title: Responses to elevated c-di-GMP levels in mutualistic and pathogenic plant-interacting bacteria.
abstract: Despite a recent burst of research, knowledge on c-di-GMP signaling pathways remains largely fragmentary and molecular mechanisms of regulation and even c-di-GMP targets are yet unknown for most bacteria. Besides genomics or bioinformatics, accompanying alternative approaches are necessary to reveal c-di-GMP regulation in bacteria with complex lifestyles. We have approached this study by artificially altering the c-di-GMP economy of diverse pathogenic and mutualistic plant-interacting bacteria and examining the effects on the interaction with their respective host plants. Phytopathogenic Pseudomonas and symbiotic Rhizobium strains with enhanced levels of intracellular c-di-GMP displayed common free-living responses: reduction of motility, increased production of extracellular polysaccharides and enhanced biofilm formation. Regarding the interaction with the host plants, P. savastanoi pv. savastanoi cells containing high c-di-GMP levels formed larger knots on olive plants which, however, displayed reduced necrosis. In contrast, development of disease symptoms in P. syringae-tomato or P. syringae-bean interactions did not seem significantly affected by high c-di-GMP. On the other hand, increasing c-di-GMP levels in symbiotic R. etli and R. leguminosarum strains favoured the early stages of the interaction since enhanced adhesion to plant roots, but decreased symbiotic efficiency as plant growth and nitrogen contents were reduced. Our results remark the importance of c-di-GMP economy for plant-interacting bacteria and show the usefulness of our approach to reveal particular stages during plant-bacteria associations which are sensitive to changes in c-di-GMP levels.
authors.affiliation: Dpto. Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pérez-Mendoza
authors.affiliation: Área de Genética, Universidad de Málaga, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga-CSIC (IHSM-UMA-CSIC), Málaga, Spain.
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Aragón
authors.affiliation: Dpto. Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain.
authors.forename: Harold A
authors.initials: HA
authors.lastname: Prada-Ramírez
authors.affiliation: Dpto. Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Romero-Jiménez
authors.affiliation: Área de Genética, Universidad de Málaga, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga-CSIC (IHSM-UMA-CSIC), Málaga, Spain.
authors.forename: Cayo
authors.initials: C
authors.lastname: Ramos
authors.affiliation: Dpto. Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain.
authors.forename: María-Trinidad
authors.initials: MT
authors.lastname: Gallegos
authors.affiliation: Dpto. Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Sanjuán
mesh_terms: D000464:Alginates / Q000737:chemistry; D001426:Bacterial Proteins / Q000378:metabolism; D001557:Benzenesulfonates / Q000737:chemistry; D018441:Biofilms / Q000254:growth & development; D002482:Cellulose / Q000737:chemistry; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D018551:Solanum lycopersicum / Q000382:microbiology; D009154:Mutation; D031658:Olea / Q000382:microbiology; D027805:Phaseolus / Q000382:microbiology; D010641:Phenotype; D018517:Plant Roots / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D011549:Pseudomonas / Q000378:metabolism* / Q000472:pathogenicity; D012231:Rhizobium / Q000378:metabolism*; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics
chemical_list: D000464:Alginates; D001426:Bacterial Proteins; D001557:Benzenesulfonates; D005456:Fluorescent Dyes; C062025:bis(3',5')-cyclic diguanylic acid; C007061:C.I. Fluorescent Brightening Agent 28; D002482:Cellulose; D006152:Cyclic GMP