The Frankia alni symbiotic transcriptome.
The actinobacteria Frankia spp. are able to induce the formation of nodules on the roots of a large spectrum of actinorhizal plants, where they convert dinitrogen to ammonia in exchange for plant photosynthates. In the present study, transcriptional analyses were performed on nitrogen-replete free-living Frankia alni 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 spp. genomes, while nodule-repressed genes, which were mostly hypothetical and not conserved, were spread around the genome. Genes known to be related to nitrogen fixation 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, signaling processes, protein drug export, protein secretion, lipopolysaccharide, and peptidoglycan biosynthesis that may play a role in symbiosis were also identified. We also showed that this Frankia symbiotic transcriptome was highly similar among phylogenetically distant plant families Betulaceae and Myricaceae. Finally, comparison with rhizobia transcriptome suggested that F. alni is metabolically more active in symbiosis than rhizobia.
Alloisio
Nicole
N
Université de Lyon, Lyon, France.
Queiroux
Clothilde
C
Fournier
Pascale
P
Pujic
Petar
P
Normand
Philippe
P
Vallenet
David
D
Médigue
Claudine
C
Yamaura
Masatoshi
M
Kakoi
Kentaro
K
Kucho
Ken-ichi
K
D029661:Alnus / Q000235:genetics* / Q000382:microbiology*; D001692:Biological Transport / Q000235:genetics; D030541:Databases, Genetic; D040161:Frankia / Q000166:cytology / Q000235:genetics*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D018506:Gene Expression Regulation, Plant; D005798:Genes, Bacterial / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D009586:Nitrogen Fixation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D015203:Reproducibility of Results; D012231:Rhizobium / Q000235:genetics; D053204:Root Nodules, Plant / Q000235:genetics / Q000382:microbiology; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics*
D000644:Quaternary Ammonium Compounds