title: Differential expression of Spiroplasma citri surface protein genes in the plant and insect hosts.
abstract: BACKGROUND
  Spiroplasma citri is a cell wall-less, plant pathogenic bacteria that colonizes two distinct hosts, the leafhopper vector and the host plant. Given the absence of a cell wall, surface proteins including lipoproteins and transmembrane polypeptides are expected to play key roles in spiroplasma/host interactions. Important functions in spiroplasma/insect interactions have been shown for a few surface proteins such as the major lipoprotein spiralin, the transmembrane S. citri adhesion-related proteins (ScARPs) and the sugar transporter subunit Sc76. S. citri efficient transmission from the insect to the plant is expected to rely on its ability to adapt to the different environments and more specifically to regulate the expression of genes encoding surface-exposed proteins.
  
  
  RESULTS
  Genes encoding S. citri lipoproteins and ScARPs were investigated for their expression level in axenic medium, in the leafhopper vector Circulifer haematoceps and in the host plant (periwinkle Catharanthus roseus) either insect-infected or graft-inoculated. The vast majority of the lipoprotein genes tested (25/28) differentially responded to the various host environments. Considering their relative expression levels in the different environments, the possible involvement of the targeted genes in spiroplasma host adaptation was discussed. In addition, two S. citri strains differing notably in their ability to express adhesin ScARP2b and pyruvate dehydrogenase E1 component differed in their capacity to multiply in the two hosts, the plant and the leafhopper vector.
  
  
  CONCLUSIONS
  This study provided us with a list of genes differentially expressed in the different hosts, leading to the identification of factors that are thought to be involved in the process of S. citri host adaptation. The identification of such factors is a key step for further understanding of S. citri pathogenesis. Moreover the present work highlights the high capacity of S. citri in tightly regulating the expression level of a large set of surface protein genes, despite the small size of its genome.
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Dubrana
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France. laure.beven@bordeaux.inra.fr.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France. laure.beven@bordeaux.inra.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Béven
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Arricau-Bouvery
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France.
authors.forename: Sybille
authors.initials: S
authors.lastname: Duret
authors.affiliation: Plateforme Protéome, CGFB, Université de Bordeaux, F-33076, Bordeaux, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Claverol
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France.
authors.forename: Joël
authors.initials: J
authors.lastname: Renaudin
authors.affiliation: UMR 1332 Biologie du Fruit et Pathologie, INRA, F-33882, Villenave d'Ornon, France.|UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, F-33882, Villenave d'Ornon, France.
authors.forename: Colette
authors.initials: C
authors.lastname: Saillard
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D006430:Hemiptera / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D007303:Insect Vectors / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D045642:Spiroplasma citri / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins
keywords: Adhesins; Gene expression; Lipoproteins; Spiroplasma; Spiroplasma citri