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APPLIED AND ENVIRONMENTAL MICROBIOLOGY
Vol. 72, No. 2, 2006; Pages: 1467–1475


A Novel Bacteroidetes Symbiont Is Localized in Scaphoideus titanus, the Insect Vector of Flavescence Doree in Vitis vinifera

Massimo Marzorati,1 Alberto Alma,2 Luciano Sacchi,3 Massimo Pajoro,2 Simona Palermo,2 Lorenzo Brusetti,1 Noura Raddadi,1 Annalisa Balloi,1 Rosemarie Tedeschi,2
Emanuela Clementi,3 Silvia Corona,3 Fabio Quaglino,4 Piero Attilio Bianco,4
Tiziana Beninati,5 Claudio Bandi,5 and Daniele Daffonchio1*

Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Via Celoria 2, 20133 Milan,
Italy.

Abstract

Flavescence doree (FD) is a grapevine disease that afflicts several wine production areas in Europe, from Portugal to Serbia. FD is caused by a bacterium, “Candidatus Phytoplasma vitis,” which is spread throughout the vineyards by a leafhopper, Scaphoideus titanus (Cicadellidae). After collection of S. titanus specimens from FD-contaminated vineyards in three different areas in the Piedmont region of Italy, we performed a survey to characterize the bacterial microflora associated with this insect. Using length heterogeneity PCR with universal primers for bacteria we identified a major peak associated with almost all of the individuals examined (both males and females). Characterization by denaturing gradient gel electrophoresis confirmed the presence of a major band that, after sequencing, showed a 97 to 99% identity with Bacteroidetes symbionts of the “Candidatus Cardinium hertigii” group. In addition, electron microscopy of tissues of S. titanus fed for 3 months on phytoplasma-infected grapevine plants showed bacterial cells with the typical morphology of “Ca. Cardinium hertigii.” This endosymbiont, tentatively designated ST1-C, was found in the cytoplasm of previtellogenic and vitellogenic ovarian cells, in the follicle cells, and in the fat body and salivary glands. In addition, cell morphologies resembling those of “Ca. Phytoplasma vitis” were detected in the midgut, and specific PCR assays indicated the presence of the phytoplasma in the gut, fat body and salivary glands. These results indicate that ST1-C and “Ca. Phytoplasma vitis” have a complex life cycle in the body of S. titanus and are colocalized in different organs and tissues.

Keywords:Flavescence doree;Candidatus Phytoplasma vitis;Rickettsia rickettsii;Scaphoideus titanus;Bacteroidetes;Ca. Phytoplasma;Dermacentor andersoni;plant pathogen phytoplasmas;taxonomy.


Corresponding author: Tel 39-0250316730; Fax 39-0250316694

E-mail: daniele .daffonchio@unimi.it

 

 
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