Luciana Galetto

Luciana Galetto
Italian National Research Council | CNR · Institute for Sustainable Plant Protection

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58
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Introduction
Skills and Expertise

Publications

Publications (58)
Article
Scaphoideus titanus (Ball) is a Nearctic leafhopper (Cicadellidae: Deltocephalinae), monophagous on Vitis spp., naturalized in European vineyards since the 20th century. Following its introduction and establishment in Europe, S. titanus became the main vector of Flavescence dorée phytoplasma (FDp) to grapevine. FDp causes heavy economic losses to v...
Article
Full-text available
Phytoplasmas are insect-borne pathogenic bacteria that cause major economic losses to several crops worldwide. The dynamic microbial community associated with insect vectors influences several aspects of their biology, including their vector competence for pathogens. Unraveling the diversity of the microbiome of phytoplasma insect vectors is gainin...
Article
Full-text available
Scaphoideus titanus (Hemiptera: Cicadellidae) is the natural vector of Flavescence dorée phytoplasma, a quarantine pest of grapevine with severe impact on European viticulture. RNA interference (RNAi) machinery components are present in S. titanus transcriptome and injection of ATP synthase β dsRNAs into adults caused gene silencing, starting three...
Article
Full-text available
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 importan...
Article
Full-text available
Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of four phytoplasmas of tuber-forming Solanum spp. known to occur only outside the EU or having a limited presence in the EU. The only tuber-forming species of Solanum reported to be phytoplasma infected is S. tuberosum. This opinion cov...
Article
Full-text available
Following a request from the European Commission, the EFSA Panel on Plant Health prepared a list of non-EU phytoplasmas of tuber-forming Solanum spp. A systematic literature review and search of databases identified 12 phytoplasmas infecting S. tuberosum. These phytoplasmas were assigned to three categories. The first group (a) consists of seven no...
Article
Full-text available
Flavescence dorée phytoplasmas (FDp, 16SrV-C and -D) are plant pathogenic non-cultivable bacteria associated with a severe grapevine disease. The incidence of the two reference strains on cultivated grapevines is unbalanced, and mixed infections are rare. To investigate the interaction between the two strains, Catharanthus roseus plants were graft-...
Article
Full-text available
The leafhopper Euscelidius variegatus is a natural vector of the chrysanthemum yellows phytoplasma (CYp) and a laboratory vector of the Flavescence dorée phytoplasma (FDp). Previous studies indicated a crucial role for insect ATP synthase α and β subunits during phytoplasma infection of the vector species. Gene silencing of ATP synthase β was obtai...
Preprint
Full-text available
The leafhopper Euscelidius variegatus is a natural vector of the chrysanthemum yellows phytoplasma (CYp) and a laboratory vector of the Flavescence dorée phytoplasma (FDp). Previous studies indicated a crucial role for insect ATP synthase α and β subunits during phytoplasma infection of the vector species. Gene silencing of ATP synthase β was obtai...
Article
Full-text available
Flavescence dorée (FD) is a quarantine grapevine disease caused by a phytoplasma transmitted by the leafhopper Scaphoideus titanus Ball. FD management relies on compulsory insecticide treatments, roguing of infected plants, and substitution with certified material. Some grapevine cultivars show a spontaneous remission of symptoms (recovery). To det...
Article
Virus-based biocontrol technologies represent sustainable alternatives to pesticides and insecticides. Phytoplasmas are prokaryotic plant pathogens causing severe losses to crops worldwide. Novel approaches are needed since insecticides against their insect vectors and rogueing of infected plants are the only available strategies to counteract phyt...
Preprint
Full-text available
Virus-based biocontrol technologies are gaining attention as sustainable alternatives to pesticides and insecticides. Phytoplasmas are prokaryotic plant pathogens causing severe losses to crops worldwide. Novel approaches are needed since insecticide treatments against their insect vectors and rogueing of infected plants are the only available stra...
Article
Full-text available
The leafhopper Scaphoideus titanus is the primary vector of Flavescence dorée phytoplasma (FDp) in European vineyards. Flavescence dorée is one of the most severely damaging diseases of Vitis vinifera and, consequently, a major threat to grape and wine production in several European countries. Control measures are compulsory, but they mainly involv...
Article
Full-text available
Abstract 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 “host plants”) known to occur only outside the EU or having a limited presence in the EU. This opin...
Article
Full-text available
Abstract Following a request from the European Commission, the EFSA Panel on Plant Health prepared a list of non‐EU phytoplasmas of Cydonia Mill., Fragaria L., Malus Mill., Prunus L., Pyrus L., Ribes L., Rubus L. and Vitis L. A systematic literature review and search of databases identified 27 phytoplasmas infecting one or more of the host genera u...
Chapter
Phytoplasmas are wall-less prokaryotes, associated with hundreds of severe crop diseases worldwide. They inhabit phloem elements and are transmitted by insects of a few hemipteran families. In absence of a cell wall, phytoplasma membrane proteins are in direct contact with insect and plant hosts. The most abundant on their pathogen cells are the im...
Article
Aims: In this study, binding between the immunodominant membrane protein Imp of the 16SrV-D phytoplasma associated with Flavescence dorée disease (FD-Dp) and insect proteins of vectors and non-vectors of FD-Dp was tested. Methods and results: Six Auchenorrhyncha species, from distantly related groups were selected: Scaphoideus titanus, Euscelidi...
Article
Ricania speculum is an Asian planthopper that was accidentally imported into Europe from the Far East. The planthopper was first observed in Italy in 2009 (Genoa province, Liguria) and is now considered established. The current range of R. speculum in Italy includes Liguria, Tuscany, Veneto, Piedmont and Latium. Ricania speculum is polyphagous and...
Chapter
To visualize phytoplasmas at early stages of vector infection, an immunofluorescence assay was developed. The chapter provides experimental details on dissection of salivary glands, incubation of the dissected organs with phytoplasma suspension, fixation, embedding, sectioning, labeling, and final visualization with confocal microscopy. All the pro...
Article
The involvement of immunodominant membrane protein Imp of 16SrV-D phytoplasma (16SrV-Dp) in the interaction with insect proteins were investigated. The his-tagged Imp protein and a rabbit polyclonal antibody was produced and used in Far-Western dot Blot (FWdB) assays. Total Native Proteins were extracted from batches of six insect species (Scaphoid...
Article
The biological bases of recovery of two grapevine cultivars, Nebbiolo and Barbera, showing different susceptibility and recovery ability to “flavescence dorée” (FD) phytoplasma infection were investigated. The expression over one vegetative season, in FD-recovered and healthy grapevines, of 18 genes involved in defence, hydrogen peroxide and hormon...
Article
BACKGROUND: RNA interference (RNAi) techniques have emerged as powerful tools to develop novel management strategies for the control of insect pests. The leafhopper Euscelidius variegatus is a natural vector of chrysanthemum yellows phytoplasma and a laboratory vector of flavescence dorée phytoplasma. Phytoplasmas are insect-borne bacterial plant p...
Article
Many aspects of plant diseases caused by phytoplasmas are still unknown, as these pathogens are phloem restricted, uncultivable wall-less bacteria and must be studied always in association with their host. Phytoplasma transcripts are strongly underrepresented within host tissues and this poses problems for gene expression analyses. In this study, a...
Article
Phytoplasmas are plant pathogenic bacteria transmitted by hemipteran insects. The leafhopper Euscelidius variegatus is a natural vector of chrysanthemum yellows phytoplasma (CYp) and a laboratory vector of Flavescence dorée phytoplasma (FDp). The two phytoplasmas induce different effects on this species: CYp slightly improves, while FDp negatively...
Poster
Philaenus spumariusis the vector of the CoDiRO strain (subsp.pauca) of Xylella fastidiosa in the Apulian olive orchards. Dispersal capability of the vector is of capital importance to predictfuture spreading of the pathogen, thus representing a research priority. Mark-release-recapture (MRR) is the method of choice to study movement of vector insec...
Article
Molecular mechanisms underlying phytoplasma interactions with host plants are largely unknown. In this study attempts were made to identify effectors of three phytoplasma strains related to ‘Ca. P. aurantifolia’, crotalaria phyllody (CrP), faba bean phyllody (FBP), and witches’ broom disease of lime (WBDL), using information from draft genome of pe...
Article
Full-text available
The leafhopper Euscelidius variegatus is a natural vector of chrysanthemum yellows phytoplasma (CY) and an efficient vector of flavescence dorée phytoplasma (FD) under laboratory conditions. During a transcriptome sequencing (RNA-seq) project aimed at investigating the interactions between the insect and the two phytoplasmas, a 10,616-nucleotide-lo...
Article
Analyses of space-time statistical features of a flavescence dorée (FD) epidemic in Vitis vinifera plants are presented. FD spread was surveyed from 2011 to 2015 in a vineyard of 17,500 m² surface area in the Piemonte region, Italy; count and position of symptomatic plants were used to test the hypothesis of epidemic Complete Spatial Randomness and...
Article
Full-text available
Flavescence dorée (FD) is a threat for wine production in the vineyard landscape of Piemonte, Langhe-Roero and Monferrato, Italy. Spread of the disease is dependent on complex interactions between insect, plant and phytoplasma. In the Piemonte region, wine production is based on local cultivars. The role of six local grapevine varieties as a source...
Article
Background: Acibenzolar-S-methyl (BTH), a functional analog of Salicylic Acid (SA), is known to elicit a systemic resistance across a broad range of plant-pathogen interactions but, so far, it was not tested against Flavescence dorée (FDP), one of the most devastating grapevine diseases. Aims of this work were to evaluate the activity of BTH in pr...
Article
Full-text available
Flavescence dorée is an epidemic yellows disease of grapevine, caused by a phytoplasma (FDP), for which there is currently no cure. We assessed whether the endophyte Pseudomonas migulae 8R6, able to synthesize 1-aminocyclopropane-1-carboxylate (ACC) deaminase, can limit the phytoplasma-induced damages in periwinkle, a model plant hosting FDP. Plant...
Article
Full-text available
Background Phytoplasmas are bacterial plant pathogens (class Mollicutes), transmitted by phloem feeding leafhoppers, planthoppers and psyllids in a persistent/propagative manner. Transmission of phytoplasmas is under the control of behavioral, environmental and geographical factors, but molecular interactions between membrane proteins of phytoplasm...
Article
Full-text available
To highlight different transcriptional behaviors of the phytoplasma in the plant and animal host, expression of 14 genes of 'Candidatus Phytoplasma asteris', chrysanthemum yellows strain, was investigated at different times following the infection of a plant host (Arabidopsis thaliana) and two insect vector species (Macrosteles quadripunctulatus an...
Article
Full-text available
The phytoplasma-borne disease flavescence doree is still a threat to European viticulture, despite mandatory control measures and prophylaxis against the leafhopper vector. Given the economic importance of grapevine, it is essential to find alternative strategies to contain the spread, in order to possibly reduce the current use of harmful insectic...
Article
Flavescence doree (FD) is one of the most economically important grapevine diseases in Southern Europe, and it is associated with phytoplasmas, phloemlimited wall-less bacteria. Recovery from disease naturally occurs in infected grapevines during the following seasons after infection. The capability of the leafhopper vector Scaphoideus titanus to a...
Article
Full-text available
A set of experiments was carried out to characterize how temperature affects the spread of chrysanthemum yellows phytoplasma (CYP), a strain of Candidatus Phytoplasma asteris, in Chrysanthemum carinatum plants transmitted by the Macrosteles quadripunctulatus leafhopper. Experiments provided data on CYP latency period in insect and plant host, M. qu...
Article
Phytoplasmas are wall-less bacteria associated with many plant diseases of wild and cultivated plants, transmitted by hemipteran insects. In nature, vectors can acquire more than one phytoplasma by feeding on multiple-infected source plants or sequentially on plants infected by different phytoplasmas. The acquisition of multiple phytoplasmas may le...
Conference Paper
Full-text available
Phytoplasmas are phloem-limited wall-less bacteria transmitted by phloem-feeder leafhoppers, planthoppers, and psyllids (Hemiptera). Flavescence dorée (FD) is the most important grapevine disease in Southern Europe. It is associated with phytoplasmas of the 16Sr-V ribosomal group, and is specifically transmitted, under field conditions, by the leaf...
Article
Flavescence dorée phytoplasma (FDP) titre in two red grapevine cultivars, Barbera and Nebbiolo, was measured over the vegetative seasons of two consecutive years in two vineyards of the Piemonte Region (northwestern Italy), with a double absolute quantification of FDP cells and grapevine DNA in real‐time PCR. The relationships of pathogen concentra...
Article
Full-text available
Phytoplasmas are phloem-limited phytopathogenic wall-less bacteria and represent a major threat to agriculture worldwide. They are transmitted in a persistent, propagative manner by phloem-sucking Hemipteran insects. For gene expression studies based on mRNA quantification by RT-qPCR, stability of housekeeping genes is crucial. The aim of this stud...
Article
The study of phytoplasma membrane protein interactions with host cell proteins is crucial to understand the life cycle of these unculturable microorganisms within their hosts. A step-by-step protocol for the heterologous expression of phytoplasma membrane proteins in Escherichia coli is described, together with a procedure to purify a suitable quan...
Article
The immunodominant membrane protein Imp of several phytoplasmas within the ‘Candidatus Phytoplasma aurantifolia’ (16Sr-II) group was investigated. Eighteen isolates from Iran (11), East Asia (5), Africa (1) and Australia (1) clustered into three phylogenetic subgroups (A, B and C) based on the 16S rDNA and imp genes, regardless of geographic origin...
Article
Full-text available
Multiplication patterns of two phytoplasmas, chrysanthemum yellows and 'flavescence dorée' were characterized over time in insect vectors and plant hosts under different climatic (temperature, T, and CO 2) conditions. Acquisition and transmission experi-ments were run in parallel in two phytotrons (P1 and P2). Euscelidius variegatus and daisy were...
Article
Lime witches' broom phytoplasma (16SrII, LWB) causes major losses to lime cultivation in Iran. The role of its immunodominant membrane protein (IMP) in the specific interaction with vector proteins was addressed. The carboxy terminal moiety of LWB IMP, coding the extracellular part of the protein, was expressed (LWB f Delta IMP) as a tool to study...
Article
Full-text available
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....
Article
Phytoplasmas are phloem-restricted plant pathogens transmitted by leafhoppers, planthoppers, and psyllids (Hemiptera). Most known phytoplasma vectors belong to the Cicadellidae, but many are still unknown. Within this family, Empoasca spp. (Typhlocybinae) have tested positive for the presence of some phytoplasmas, and phytoplasma transmission has b...
Article
Phytoplasmas are plant-pathogenic Mollicutes transmitted by leafhoppers, planthoppers, and psyllids in a persistent propagative manner. Chrysanthemum yellows phytoplasma (CY) is a member of ‘Candidatus Phytoplasma asteris’, 16Sr-IB, and is transmitted by at least three leafhopper species, Macrosteles quadripunctulatus Kirschbaum, Euscelidius varieg...
Article
Full-text available
To characterize potentially important surface-exposed proteins of the phytoplasma causing chrysanthemum yellows (CY), new primers were designed based on the conserved regions of 3 membrane protein genes of the completely sequenced onion yellows and aster yellows witches' broom phytoplasmas and were used to amplify CY DNA. The CY genes secY, amp, an...
Article
Full-text available
The titre of chrysanthemum yellows phytoplasma (CYp, 'Candidatus Phytoplasma asteris') in the three vector species Euscelis incisus, Euscelidius variegatus and Macrosteles quadripunctulatus has been measured following controlled acquisition from in-fected source plants. Phytoplasma DNA was quantified in relation to insect DNA (genome units, GU, of...
Article
Full-text available
Three genes encoding membrane proteins of chrysanthemum yellows (CY) phytoplasma were cloned and sequenced: SecY, Amp and ArtI encoding the protein translocase subunit SecY, the antigenic membrane protein Amp and the arginine transporter ArtI, respectively. Alignments of CY-specific SecY sequences with the corresponding genes of other phytoplasmas...
Article
The titer of chrysanthemum yellows phytoplasma (CYP, "Candidatus Phytoplasma asteris") in the three vector species Euscelis incisus Kirschbaum, Euscelidius variegatus Kirschbaum, and Macrosteles quadripunctulatus Kirschbaum (Homoptera: Cicadellidae) was measured after controlled acquisition from infected Chrysanthemum carinatum (Schousboe) (daisy)...
Article
Three real-time PCR–based assays for the specific diagnosis of flavescence dorée (FD), bois noir (BN) and apple proliferation (AP) phytoplasmas and a universal one for the detection of phytoplasmas belonging to groups 16Sr-V, 16Sr-X and 16Sr-XII have been developed. Ribosomal-based primers CYS2Fw/Rv and TaqMan probe CYS2 were used for universal dia...

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Project (1)
Project
Rhizospheric bacteria and arbuscular mycorrhizal fungi have been selected and inoculated in model plants and in Vitis vinifera, both in the lab and in the field. Symptom evaluation of phytoplasmoses, especially"flavescence dorèè" is periodically performed, by visual and molecular analyses.