Nod genes are required for the colonization of different hosts by Rhizobium sp. IRBG74
M. CROOK (1), A. Wiley-Kalil (2), V. Poinsot (3), S. Erdn (4), K. Garcia (1), M. Babcock (1), J. Maeda (1), A. Desbiez-Piat (2), F. Maillet (4), A. Mukherjee (5), J. Dénarié (4), J. Ané (1) (1) Department of Bacteriology, University of Wisconsin–Madison, U.S.A.; (2) Department of Agronomy, University of Wisconsin–Madison, U.S.A.; (3) Laboratoire des IMRCP, Université Paul Sabatier, France; (4) Laboratoire des Interactions Plantes–Microorganismes, INRA-CNRS, France; (5) Department of Biology, University of Central Arkansas, U.S.A.

Rhizobium sp. IRBG74 is capable of nodulating and fixing nitrogen in association with several legume species of the genus Sesbania. It has also been found to colonize rice as an epiphyte and an endophyte and promote rice growth, though nitrogen is not fixed in this non-legume host. As expected, the Nod factors of Rhizobium sp. IRBG74 are required for nodulation of the original host, Sesbania cannabina, as well as the model legume, Lotus japonicus. Here we show that chitin oligomers produced by Rhizobium sp. IRBG74 play a role in colonization of the root surface of the non-legume host, rice. Furthermore, we show that colonization of rice roots by Rhizobium sp. IRBG74 involves host components that are also required for colonization by another class of symbiotic microbes, arbuscular mycorrhizal fungi. We also present symbiotic responses in rice roots produced upon perception of Nod factors purified from Rhizobium sp. IRBG74. Thus the recently sequenced genome of Rhizobium sp. IRBG74 is enabling us to conduct a reverse genetics approach to analyze the role of specific nod genes in the symbiotic association with two distinct hosts: a legume (Sesbania cannabina) and a cereal (rice).

Abstract Number: P2-20
Session Type: Poster