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The European lantern fly, Dictyophara europaea, is an alternative vector of the Flavescence dorée phytoplasma (FDp) disease of grapevine in European vineyards, enabling infection initiation from wild reservoir compartment ( Clematis vitalba). Heretofore recorded rate of D. europaea FDp-infection has been very low (3%), making it less epidemiologically significant than would be expected based on reservoir plant infection rate (30%). In this study we present findings on a heavily FDp-infected D. europaea population (>60%), on the natural Wolbachia infection of populations with low FDp-infection rates (DeWo+) and on Wolbachia absence in highly FDp-infected population (DeWo−). We examine several possible causes underlying the differences in vector infection rates: (a) population genetic characteristics of D. europaea and correlation with Wolbachia strain wEur natural infections, (b) Wolbachia effects on fitness components of DeWo+ laboratory colony and (c) rate of reservoir plant FDp-infection and differences in FDp genotypes harboured by low and highly infected vector populations. The vector genetic diversity level was found to be lower in DeWo+ than in uninfected individuals and to exhibit a different evolution of fixed haplotypes. All DeWo+ populations were infected with the same strain of wEur. The FDp was found to be genetically diversified (five genotypes) but had no relation to infection rates. We did not find evidence of fitness upgrades with regard to Wolbachia infection status. Although more experimentation is needed, it seems that Wolbachia confers protection against FDp or is in competition with FDp according to the observed correlations: low FDp-infected vector populations are infected with Wolbachia and vice versa. [ABSTRACT FROM AUTHOR]

Elm yellows phytoplasmas (EY) belonging to the 16SrV-A subgroup were recently proposed as a new candidate species ' Candidatus Phytoplasma ulmi'. These pathogens infect elm trees, causing leaf yellowing and premature drying. In this study, 25 isolates originating from localities in northeast, east and southwest Serbia were characterized by means of RFLP analysis and DNA sequencing of four genomic loci: 16S rRNA, ribosomal protein rpl22- rps3, secY and map. In total, five different genotypes were identified based on collective sequencing of all four genes. Four of these genotypes showed significant nucleotide changes compared with the EY1 reference strain. Phylogeny based on parsimony analyses of ribosomal protein, secY and map genetic loci indicated a single monophyletic origin of EY1 and the new ' Ca. Phytoplasma ulmi' strains. Unlike phylogenetic clustering, DNA sequence comparison of EY1 and the novel strains revealed mutations in oligonucleotide signature sequences for all three genes (16S, rpl22- rps3 and secY) used for the characterization and assignment of 16SrV-A phytoplasmas to the ' Ca. Phytoplasma ulmi' species in the original description. Based on their high degree of genetic variability, the Serbian strains were assigned to four different subtypes of ' Ca. Phytoplasma ulmi' (EY-S1, EY-S2, EY-S3 and EY-S4). New diagnostic enzymes for practical use in ' Ca. Phytoplasma ulmi' identification are proposed for the 16S rRNA, ribosomal protein and secY genes. The implications of genetic variability within signature sequences for taxonomy and identification of ' Ca. Phytoplasma' species, as well as the importance of geographic variability and number of strains characterized for species description, are discussed. [ABSTRACT FROM AUTHOR]

The article focuses on Alder yellows (AldY) phytoplasma as a pathogen for common alder (Alnus glutinosa) and grey alder (Alnus incana) in Serbia. Alder yellows phytoplasma is related to the Flavascence dorée ave(FD) phytoplasma, a quarantine pathogen. The countries where alders are frequently infected with AldY phytoplasma are presented, as well as the symptoms exhibited on the plants which include yellowing, small leaves, and reduced foliage. Infected plants sometimes show no symptoms. A study of alders found in Veliko Gradi¡te in Serbia showing some of these symptoms, along with six symptomless controls is presented. Findings and methodology of the study is also discussed.