title: Stable isotope labelling reveals that NaCl stress decreases the production of Ensifer (Sinorhizobium) arboris lipochitooligosaccharide signalling molecules.
abstract: Ensifer (Sinorhizobium) arboris is a symbiont of salt-tolerant leguminous trees in the genera Acacia and Prosopis that are utilized in the prevention of soil erosion and desertification and in phytoremediation of salinized soil. Signalling between the plant and the rhizobia is essential for the formation of effective symbiosis that increases the success of reclaiming saline sites. We assessed the effect of salt stress on the growth and the production of lipochitooligosaccharide signalling molecules (LCOs) of S. arboris HAMBI 2361, an LCO-overproducing derivative of the S. arboris type strain HAMBI 1552. The strain tolerated NaCl up to 750 mM. To obtain both qualitative and quantitative information on the LCO production under salt stress, we devised a method where LCOs were differentially labelled by stable isotopes of nitrogen, (14)N and (15)N, and analysed by mass spectrometry. Under control conditions, the strain produced altogether 27 structural LCO variants. In 380 mM NaCl, 13 LCO variants were produced in detectable amounts, and six of these were reliably quantified, ranging from one-tenth to one-third of the non-stressed one.
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Penttinen
authors.forename: Leena A
authors.initials: LA
authors.lastname: Räsänen
authors.forename: Gilles
authors.initials: G
authors.lastname: Lortet
authors.forename: Kristina
authors.initials: K
authors.lastname: Lindström
mesh_terms: D007553:Isotope Labeling; D008070:Lipopolysaccharides / Q000378:metabolism*; D013058:Mass Spectrometry; D055432:Metabolomics; D055049:Salt Tolerance / Q000502:physiology*; D020579:Sinorhizobium / Q000187:drug effects / Q000502:physiology*; D012965:Sodium Chloride / Q000378:metabolism* / Q000494:pharmacology; D013312:Stress, Physiological
chemical_list: D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D012965:Sodium Chloride
keywords: Acacia; Prosopis; nod factor; salt stress; symbiosis