Organic acids metabolism in Frankia alni
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Trophic exchanges constitute the bases of the symbiosis between the nitrogen-fixing actinomycete Frankia and its host plant Alnus, but the identity of the compounds exchanged is still poorly known. In the current work, previously published transcriptomic studies of Alnus nodules and of symbiotic Frankia were reexamined for TCA cycle related genes. The bacterial TCA enzyme genes were all upregulated, especially the succinyl-CoA synthase and the citrate synthase while on the plant side, none was significantly modified in nodules relative to non-inoculated roots. A preliminary metabolomics approach permitted to see that citrate, 2-oxoglutarate, succinate, malate and fumarate were all more abundant (FC (Fold change) = 5–70) in mature nitrogen-fixing nodules than in roots. In the evaluation of the uptake and metabolism of these organic acids, a significant change was observed in the morphology of nitrogen fixing vesicles in vitro: the dicarboxylates malate, succinate and fumarate induced the formation of larger vesicles than was the case with propionate. Moreover, the production of spores was also modified depending on the organic acid present. The assays showed that most C4 dicarboxylates were taken up while C6 tricarboxylates were not and citrate even partially blocked catabolism of reserve carbon. Tests were performed to determine if the change in membrane permeability induced by Ag5, a peptide previously shown to modify the membranes of Frankia, increased the uptake of specific organic acids. No effect was observed with citrate while an increase in nitrogen fixation was seen with propionate.
KeywordsDicarboxylates Frankia Propionate Nitrogen fixation Respiration Vesicles
We acknowledge grants from French ANR (BugsInACell ANR-13-BSV7-0013-03), from the FR BioEnvironment and Health (Lyon) and a MEC postdoctoral fellowship from the Spanish government to LC (Programa Nacional de Movilidad de Recursos Humanos del Plan Nacional de I-D + i 2008–2011). We thank AME, PGE and DTAMB platforms for measurements. TP and KP acknowledge a grant from the Swedish research council FORMAS (229-2005-679) and support by the Carl Tryggers Foundation.
Compliance with ethical standards
Conflict of Interest
Lorena Carro, Tomas Persson, Petar Pujic, Nicole Alloisio, Pascale Fournier, Hasna Boubakri, Katharina Pawlowski and Philippe Normand declare that they have no conflict of interest.
- Akkermans ADL, Huss-Danell K, Roelofsen W (1981) Enzymes of the tricarboxylic acid cycle and the malate-aspartate shuttle in the N2-fixing endophyte of Alnus glutinosa. Physiol Plant 53:289–294. doi: 10.1111/j.1399-3054.1981.tb04502.x
- Benjamini Y, Hochberg Y (1995) Controlling the false discovery rate: a practical and powerful approach to multiple testing. J Roy Statist Soc Ser B 57:289–300Google Scholar
- Berry AM, Harriott OT, Moreau RA, Osman SF, Benson DR, Jones AD (1993) Hopanoid lipids compose the Frankia vesicle envelope, presumptive barrier of oxygen diffusion to nitrogenase PNAS 90:6091–6094Google Scholar
- Carro L et al (2015) Alnus peptides modify membrane porosity and induce the release of nitrogen-rich metabolites from nitrogen-fixing Frankia. ISME J. doi: 10.1038/ismej.2014.257
- Guan C, Ribeiro A, Akkermans AD, Jing Y, van Kammen A, Bisseling T, Pawlowski K (1996) Nitrogen metabolism in actinorhizal nodules of Alnus glutinosa: expression of glutamine synthetase and acetylornithine transaminase. Plant Mol Biol 32:1177–1184Google Scholar
- Harris S, Silvester W (1992) Oxygen controls the development of Frankia vesicles in continuous culture. New Phytol 121:43–48Google Scholar
- Huss-Danell K (1997) Actinorhizal symbioses and their N2 fixation. New Phytol 136:375–405. doi: 10.1046/j.1469-8137.1997.00755.x
- Igual JM, Velazquez E, Mateos PF, Rodrıguez-Barrueco C, Cervantes E, Martınez-Molina E (2001) Cellulase isoenzyme profiles in Frankia strains belonging to different cross-inoculation groups. Plant Soil 229:35–39Google Scholar
- Mastronunzio J, Benson D (2010) Wild nodules can be broken: proteomics of Frankia in field-collected root nodules. Symbiosis 50:13–26. doi: 10.1007/s13199-009-0030-1
- Normand P, Orso S, Cournoyer B, Jeannin P, Chapelon C, Dawson J, Evtushenko L, Misra AK (1996) Molecular phylogeny of the genus Frankia and related genera and emendation of the family frankiaceae. IJSEM 46(1):1–9Google Scholar
- Sen A, Daubin V, Abrouk D, Gifford I, Berry AM, Normand P (2014) Phylogeny of the class Actinobacteria revisited in the light of complete genomes. The orders ‘Frankiales’ and Micrococcales should be split into coherent entities: proposal of Frankiales ord. nov., Geodermatophilales ord. nov., Acidothermales ord. nov. and Nakamurellales ord. Int J Syst Evol Microbiol 64:3821–3832. doi: 10.1099/ijs.0.063966-0 CrossRefPubMedGoogle Scholar
- Stowers M, Kulkarni R, Steele D (1986) Intermediary carbon metabolism in Frankia. Arch Microbiol 143:319–324Google Scholar
- Tjepkema JD, Schwintzer CR, Monz CA, (1988). Time course of acetylene reduction in nodules of five actinorhizal genera. Plant physiol 86(2):581–58Google Scholar
- Torrey JG, Callaham D (1982) Structural features of the vesicle of Frankia sp. CpI1 in culture. Can J Microbiol 28:749–757. doi: 10.1139/m82-114
- Vikman P-Å (1992) The symbiotic vesicle is a major site for respiration in Frankia from Alnus incana root nodules. Can J Microbiol 38:779–784. doi: 10.1139/m92-127