895
Synonyms
  • Actinomyces alni (Woronin, 1866) Roberg, 1934
  • Aktinomyces alni (Woronin 1866) Peklo, 1910
  • Frankia subtilis Brunchorst 1886
  • Frankiella alni (Woronin, 1866) Maire and Tison, 1909
  • Nocardia alni (Woronin, 1866) Waksman, 1961
  • Plasmodiophora alni (Woronin, 1866) Moller, 1885
  • Proactinomyces alni (Woronin, 1866) Krasil'nikov, 1941
  • Schinzia alni Woronin, 1866
  • Streptomyces alni (Woronin, 1866) Fiuczek, 1959

Frankia alni is a species of actinomycete filamentous bacterium that lives in symbiosis with actinorhizal plants in the genus Alnus. It is a nitrogen-fixing bacterium and forms nodules on the roots of alder trees.

Frankia alni forms a symbiotic relationship exclusively with trees in the genus Alnus. These are widely distributed in temperate regions of the northern hemisphere. One species, Alnus glutinosa, is also found in Africa and another, the Andean alder, Alnus acuminata, extends down the mountainous spine of Central and South America as far as Argentina. Evidence suggests that this alder may have been exploited by the Incas and used to increase soil fertility and stabilize terrace soils in their upland farming systems.Alnus species grow in a wide range of habitats that include glacial till, sand hills, the banks of water courses, bogs, dry volcanic lava flows and ash alluvium.

The first symptom of infection by Frankia alni is a branching and curling of the root hairs of the alder as the bacterium moves in. The bacterium becomes encapsulated with a material derived from the plant cell wall and remains outside the host's cell membrane. The encapsulation membrane contains pectin, cellulose and hemicellulose. Cell division is stimulated in the hypodermis and cortex, which leads to the formation of a "prenodule". The bacterium then migrates into the cortex of the root while the nodule continues to develop in the same way as a lateral root. Nodule lobe primordia develop in the pericycle, endodermis or cortex during the development of the prenodule and finally the bacterium enters the cells of these to infect the new nodule.


...
Wikipedia

...