Open AccessGlobal Changes in Gene Expression in Sinorhizobium meliloti 1021 under Microoxic and Symbiotic Conditions
Author(s) -
Anke Becker,
Hélène Berges,
Elizaveta Krol,
Claude Bruand,
Silvia Rüberg,
Delphine Capela,
Emmanuelle Lauber,
Eliane Meilhoc,
Frédéric Ampe,
Frans J. de Bruijn,
Joëlle Fourment,
Anne FrancezCharlot,
Daniel Kahn,
H. Küster,
Carine Liebe,
Alfred Pühler,
Stefan Weidner,
Jacques Batut
Publication year - 2004
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi.2004.17.3.292
Subject(s) - sinorhizobium meliloti , biology , transcriptome , symbiosis , gene expression , nitrogen fixation , rhizosphere , gene , gene expression profiling , sinorhizobium , microbiology and biotechnology , genetics , bacteria , rhizobiaceae
Sinorhizobium meliloti is an α-proteobacterium that alternates between a free-living phase in bulk soil or in the rhizosphere of plants and a symbiotic phase within the host plant cells, where the bacteria ultimately differentiate into nitrogen-fixing organelle-like cells, called bacteroids. As a step toward understanding the physiology of S. meliloti in its free-living and symbiotic forms and the transition between the two, gene expression profiles were determined under two sets of biological conditions: growth under oxic versus microoxic conditions, and in free-living versus symbiotic state. Data acquisition was based on both macro- and microarrays. Transcriptome profiles highlighted a profound modification of gene expression during bacteroid differentiation, with 16% of genes being altered. The data are consistent with an overall slow down of bacteroid metabolism during adaptation to symbiotic life and acquisition of nitrogen fixation capability. A large number of genes of unknown function, including potential regulators, that may play a role in symbiosis were identified. Transcriptome profiling in response to oxygen limitation indicated that up to 5% of the genes were oxygen regulated. However, the microoxic and bacteroid transcriptomes only partially overlap, implying that oxygen contributes to a limited extent to the control of symbiotic gene expression.