This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bianciotto, V. Articles by Bonfante, P. Search for Related Content PubMed PubMed Citation Articles by Bianciotto, V. Articles by Bonfante, P. Agricola Articles by Bianciotto, V. Articles by Bonfante, P.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, June 2004, p. 3600-3608, Vol. 70, No. 6
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.6.3600-3608.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Vertical Transmission of Endobacteria in the Arbuscular Mycorrhizal Fungus Gigaspora margarita through Generation of Vegetative Spores

V. Bianciotto,^1, A. Genre,^1, P. Jargeat,² E. Lumini,¹ G. Bécard,² and P. Bonfante^1*

Dipartimento di Biologia Vegetale dell'Università and Istituto per la Protezione delle Piante, CNR, 10125 Turin, Italy,¹ UMR 5546 CNRS/University Paul Sabatier, 31326 Auzeville, Castanet-Tolosan, France²

Received 8 December 2003/ Accepted 3 March 2004

Arbuscular mycorrhizal (AM) fungi living in symbiotic association with the roots of vascular plants have also been shown to host endocellular rod-shaped bacteria. Based on their ribosomal sequences, these endobacteria have recently been identified as a new taxon, Candidatus Glomeribacter gigasporarum. In order to investigate the cytoplasmic stability of the endobacteria in their fungal host and their transmission during AM fungal reproduction (asexual), a system based on transformed carrot roots and single-spore inocula of Gigaspora margarita was used. Under these in vitro sterile conditions, with no risk of horizontal contamination, the propagation of endobacteria could be monitored, and it was shown, by using primers designed for both 16S and 23S ribosomal DNAs, to occur through several vegetative spore generations (SG0 to SG4). A method of confocal microscopy for quantifying the density of endobacteria in spore cytoplasm was designed and applied; endobacteria were consistently found in all of the spore generations, although their number rapidly decreased from SG0 to SG4. The study demonstrates that a vertical transmission of endobacteria takes place through the fungal vegetative generations (sporulation) of an AM fungus, indicating that active bacterial proliferation occurs in the coenocytic mycelium of the fungus, and suggests that these bacteria are obligate endocellular components of their AM fungal host.

---

* Corresponding author. Mailing address: Dipartimento di Biologia Vegetale dell'Università e Istituto per la Protezione delle Piante CNR, Viale Mattioli 25, 10125 Turin, Italy. Phone: 39 011 6705965 or 39 011 6502927. Fax: 39 011 6705962. E-mail: p.bonfante{at}ipp.cnr.it.

V.B. and A.G. contributed equally to this work.

---

Applied and Environmental Microbiology, June 2004, p. 3600-3608, Vol. 70, No. 6
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.6.3600-3608.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Lanfranco, L., Novero, M., Bonfante, P. (2005). The Mycorrhizal Fungus Gigaspora margarita Possesses a CuZn Superoxide Dismutase That Is Up-Regulated during Symbiosis with Legume Hosts. Plant Physiol. 137: 1319-1330 [Abstract] [Full Text]  
• Jargeat, P., Cosseau, C., Ola'h, B., Jauneau, A., Bonfante, P., Batut, J., Becard, G. (2004). Isolation, Free-Living Capacities, and Genome Structure of "Candidatus Glomeribacter gigasporarum," the Endocellular Bacterium of the Mycorrhizal Fungus Gigaspora margarita. J. Bacteriol. 186: 6876-6884 [Abstract] [Full Text]