title: Strigolactones in the Rhizobium-legume symbiosis: Stimulatory effect on bacterial surface motility and down-regulation of their levels in nodulated plants.
abstract: Strigolactones (SLs) are multifunctional molecules acting as modulators of plant responses under nutrient deficient conditions. One of the roles of SLs is to promote beneficial association with arbuscular mycorrhizal (AM) fungi belowground under such stress conditions, mainly phosphorus shortage. Recently, a role of SLs in the Rhizobium-legume symbiosis has been also described. While SLs' function in AM symbiosis is well established, their role in the Rhizobium-legume interaction is still emerging. Recently, SLs have been suggested to stimulate surface motility of rhizobia, opening the possibility that they could also act as molecular cues. The possible effect of SLs in the motility in the alfalfa symbiont Sinorhizobium meliloti was investigated, showing that the synthetic SL analogue GR24 stimulates swarming motility in S. meliloti in a dose-dependent manner. On the other hand, it is known that SL production is regulated by nutrient deficient conditions and by AM symbiosis. Using the model alfalfa-S. meliloti, the impact of phosphorus and nitrogen deficiency, as well as of nodulation on SL production was also assessed. The results showed that phosphorus starvation promoted SL biosynthesis, which was abolished by nitrogen deficiency. In addition, a negative effect of nodulation on SL levels was detected, suggesting a conserved mechanism of SL regulation upon symbiosis establishment.
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas (EEZ-CSIC), Profesor Albareda 1, 18008 Granada, Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Peláez-Vico
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas (EEZ-CSIC), Profesor Albareda 1, 18008 Granada, Spain.
authors.forename: Lydia
authors.initials: L
authors.lastname: Bernabéu-Roda
authors.affiliation: Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: Kohlen
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas (EEZ-CSIC), Profesor Albareda 1, 18008 Granada, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Soto
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas (EEZ-CSIC), Profesor Albareda 1, 18008 Granada, Spain. Electronic address: juan.lopezraez@eez.csic.es.
authors.forename: Juan A
authors.initials: JA
authors.lastname: López-Ráez
mesh_terms: D015536:Down-Regulation / Q000187:drug effects*; D005408:Flagellin / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology*; D007783:Lactones / Q000494:pharmacology*; D000455:Medicago sativa / Q000382:microbiology*; D009068:Movement / Q000187:drug effects; D009584:Nitrogen / Q000172:deficiency; D010758:Phosphorus / Q000172:deficiency; D010933:Plankton / Q000187:drug effects / Q000378:metabolism; D055170:Plant Root Nodulation / Q000187:drug effects* / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000382:microbiology; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D013559:Symbiosis / Q000187:drug effects* / Q000235:genetics
chemical_list: C000591191:GR24 strigolactone; D006575:Heterocyclic Compounds, 3-Ring; D007783:Lactones; D005408:Flagellin; D010758:Phosphorus; D009584:Nitrogen
keywords: Alfalfa; Bacterial motility; Nodulation; Nutrient deficiency; Sinorhizobium meliloti; Strigolactones; Swarming