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Bertin S.,University of Turin | Picciau L.,University of Turin | Acs Z.,Fitolab Plant Pest Diagnostic and Advisory Ltd. | Alma A.,University of Turin | Bosco D.,University of Turin
Annals of Applied Biology | Year: 2010

The insect family Cixiidae includes economically important vectors of plant pathogens. Hyalesthes obsoletus transmits the stolbur phytoplasma (16SrXII-A genetic group) associated with a serious grapevine yellows disease known as Bois Noir (BN). Other cixiids are currently suspected to be BN vectors, and the correct identification of Hyalesthes species present in vineyards is essential for epidemiological surveys. This study aims to discriminate between H. obsoletus, Hyalesthes luteipes and Hyalesthes scotti by integrating their morphological descriptions with new molecular assays. The sole amplification of a ribosomal internal transcribed spacer 2 (ITS2) region was enough to discriminate between H. luteipes and H. scotti, which are externally indistinguishable. Alternatively, PCR-restriction fragment length polymorphism (RFLP) assays carried out on the mitochondrial cytochrome oxidase I gene (COI) with TaqI provided species-specific profiles for all three Hyalesthes species. These molecular identification keys proved to be fast and reliable and can contribute to broaden the current handful of entomologists involved in cixiid identification. Furthermore, these markers can also be successfully applied to nymphs, whose morphological distinctive traits are unavailable. The identification of nymphs greatly extends the vector monitoring period and allows the unambiguous association with the actual host plants. Thus, these molecular tools will help monitoring activities and the rational control of potential stolbur vectors. The same ITS2 and COI sequences have been analysed at an intraspecific level for H. obsoletus to identify possible different populations involved in different epidemiological cycles of BN. Both markers confirmed a high degree of genetic conservation within the species and could not characterise populations living on different host plants and transmitting different phytoplasmas strains. © 2010 Association of Applied Biologists. Source

Bertin S.,University of Turin | Picciau L.,University of Turin | Acs Z.,Fitolab Plant Pest Diagnostic and Advisory Ltd. | Alma A.,University of Turin | Bosco D.,University of Turin
Bulletin of Entomological Research | Year: 2010

The cixiid species Reptalus quinquecostatus, R. cuspidatus, R. panzeri and R. melanochaetus are widely distributed in Europe and are receiving growing attention because of their potential role as phytoplasma vectors. Identifying the Reptalus species is restricted to a few specialist entomologists and relies on the morphology of the male genitalia, hampering the identification of juveniles and females. This study provides the tools for species discrimination by integrating the morphological description, which is primarily for the genus identification, with new molecular assays, based on both ribosomal and mitochondrial DNA. PCR-RFLP assays carried out on the mitochondrial cytochrome oxidase I gene (COI) with AluI provided species-specific profiles for the four Reptalus species. Amplification of a ribosomal internal transcribed spacer (ITS2) region produced species-specific fragments of different sizes for R. quinquecostatus, R. melanochaetus, R. cuspidatus and R. panzeri. The digestion of the ITS2 PCR product with TaqI allowed the discrimination of these latter two species. This molecular identification key ensures reliable results and can be successfully applied not only to adults, but also to the nymphs feeding on the roots. The identification of the nymphs (i) extends the collection period of these monovoltine species to the whole year (adults are present for a short summer period) and (ii) allows the unambiguous identification of their actual host plants because nymphs are steady on the root system while adults tend to disperse onto other plants. Fast and reliable identification of the Reptalus species provides useful help in monitoring activities and, therefore, in designing rational control strategies to protect crops from phytoplasma infection. Copyright © 2010 Cambridge University Press. Source

Fabre A.,French National Institute for Agricultural Research | Balakishiyeva G.,French National Institute for Agricultural Research | Balakishiyeva G.,Azerbaijan Academy of Sciences | Ember I.,Fitolab Plant Pest Diagnostic and Advisory Ltd. | And 7 more authors.
Bulletin of Insectology | Year: 2011

The antigenic membrane protein of stolbur phytoplasma has been cloned and characterized. The expression of StAMP in Escherichia coli produced a 16 kDa peptide recognized by an anti-stolbur monoclonal antibody. Stamp is submitted to a positive diversifying selection pressure (Fabre et al., 2011). The genetic diversity of stamp was evaluated among a collection of stolbur phytoplasma strains representative of the tuf and secY genetic diversity of stolbur phytoplasmas in the Euro-Mediterranean basin. Most of the French, Italian and Croatian strains clustered on the same phylogenetic branch (tuf-type b cluster I). A second branch of the phylogenetic tree corresponded to strains of central and Eastern Europe (tuf-type b cluster II), while a third branch grouped strains of the east of the Mediterranean basin (Greece, Serbia, Lebanon, and Azerbaijan). Strains of the tuf-type a genotype clustered together in an independent monophyletic branch of the stamp phylogenetic tree. In conclusion, stamp variability seems to be correlated to geographical origin in the case of the tuf-type b strains. Source

Camerota C.,University of Turin | Raddadi N.,University of Bologna | Pizzinat A.,University of Turin | Gonella E.,University of Turin | And 9 more authors.
Phytoparasitica | Year: 2012

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium 'Candidatus Liberibacter europaeus' was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of 'Ca. Phytoplasma pyri'. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that 'Ca. Liberibacter europaeus' is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with 'Ca. Phytoplasma' spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. 'Ca. Liberibacter europaeus' was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of 'Ca. Liberibacter europaeus' in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them. © 2012 Springer Science + Business Media B.V. Source

Acs Z.,Fitolab Plant Pest Diagnostic and Advisory Ltd. | Jovic J.,Institute for Plant Protection and Environment | Ember I.,Fitolab Plant Pest Diagnostic and Advisory Ltd. | Cvrkovic T.,Institute for Plant Protection and Environment | And 5 more authors.
Bulletin of Insectology | Year: 2011

During 2010, several maize production areas in Hungary were surveyed for the occurrence of maize redness (MR) disease symptoms associated with stolbur phytoplasma, as well as for the presence of the known vector of the disease, a planthopper Reptalus panzeri (Low). Incidence of maize plants with symptoms of reddening was low in all surveyed areas. Altogether, 25 symptomatic maize plants were collected at 9 localities and tested for phytoplasma presence. In addition, from one locality specimens of cixiids R. panzeri and Hyalesthes obsoletus Signoret were collected and PCR analyzed. Presence of stolbur phytoplasma in MR symptomatic maize plants and stolbur-infected R. panzeri was identified at the single locality Monorierdo{double acute} in central Hungary. This finding represents the first report of MR presence in Hungary. Source

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