Comparison of transcriptome between free-living and symbiotic cells of Frankia alni ACN14a

ABSTRACT: The actinobacteria Frankia alni is able to induce the formation of nodules on the root of a large spectrum of actinorhizal plants, where it converts dinitrogen to ammonia in exchange for plant photosynthates. In the present study, transcriptional analyses were performed on nitrogen-replete free-living cells and on Alnus glutinosa nodule bacteria, using whole genome microarrays. Distribution of nodule-induced genes on the genome was found to be mostly over regions with high synteny between three Frankia genomes, while nodule-repressed genes, which were mostly hypothetical and not conserved, were spread around the genome. Genes known to be related to symbiosis were highly induced: nif (nitrogenase), hup2 (hydrogenase uptake), suf (sulfur-iron cluster) and shc (hopanoids synthesis). The expression of genes involved in ammonium assimilation and transport was strongly modified suggesting that bacteria ammonium assimilation was limited. Genes involved in particular in transcriptional regulation, signalling processes, protein drug export, protein secretion, lipopolysaccharide and peptidoglycan biosynthesis that may play a role in symbiosis were also identified. We showed that this nodule transcriptome of Frankia was highly similar among phylogenetically distant plant families. To address gene expression changes of Frankia alni ACN in the symbiotic state, we compared transcript levels between young nodules formed on 4 species of trees (Alnus glutinosa, Alnus nepalensis, Myrica gale and Myrica rubra) and free-living cells grown in nitrogen-replete minimal medium. For A. glutinosa nodule and free-living cells, two sets of experiments (A and B) were performed in two different laboratories. Three biological replicates were preformed for each condition.

ORGANISM(S): Frankia alni ACN14a

SUBMITTER: Ken-ichi Kucho 

PROVIDER: E-GEOD-18190 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress