title: Plant-mediated interspecific horizontal transmission of an intracellular symbiont in insects.
abstract: Intracellular reproductive manipulators, such as Candidatus Cardinium and Wolbachia are vertically transmitted to progeny but rarely show co-speciation with the host. In sap-feeding insects, plant tissues have been proposed as alternative horizontal routes of interspecific transmission, but experimental evidence is limited. Here we report results from experiments that show that Cardinium is horizontally transmitted between different phloem sap-feeding insect species through plants. Quantitative PCR and in situ hybridization experiments indicated that the leafhopper Scaphoideus titanus releases Cardinium from its salivary glands during feeding on both artificial media and grapevine leaves. Successional time-course feeding experiments with S. titanus initially fed sugar solutions or small areas of grapevine leaves followed by feeding by the phytoplasma vector Macrosteles quadripunctulatus or the grapevine feeder Empoasca vitis revealed that the symbionts were transmitted to both species. Explaining interspecific horizontal transmission through plants improves our understanding of how symbionts spread, their lifestyle and the symbiont-host intermixed evolutionary pattern.
authors.affiliation: Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, 10095 Grugliasco.
authors.forename: Elena
authors.initials: E
authors.lastname: Gonella
authors.affiliation: Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, 10095 Grugliasco.
authors.forename: Massimo
authors.initials: M
authors.lastname: Pajoro
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione, l'Ambiente (DeFENS), Università degli Studi di Milano, 20133 Milan.
authors.forename: Massimo
authors.initials: M
authors.lastname: Marzorati
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione, l'Ambiente (DeFENS), Università degli Studi di Milano, 20133 Milan.
authors.forename: Elena
authors.initials: E
authors.lastname: Crotti
authors.affiliation: Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, 41100 Modena.
authors.forename: Mauro
authors.initials: M
authors.lastname: Mandrioli
authors.affiliation: Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, 10095 Grugliasco.
authors.forename: Marianna
authors.initials: M
authors.lastname: Pontini
authors.affiliation: Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Università degli Studi di Milano, 20133 Milan.
authors.forename: Daniela
authors.initials: D
authors.lastname: Bulgari
authors.affiliation: Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, 10095 Grugliasco.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Negri
authors.affiliation: Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università degli Studi di Pavia, 27100 Pavia.
authors.forename: Luciano
authors.initials: L
authors.lastname: Sacchi
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione, l'Ambiente (DeFENS), Università degli Studi di Milano, 20133 Milan.
authors.forename: Bessem
authors.initials: B
authors.lastname: Chouaia
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione, l'Ambiente (DeFENS), Università degli Studi di Milano, 20133 Milan.|King Abdullah University of Science and Technology, BESE Division, Thuwal, 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Daniele
authors.initials: D
authors.lastname: Daffonchio
authors.affiliation: Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, 10095 Grugliasco.
authors.forename: Alberto
authors.initials: A
authors.lastname: Alma
mesh_terms: D000818:Animals; D041963:Bacteroidetes / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005843:Geography; D006430:Hemiptera / Q000235:genetics / Q000382:microbiology* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D007303:Insect Vectors / Q000382:microbiology / Q000502:physiology; D042541:Intracellular Space / Q000382:microbiology / Q000469:parasitology; D007558:Italy; D046529:Microscopy, Electron, Transmission; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology / Q000469:parasitology; D018515:Plant Leaves / Q000382:microbiology / Q000469:parasitology; D010944:Plants / Q000382:microbiology* / Q000469:parasitology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012469:Salivary Glands / Q000382:microbiology; D013559:Symbiosis; D027843:Vitis / Q000382:microbiology / Q000469:parasitology
chemical_list: D012336:RNA, Ribosomal, 16S