Vector transmission of a plant-pathogenic bacterium in the Arsenophonus clade sharing ecological traits with facultative insect endosymbionts.

The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the major vector of a nonculturable plant-pathogenic gamma-3 proteobacterium associated with a disease of sugar beet called syndrome "basses richesses" (SBR). The bacterium, here called SBR bacterium, belongs to the Arsenophonous clade, which includes mostly insect-associated facultative symbionts. Assays using field-collected planthopper nymphs and adults were carried out to investigate the interaction of SBR bacterium with the insect vector and its transmission to sugar beet.

Characterization and evolution of two bacteriome-inhabiting symbionts in cixiid planthoppers (Hemiptera: Fulgoromorpha: Pentastirini).

Like other plant sap-sucking insects, planthoppers within the family Cixiidae (Insecta: Hemiptera: Fulgoromorpha) host a diversified microbiota. We report the identification and first molecular characterization of symbiotic bacteria in cixiid planthoppers (tribe: Pentastirini). Using universal eubacterial primers we first screened the eubacterial 16S rRNA sequences in Pentastiridius leporinus (Linnaeus) with PCR amplification, cloning, and restriction fragment analysis.

Insect injection and artificial feeding bioassays to test the vector specificity of flavescence dorée phytoplasma.

ABSTRACT The specificity of vector transmission of Flavescence dorée phytoplasma (FDP) was tested by injecting FDP, extracted from laboratory-reared infective Euscelidius variegatus, into specimens of 15 other hemipteran insect species collected in European vineyards. Concentrations of viable phytoplasma extracts and latency in vectors were monitored by injection of healthy-reared E. variegatus leafhoppers.

Characterization of a gamma-3 Proteobacteria Responsible for the Syndrome "Basses Richesses" of Sugar Beet Transmitted by Pentastiridius sp. (Hemiptera, Cixiidae).

ABSTRACT The disease syndrome "basses richesses" (SBR) has affected sugar beet crops in Burgundy (France) since 1991. It mainly is associated with an uncultivable phloem-restricted bacterium-like organism (BLO) called SBR BLO. Transmission tests showed that field-collected Pentastiridius sp.

A chromosome map of the Flavescence doree phytoplasma.

The Flavescence dorée phytoplasma (FD-P), a non-cultivable, plant-pathogenic bacterium of the class Mollicutes, is the causal agent of a quarantine disease affecting vineyards of southern Europe, mainly in southern France and northern Italy. To investigate FD-P diversity and phytoplasma genetic determinants governing the FD-P life cycle, a genome project has been initiated. A physical map of the chromosome of FD-P strain FD92, purified from infected broad beans, was constructed by performing restriction digests of the chromosome and resolving the fragments by PFGE.

Insect Vectors (Hemiptera: Cixiidae) and Pathogens Associated with the Disease Syndrome "Basses Richesses" of Sugar Beet in France.

The syndrome "basses richesses" (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied.

Multilocus sequence typing confirms the close genetic interrelatedness of three distinct flavescence dorée phytoplasma strain clusters and group 16SrV phytoplasmas infecting grapevine and alder in Europe.

Vineyards of southern France and northern Italy are affected by the flavescence dorée (FD) phytoplasma, a quarantine pathogen transmitted by the leafhopper of Nearctic origin Scaphoideus titanus. To better trace propagation of FD strains and identify possible passage between the vineyard and wild plant compartments, molecular typing of phytoplasma strains was applied. The sequences of the two genetic loci map and uvrB-degV, along with the sequence of the secY gene, were determined among a collection of FD and FD-related phytoplasmas infecting grapevine, alder, elm, blackberry, and Spanish broom in Europe.

Effect of two strains of Flavescence dorée phytoplasma on the survival and fecundity of the experimental leafhopper vector Euscelidius variegatus Kirschbaum.

We have investigated the influence on longevity and fecundity of Flavescence dorée phytoplasma (FDP), the agent of a grapevine yellows disease, in the experimental vector Euscelidius variegatus Kirschbaum. Late instar nymphs were exposed to one or the other of two strains of FDP (FD92 and FD2000) by feeding on infected broad bean (Vicia faba L.) or on healthy broad bean or maize (Zea mays L.