title: Pseudomonas fluorescens and Glomus mosseae trigger DMI3-dependent activation of genes related to a signal transduction pathway in roots of Medicago truncatula.
abstract: Plant genes induced during early root colonization of Medicago truncatula Gaertn. J5 by a growth-promoting strain of Pseudomonas fluorescens (C7R12) have been identified by suppressive subtractive hybridization. Ten M. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between M. truncatula and P. fluorescens, up to 8 d after root inoculation. Gene expression was not significantly enhanced, except for one gene, in P. fluorescens-inoculated roots of a Myc(-)Nod(-) genotype (TRV25) of M. truncatula mutated for the DMI3 (syn. MtSYM13) gene. This gene codes a Ca(2+) and calmodulin-dependent protein kinase, indicating a possible role of calcium in the cellular interactions between M. truncatula and P. fluorescens. When expression of the 10 plant genes was compared in early stages of root colonization by mycorrhizal and rhizobial microsymbionts, Glomus mosseae activated all 10 genes, whereas Sinorhizobium meliloti only activated one and inhibited four others. None of the genes responded to inoculation by either microsymbiont in roots of the TRV25 mutant. The similar response of the M. truncatula genes to P. fluorescens and G. mosseae points to common molecular pathways in the perception of the microbial signals by plant roots.
authors.affiliation: Unité Mixte de Recherche, Institut National de la Recherche Agronomique 1088/Centre National de la Recherche Scientifique 5184/Université de Bourgogne Plante-Microbe-Environnement, Dijon, France.
authors.forename: Lisa
authors.initials: L
authors.lastname: Sanchez
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Weidmann
authors.forename: Christine
authors.initials: C
authors.lastname: Arnould
authors.forename: Anne Rose
authors.initials: AR
authors.lastname: Bernard
authors.forename: Silvio
authors.initials: S
authors.lastname: Gianinazzi
authors.forename: Vivienne
authors.initials: V
authors.lastname: Gianinazzi-Pearson
mesh_terms: D001483:Base Sequence; D018744:DNA, Plant / Q000235:genetics; D005658:Fungi / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005838:Genotype; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology*; D008969:Molecular Sequence Data; D009154:Mutation; D018517:Plant Roots / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000502:physiology*; D015398:Signal Transduction; D016962:Sinorhizobium meliloti / Q000502:physiology; D013559:Symbiosis
chemical_list: D018744:DNA, Plant