Diversity and host specificity of Azolla cyanobionts

Papaefthimiou, Dimitra;Van Hove, Charles;Lejeune, André;Rasmussen, Ulla;Wilmotte, Annick
(2008) Journal of Phycology : an international journal of algal research — Vol. 44, n° 1, p. 60-70 (2008)

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  • Papaefthimiou, Dimitra
    Author
  • Van Hove, CharlesUCLouvain
    Author
  • Author
  • Rasmussen, Ulla
    Author
  • Wilmotte, Annick
    Author
Abstract
A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf-lobe of the plant. This association has been studied extensively, and questions have frequently been raised regarding the number and diversity of cyanobionts (cyanobacterial symbionts) among the different Azolla strains and species. In this work, denaturating gradient gel electrophoresis (DGGE) and a clone library based on the 16S rRNA gene were used to study the genetic diversity and host specificity of the cyanobionts in 35 Azolla strains covering a wide taxonomic and geographic range. DNA was extracted directly from the cyanobacterial packets, isolated after enzymatic digestion of the Azolla leaves. Our results indicated the existence of different cyanobiont strains among Azolla species, and diversity within a single Azolla species, independent of the geographic origin of the host. Furthermore, the cyanobiont exhibited host-species specificity and showed most divergence between the two sections of genus Azolla, Azolla and Rhizosperma. These findings are in agreement with the recent redefinition of the taxon Azolla cristata within the section Azolla. With regard to the taxonomic status of the cyanobiont, the genus Anabaena of the Nostocaceae family was identified as the closest relative by this work.
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Papaefthimiou, D., Van Hove, C., Lejeune, A., Rasmussen, U., & Wilmotte, A. (2008). Diversity and host specificity of Azolla cyanobionts. Journal of Phycology : an international journal of algal research, 44(1), 60-70. https://doi.org/10.1111/j.1529-8817.2007.00448.x (Original work published 2008)