39 research outputs found
Role of the major antigenic membrane protein in phytoplasma transmission by two insect vector species
Optimization of abdominal microinjection parameters. Description of parameter optimizations for abdominal microinjection experiments. (PDF 56Â kb
Bacteriophage-Host Association in the Phytoplasma Insect Vector Euscelidius variegatus
Insect vectors transmit viruses and bacteria that can cause severe diseases in plants and economic losses due to a decrease in crop production. Insect vectors, like all other organisms, are colonized by a community of various microorganisms, which can influence their physiology, ecology, evolution, and also their competence as vectors. The important ecological meaning of bacteriophages in various ecosystems and their role in microbial communities has emerged in the past decade. However, only a few phages have been described so far in insect microbiomes. The leafhopper Euscelidius variegatus is a laboratory vector of the phytoplasma causing Flavescence dorée, a severe grapevine disease that threatens viticulture in Europe. Here, the presence of a temperate bacteriophage in E. variegatus (named Euscelidius variegatus phage 1, EVP-1) was revealed through both insect transcriptome analyses and electron microscopic observations. The bacterial host was isolated in axenic culture and identified as the bacterial endosymbiont of E. variegatus (BEV), recently assigned to the genus Candidatus Symbiopectobacterium. BEV harbors multiple prophages that become active in culture, suggesting that different environments can trigger different mechanisms, finely regulating the interactions among phages. Understanding the complex relationships within insect vector microbiomes may help in revealing possible microbe influences on pathogen transmission, and it is a crucial step toward innovative sustainable strategies for disease management in agriculture
The Major Antigenic Membrane Protein of âCandidatus Phytoplasma asterisâ Selectively Interacts with ATP Synthase and Actin of Leafhopper Vectors
Phytoplasmas, uncultivable phloem-limited phytopathogenic wall-less bacteria, represent a major threat to agriculture worldwide. They are transmitted in a persistent, propagative manner by phloem-sucking Hemipteran insects. Phytoplasma membrane proteins are in direct contact with hosts and are presumably involved in determining vector specificity. Such a role has been proposed for phytoplasma transmembrane proteins encoded by circular extrachromosomal elements, at least one of which is a plasmid. Little is known about the interactions between major phytoplasma antigenic membrane protein (Amp) and insect vector proteins. The aims of our work were to identify vector proteins interacting with Amp and to investigate their role in transmission specificity. In controlled transmission experiments, four Hemipteran species were identified as vectors of âCandidatus Phytoplasma asterisâ, the chrysanthemum yellows phytoplasmas (CYP) strain, and three others as non-vectors. Interactions between a labelled (recombinant) CYP Amp and insect proteins were analysed by far Western blots and affinity chromatography. Amp interacted specifically with a few proteins from vector species only. Among Amp-binding vector proteins, actin and both the α and ÎČ subunits of ATP synthase were identified by mass spectrometry and Western blots. Immunofluorescence confocal microscopy and Western blots of plasma membrane and mitochondrial fractions confirmed the localisation of ATP synthase, generally known as a mitochondrial protein, in plasma membranes of midgut and salivary gland cells in the vector Euscelidius variegatus. The vector-specific interaction between phytoplasma Amp and insect ATP synthase is demonstrated for the first time, and this work also supports the hypothesis that host actin is involved in the internalization and intracellular motility of phytoplasmas within their vectors. Phytoplasma Amp is hypothesized to play a crucial role in insect transmission specificity
Pest categorisation of the non-EU phytoplasmas of Cydonia Mill., Fragaria L., Malus Mill., Prunus L., Pyrus L., Ribes L., Rubus L. and Vitis L
Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of nine phytoplasmas of Cydonia Mill., Fragaria L., Malus Mill., Prunus L., Pyrus L., Ribes L., Rubus L. and Vitis L. (hereafter âhost plantsâ) known to occur only outside the EU or having a limited presence in the EU. This opinion covers the (i) reference strains of âCandidatus Phytoplasma australienseâ, âCa. P. fraxiniâ, âCa. P. hispanicumâ, âCa. P. trifoliiâ, âCa. P. ziziphiâ, (ii) related strains infecting the host plants of âCa. P. aurantifoliaâ, âCa. P. pruniâ, and âCa. P. pyriâ, and (iii) an unclassified phytoplasma causing Buckland valley grapevine yellows. Phytoplasmas can be detected by available methods and are efficiently transmitted by vegetative propagation, with plants for planting acting as a major entry pathway and a longâdistance spread mechanism. Phytoplasmas are also transmitted in a persistent and propagative manner by some insect families of the Fulgoromorpha, Cicadomorpha and Sternorrhyncha (order Hemiptera). No transovarial, pollen or seed transmission has been reported. The natural host range of the categorised phytoplasmas varies from one to more than 90 plant species, thus increasing the possible entry pathways. The host plants are widely cultivated in the EU. All the categorised phytoplasmas can enter and spread through the trade of host plants for planting, and by vectors. Establishment of these phytoplasmas is not expected to be limited by EU environmental conditions. The introduction of these phytoplasmas in the EU would have an economic impact. There are measures to reduce the risk of entry, establishment, spread and impact. Uncertainties result from limited information on distribution, biology and epidemiology. All the phytoplasmas categorised here meet the criteria evaluated by EFSA to qualify as potential Union quarantine pests, and they do not qualify as potential regulated nonâquarantine pests, because they are nonâEU phytoplasmas
Scaphoideus titanus up-to-the-minute: biology, ecology, and role as a vector
Native to the Nearctic region, Scaphoideus titanus Ball (Hemiptera: Cicadellidae) has become a major threat for
grapevine production after being unintentionally introduced into Europe, where it became the main vector of flavescence
dorée phytoplasma, being mainly associated with the genus Vitis. Scaphoideus titanus is a highly efficient vector of the
most important phytoplasma affecting grapevine. For this reason, compulsory insecticide treatments have been introduced
against this pest in many European countries. Moreover, the continuous expansion of its geographical distribution makes
this leafhopper a serious threat for several non-European Countries. In this article, we review the current knowledge about
its taxonomy, morphology, biology, ecology, and its role as a vector. Finally, we point out the main challenges for research
aimed at reducing S. titanus and flavescence dorée expansion across Europe and avoiding spread of the disease outside the
Old World