AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chaintreuil, C.
Right arrow Articles by Dreyfus, B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chaintreuil, C.
Right arrow Articles by Dreyfus, B.
Agricola
Right arrow Articles by Chaintreuil, C.
Right arrow Articles by Dreyfus, B.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, December 2000, p. 5437-5447, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Photosynthetic Bradyrhizobia Are Natural Endophytes of the African Wild Rice Oryza breviligulata

Clémence Chaintreuil,1 Eric Giraud,1 Yves Prin,1 Jean Lorquin,2 Amadou Bâ,2 Monique Gillis,3 Philippe de Lajudie,1 and Bernard Dreyfus1,*

Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, INRA, AGRO-M, CIRAD, TA10/J, Campus International de Baillarguet, 34398 Montpellier cedex 5, France1; Laboratoire de Microbiologie, ISRA/IRD/UCAD, Dakar, Sénégal2; and Laboratorium voor Microbiologie, Universiteit Gent, Ghent, Belgium3

Received 6 April 2000/Accepted 31 August 2000

We investigated the presence of endophytic rhizobia within the roots of the wetland wild rice Oryza breviligulata, which is the ancestor of the African cultivated rice Oryza glaberrima. This primitive rice species grows in the same wetland sites as Aeschynomene sensitiva, an aquatic stem-nodulated legume associated with photosynthetic strains of Bradyrhizobium. Twenty endophytic and aquatic isolates were obtained at three different sites in West Africa (Senegal and Guinea) from nodal roots of O. breviligulata and surrounding water by using A. sensitiva as a trap legume. Most endophytic and aquatic isolates were photosynthetic and belonged to the same phylogenetic Bradyrhizobium/Blastobacter subgroup as the typical photosynthetic Bradyrhizobium strains previously isolated from Aeschynomene stem nodules. Nitrogen-fixing activity, measured by acetylene reduction, was detected in rice plants inoculated with endophytic isolates. A 20% increase in the shoot growth and grain yield of O. breviligulata grown in a greenhouse was also observed upon inoculation with one endophytic strain and one Aeschynomene photosynthetic strain. The photosynthetic Bradyrhizobium sp. strain ORS278 extensively colonized the root surface, followed by intercellular, and rarely intracellular, bacterial invasion of the rice roots, which was determined with a lacZ-tagged mutant of ORS278. The discovery that photosynthetic Bradyrhizobium strains, which are usually known to induce nitrogen-fixing nodules on stems of the legume Aeschynomene, are also natural true endophytes of the primitive rice O. breviligulata could significantly enhance cultivated rice production.

* Corresponding author. Mailing address: Laboratoire des Symbioses Tropicales et Méditerranéennes, TA10/J, Campus de Baillarguet, 34398 Montpellier cedex 5, France. Phone: 334 67 59 38 82. Fax: 334 67 59 38 02. E-mail: dreyfus{at}mpl.ird.fr.

Applied and Environmental Microbiology, December 2000, p. 5437-5447, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.