title: The Sinorhizobium (Ensifer) fredii HH103 Type 3 Secretion System Suppresses Early Defense Responses to Effectively Nodulate Soybean.
abstract: Plants that interact with pathogenic bacteria in their natural environments have developed barriers to block or contain the infection. Phytopathogenic bacteria have evolved mechanisms to subvert these defenses and promote infection. Thus, the type 3 secretion system (T3SS) delivers bacterial effectors directly into the plant cells to alter host signaling and suppress defenses, providing an appropriate environment for bacterial multiplication. Some rhizobial strains possess a symbiotic T3SS that seems to be involved in the suppression of host defenses to promote nodulation and determine the host range. In this work, we show that the inactivation of the Sinorhizobium (Ensifer) fredii HH103 T3SS negatively affects soybean nodulation in the early stages of the symbiotic process, which is associated with a reduction of the expression of early nodulation genes. This symbiotic phenotype could be the consequence of the bacterial triggering of soybean defense responses associated with the production of salicylic acid (SA) and the impairment of the T3SS mutant to suppress these responses. Interestingly, the early induction of the transcription of GmMPK4, which negatively regulates SA accumulation and defense responses in soybean via WRKY33, could be associated with the differential defense responses induced by the parental and the T3SS mutant strain.
authors.affiliation: 1 Departamento de Microbiología, and.
authors.forename: Irene
authors.initials: I
authors.lastname: Jiménez-Guerrero
authors.affiliation: 1 Departamento de Microbiología, and.
authors.forename: Francisco
authors.initials: F
authors.lastname: Pérez-Montaño
authors.affiliation: 2 Departamento de Fisiología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Sevilla, Spain;
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Monreal
authors.affiliation: 3 Department of Plant Sciences, University of Oxford, OX1 3RB, Oxford, United Kingdom; and.
authors.forename: Gail M
authors.initials: GM
authors.lastname: Preston
authors.affiliation: 3 Department of Plant Sciences, University of Oxford, OX1 3RB, Oxford, United Kingdom; and.
authors.forename: Helen
authors.initials: H
authors.lastname: Fones
authors.affiliation: 4 Departamento de Fitoquímica de Alimentos, Instituto de la Grasa (CSIC), Avda. Padre García Tejero, 4, 41012, Sevilla, Spain.
authors.forename: Blanca
authors.initials: B
authors.lastname: Vioque
authors.affiliation: 1 Departamento de Microbiología, and.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Ollero
authors.affiliation: 1 Departamento de Microbiología, and.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: López-Baena
mesh_terms: D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D007532:Isoleucine / Q000378:metabolism; D009154:Mutation; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D020156:Salicylic Acid / Q000378:metabolism; D042181:Sinorhizobium fredii / Q000472:pathogenicity* / Q000502:physiology*; D013025:Glycine max / Q000235:genetics / Q000382:microbiology*; D013559:Symbiosis / Q000235:genetics
chemical_list: D007532:Isoleucine; D020156:Salicylic Acid