scholarly journals Variable Membrane Protein A of Flavescence Dorée Phytoplasma Binds the Midgut Perimicrovillar Membrane ofEuscelidius variegatusand Promotes Adhesion to Its Epithelial Cells

2018 ◽  
Vol 84 (8) ◽  
pp. e02487-17 ◽  
Author(s):  
Nathalie Arricau-Bouvery ◽  
Sybille Duret ◽  
Marie-Pierre Dubrana ◽  
Brigitte Batailler ◽  
Delphine Desqué ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Salivary Glands ◽  
Plant Pathogens ◽  
Insect Cells ◽  
Wild Plants ◽  
Insect Vector ◽  
Plant Host ◽  
Content Type ◽  
Flavescence Dorée ◽  
Fluorescent Beads

ABSTRACTPhytoplasmas are uncultivated plant pathogens and cell wall-less bacteria and are transmitted from plant to plant by hemipteran insects. The phytoplasma's circulative propagative cycle in insects requires the crossing of the midgut and salivary glands, and primary adhesion to cells is an initial step toward the invasion process. The flavescence dorée (FD) phytoplasma possesses a set of variable membrane proteins (Vmps) exposed on its surface, and this pathogen is suspected to interact with insect cells. The results showed that VmpA is expressed by the flavescence dorée phytoplasma present in the midgut and salivary glands. Phytoplasmas cannot be cultivated at present, and no mutant can be produced to investigate the putative role of Vmps in the adhesion of phytoplasma to insect cells. To overcome this difficulty, we engineered theSpiroplasma citrimutant G/6, which lacks the ScARP adhesins, for VmpA expression and used VmpA-coated fluorescent beads to determine if VmpA acts as an adhesin inex vivoadhesion assays andin vivoingestion assays. VmpA specifically interacted withEuscelidiusvariegatusinsect cells in culture and promoted the retention of VmpA-coated beads to the midgut ofE. variegatus. In this latest case, VmpA-coated fluorescent beads were localized and embedded in the perimicrovillar membrane of the insect midgut. Thus, VmpA functions as an adhesin that could be essential in the colonization of the insect by the FD phytoplasmas.IMPORTANCEPhytoplasmas infect a wide variety of plants, ranging from wild plants to cultivated species, and are transmitted by different leafhoppers, planthoppers, and psyllids. The specificity of the phytoplasma-insect vector interaction has a major impact on the phytoplasma plant host range. As entry into insect cells is an obligate process for phytoplasma transmission, the bacterial adhesion to insect cells is a key step. Thus, studying surface-exposed proteins of phytoplasma will help to identify the adhesins implicated in the specific recognition of insect vectors. In this study, it is shown that the membrane protein VmpA of the flavescence dorée (FD) phytoplasma acts as an adhesin that is able to interact with cells ofEuscelidiusvariegatus, the experimental vector of the FD phytoplasma.

scholarly journals The Bacterium Pantoea stewartii Uses Two Different Type III Secretion Systems To Colonize Its Plant Host and Insect Vector

2012 ◽  
Vol 78 (17) ◽  
pp. 6327-6336 ◽  
Author(s):  
Valdir R. Correa ◽  
Doris R. Majerczak ◽  
El-Desouky Ammar ◽  
Massimo Merighi ◽  
Richard C. Pratt ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Flea Beetle ◽  
Insect Vector ◽  
Secretion Systems ◽  
Plant Host ◽  
Content Type ◽  
Type Iii ◽  
Pantoea Stewartii ◽  
Type Iii Secretion Systems ◽  
Animal Pathogens

ABSTRACTPlant- and animal-pathogenic bacteria utilize phylogenetically distinct type III secretion systems (T3SS) that produce needle-like injectisomes or pili for the delivery of effector proteins into host cells.Pantoea stewartiisubsp.stewartii(herein referred to asP. stewartii), the causative agent of Stewart's bacterial wilt and leaf blight of maize, carries phylogenetically distinct T3SSs. In addition to an Hrc-Hrp T3SS, known to be essential for maize pathogenesis,P. stewartiihas a second T3SS (Pantoeasecretion island 2 [PSI-2]) that is required for persistence in its flea beetle vector,Chaetocnema pulicaria(Melsh). PSI-2 belongs to the Inv-Mxi-Spa T3SS family, typically found in animal pathogens. Mutagenesis of the PSI-2psaNgene, which encodes an ATPase essential for secretion of T3SS effectors by the injectisome, greatly reduces both the persistence ofP. stewartiiin flea beetle guts and the beetle's ability to transmitP. stewartiito maize. Ectopic expression of thepsaNgene complements these phenotypes. In addition, the PSI-2psaNgene is not required forP. stewartiipathogenesis of maize and is transcriptionally upregulated in insects compared to maize tissues. Thus, the Hrp and PSI-2 T3SSs play different roles in the life cycle ofP. stewartiias it alternates between its insect vector and plant host.

scholarly journals Decreasing Global Transcript Levels over Time Suggest that Phytoplasma Cells Enter Stationary Phase during Plant and Insect Colonization

2015 ◽  
Vol 81 (7) ◽  
pp. 2591-2602 ◽  
Author(s):  
D. Pacifico ◽  
L. Galetto ◽  
M. Rashidi ◽  
S. Abbà ◽  
S. Palmano ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Target Genes ◽  
Secreted Proteins ◽  
Healthy Plant ◽  
Insect Vector ◽  
Plant Host ◽  
Term Survival ◽  
Transcript Levels ◽  
Content Type ◽  
Macrosteles Quadripunctulatus

ABSTRACTTo highlight different transcriptional behaviors of the phytoplasma in the plant and animal host, expression of 14 genes of “CandidatusPhytoplasma asteris,” chrysanthemum yellows strain, was investigated at different times following the infection of a plant host (Arabidopsis thaliana) and two insect vector species (Macrosteles quadripunctulatusandEuscelidius variegatus). Target genes were selected among those encoding antigenic membrane proteins, membrane transporters, secreted proteins, and general enzymes. Transcripts were detected for all analyzed genes in the three hosts; in particular, those encoding the antigenic membrane protein Amp, elements of the mechanosensitive channel, and two of the four secreted proteins (SAP54 and TENGU) were highly accumulated, suggesting that they play important roles in phytoplasma physiology during the infection cycle. Most transcripts were present at higher abundance in the plant host than in the insect hosts. Generally, transcript levels of the selected genes decreased significantly during infection ofA. thalianaandM. quadripunctulatusbut were more constant inE. variegatus. Such decreases may be explained by the fact that only a fraction of the phytoplasma population was transcribing, while the remaining part was aging to a stationary phase. This strategy might improve long-term survival, thereby increasing the likelihood that the pathogen may be acquired by a vector and/or inoculated to a healthy plant.

Made for each other: Vector-pathogen interfaces in the Huanglongbing pathosystem

2021 ◽  
Author(s):  
Nabil Killiny
Keyword(s):  
Plant Pathogens ◽  
Management Strategies ◽  
Tca Cycle ◽  
Detoxification Enzymes ◽  
Insect Vector ◽  
Insect Vectors ◽  
Plant Host ◽  
Atp Production ◽  
Molecular Features ◽  
Animal Pathogens

Citrus greening, or Huanglongbing (HLB), currently is the most destructive disease of citrus. HLB disease is putatively caused by the phloem-restricted α-proteobacterium, ‛Candidatus Liberibacter asiaticus’. This bacterium is primarily transmitted by the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae). Most animal pathogens are considered pathogenic to their insect vectors, whereas the relationships between plant pathogens and their insect vectors are variable. Lately, the relationship of ‛Ca. L. asiaticus’ with its insect vector, D. citri was well investigated at the molecular, biochemical, and biological levels in many studies. Herein, the findings concerning this relationship are discussed and molecular features of the acquisition of ‛Ca. L. asiaticus’ from the plant host and its growth and circulation within D. citri, as well as its transmission to plants, are presented. In addition, the effects of ‛Ca. L. asiaticus’ on the energy metabolism (respiration, TCA cycle, the ATP production), metabolic pathways, immune system, endosymbionts, and detoxification enzymes of D. citri are discussed together with other impacts such as shorter lifespan, altered feeding behavior, and higher fecundity. Overall, although ‛Ca. L. asiaticus’ has significant negative effects on its insect vector, it increases its vector fitness, indicating that it develops a mutualistic relationship with its vector. This review will help in understanding the specific interactions between ‛Ca. L. asiaticus’ and its psyllid vector in order to design innovative management strategies.

scholarly journals Factors Affecting the Initial Adhesion and Retention of the Plant Pathogen Xylella fastidiosa in the Foregut of an Insect Vector

2013 ◽  
Vol 80 (1) ◽  
pp. 420-426 ◽  
Author(s):  
Nabil Killiny ◽  
Rodrigo P. P. Almeida
Keyword(s):  
Galacturonic Acid ◽  
Artificial Diet ◽  
Plant Pathogens ◽  
Xylella Fastidiosa ◽  
Insect Vector ◽  
Vector Transmission ◽  
Content Type ◽  
Factors Affecting ◽  
Regulatory Systems ◽  
Initial Adhesion

ABSTRACTVector transmission of bacterial plant pathogens involves three steps: pathogen acquisition from an infected host, retention within the vector, and inoculation of cells into susceptible tissue of an uninfected plant. In this study, a combination of plant and artificial diet systems were used to determine the importance of several genes on the initial adhesion and retention of the bacteriumXylella fastidiosato an efficient insect vector. Mutant strains included fimbrial (fimAandpilB) and afimbrial (hxfAandhxfB) adhesins and three loci involved in regulatory systems (rpfF,rpfC, andcgsA). Transmission assays with variable retention time indicated that HxfA and HxfB were primarily important for early adhesion to vectors, while FimA was necessary for both adhesion and retention. The long pilus protein PilB was not deficient in initial adhesion but may be important for retention. Genes upregulated under the control ofrpfFare important for both initial adhesion and retention, as transmission rates of this mutant strain were initially low and decreased over time, while disruption ofrpfCandcgsAyielded trends similar to that shown by the wild-type control. Because induction of anX. fastidiosatransmissible state requires pectin, a series of experiments were used to test the roles of a polygalacturonase (pglA) and the pectin and galacturonic acid carbohydrates on the transmission ofX. fastidiosa. Results show that galacturonic acid, or PglA activity breaking pectin into its major subunit (galacturonic acid), is required forX. fastidiosavector transmission using an artificial diet system. This study shows that early adhesion and retention ofX. fastidiosaare mediated by different factors. It also illustrates that the interpretation of results of vector transmission experiments, in the context of vector-pathogen interaction studies, is highly dependent on experimental design.

scholarly journals Filamentous Structures Induced by a Phytoreovirus Mediate Viral Release from Salivary Glands in Its Insect Vector

2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Qianzhuo Mao ◽  
Zhenfeng Liao ◽  
Jiajia Li ◽  
Yuyan Liu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Viral Transmission ◽  
Insect Vector ◽  
Insect Vectors ◽  
Viral Control ◽  
Content Type ◽  
Viral Release ◽  
Persistent Viruses ◽  
Membrane Barrier

ABSTRACT Numerous viral pathogens are persistently transmitted by insect vectors and cause agricultural or health problems. These viruses circulate in the vector body, enter the salivary gland, and then are released into the apical plasmalemma-lined cavities, where saliva is stored. The cavity plasmalemma of vector salivary glands thus represents the last membrane barrier for viral transmission. Here, we report a novel mechanism used by a persistent virus to overcome this essential barrier. We observed that the infection by rice gall dwarf virus (RGDV), a species of the genus Phytoreovirus in the family Reoviridae, induced the formation of virus-associated filaments constructed by viral nonstructural protein Pns11 within the salivary glands of its leafhopper vector, Recilia dorsalis. Such filaments attached to actin-based apical plasmalemma and induced an exocytosis-like process for viral release into vector salivary gland cavities, through a direct interaction of Pns11 of RGDV and actin of R. dorsalis. Failure of virus-induced filaments assembly by RNA interference with synthesized double-stranded RNA targeting the Pns11 gene inhibited the dissemination of RGDV into salivary cavities, preventing viral transmission by R. dorsalis. For the first time, we show that a virus can exploit virus-induced inclusion as a vehicle to pass through the apical plasmalemma into vector salivary gland cavities, thus overcoming the last membrane barrier for viral transmission by insect vectors. IMPORTANCE Understanding how persistent viruses overcome multiple tissue and membrane barriers within the insect vectors until final transmission is the key for viral disease control. The apical plasmalemma of the cavities where saliva is stored in the salivary glands is the last barrier for viral transmission by insect vectors; however, the mechanism is still poorly understood. Here we show that a virus has evolved to exploit virus-induced filaments to perform an exocytosis-like process that enables viral passage through the apical plasmalemma into salivary cavities. This mechanism could be extensively exploited by other persistent viruses to overcome salivary gland release barriers in insect vectors, opening new perspectives for viral control.

scholarly journals Vector Transmission of a Plant-Pathogenic Bacterium in the Arsenophonus Clade Sharing Ecological Traits with Facultative Insect Endosymbionts

2009 ◽  
Vol 99 (11) ◽  
pp. 1289-1296 ◽  
Author(s):  
Alberto Bressan ◽  
Olivier Sémétey ◽  
Joel Arneodo ◽  
Jeannine Lherminier ◽  
Elisabeth Boudon-Padieu
Keyword(s):  
Sugar Beet ◽  
Salivary Glands ◽  
Emerging Adults ◽  
Plant Pathogens ◽  
Average Frequency ◽  
Reproductive Organs ◽  
Insect Vector ◽  
High Concentration ◽  
Ecological Traits ◽  
Late Instar

The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the major vector of a nonculturable plant-pathogenic γ-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. Field-collected planthoppers showed a percentage of infection that averaged from 57% for early instar nymphs to near 100% for late instar nymphs and emerging adults. SBR bacterium was persistently transmitted by emerging adults. Root-feeding nymphs were able to inoculate SBR bacterium to sugar beet. The bacterium was transmitted vertically from infected parental females to their respective offspring with an average frequency of 30%. Real-time polymerase chain reaction assays on dissected planthopper internal organs revealed a high concentration of the bacterium within male and female reproductive organs and within female salivary glands. SBR-like bacteria were observed through transmission electron microscopy in the cytoplasm of different insect organs including ovaries, salivary glands, and guts with no evidence for cytological disorders. SBR bacterium seems to share common ecological traits of insect-transmitted plant pathogens and facultative insect endosymbionts suggesting it may have evolved primarily as an insect-associated bacterium.

scholarly journals O Antigen Modulates Insect Vector Acquisition of the Bacterial Plant Pathogen Xylella fastidiosa

2015 ◽  
Vol 81 (23) ◽  
pp. 8145-8154 ◽  
Author(s):  
Jeannette N. Rapicavoli ◽  
Nichola Kinsinger ◽  
Thomas M. Perring ◽  
Elaine A. Backus ◽  
Holly J. Shugart ◽  
...  
Keyword(s):  
Cell Surface ◽  
Plant Pathogen ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Xylella Fastidiosa ◽  
Insect Vector ◽  
Physiochemical Properties ◽  
Content Type ◽  
O Antigen ◽  
Bacterial Plant Pathogen

ABSTRACTHemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogenXylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment ofX. fastidiosato blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics ofX. fastidiosaadhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen.

scholarly journals Interactions between the flavescence dorée phytoplasma and its insect vector indicate lectin-type adhesion mediated by the adhesin VmpA

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathalie Arricau-Bouvery ◽  
Sybille Duret ◽  
Marie-Pierre Dubrana ◽  
Delphine Desqué ◽  
Sandrine Eveillard ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Insect Cell ◽  
Insect Cell Line ◽  
Insect Vector ◽  
Flavescence Dorée ◽  
Salivary Gland Cells ◽  
Scaphoideus Titanus ◽  
Euscelidius Variegatus ◽  
Natural Vector ◽  
Insect Gut

AbstractThe flavescence dorée phytoplasma undergoes a propagative cycle in its insect vectors by first interacting with the insect cell surfaces, primarily in the midgut lumen and subsequently in the salivary glands. Adhesion of flavescence dorée phytoplasma to insect cells is mediated by the adhesin VmpA. We hypothesize that VmpA may have lectin-like activity, similar to several adhesins of bacteria that invade the insect gut. We first demonstrated that the luminal surface of the midgut and the basal surface of the salivary gland cells of the natural vector Scaphoideus titanus and those of the experimental vector Euscelidius variegatus were differentially glycosylated. Using ELISA, inhibition and competitive adhesion assays, and protein overlay assays in the Euva-6 insect cell line, we showed that the protein VmpA binds insect proteins in a lectin-like manner. In conclusion, the results of this study indicate that N-acetylglucosamine and mannose present on the surfaces of the midgut and salivary glands serve as recognition sites for the phytoplasma adhesin VmpA.

scholarly journals Sequential production of gametes during meiosis in trypanosomes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lori Peacock ◽  
Chris Kay ◽  
Chloe Farren ◽  
Mick Bailey ◽  
Mark Carrington ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Cell Types ◽  
Tsetse Fly ◽  
Binucleate Cell ◽  
Insect Vector ◽  
Content Ratio ◽  
Different Cell Types ◽  
Meiosis I

AbstractMeiosis is a core feature of eukaryotes that occurs in all major groups, including the early diverging excavates. In this group, meiosis and production of haploid gametes have been described in the pathogenic protist, Trypanosoma brucei, and mating occurs in the salivary glands of the insect vector, the tsetse fly. Here, we searched for intermediate meiotic stages among trypanosomes from tsetse salivary glands. Many different cell types were recovered, including trypanosomes in Meiosis I and gametes. Significantly, we found trypanosomes containing three nuclei with a 1:2:1 ratio of DNA contents. Some of these cells were undergoing cytokinesis, yielding a mononucleate gamete and a binucleate cell with a nuclear DNA content ratio of 1:2. This cell subsequently produced three more gametes in two further rounds of division. Expression of the cell fusion protein HAP2 (GCS1) was not confined to gametes, but also extended to meiotic intermediates. We propose a model whereby the two nuclei resulting from Meiosis I undergo asynchronous Meiosis II divisions with sequential production of haploid gametes.

scholarly journals Skipping the Insect Vector: Plant Stolon Transmission of the Phytopathogen ‘Ca. Phlomobacter fragariae’ from the Arsenophonus Clade of Insect Endosymbionts

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 93
Author(s):  
Jessica Dittmer ◽  
Thierry Lusseau ◽  
Xavier Foissac ◽  
Franco Faoro
Keyword(s):  
Plant Pathogens ◽  
Model Systems ◽  
Insect Vector ◽  
Evolutionary Perspective ◽  
Evolutionary Transition ◽  
Strawberry Plant ◽  
Disease Symptoms ◽  
Transmission Electron ◽  
Nutrient Provisioning ◽  
Early Growth Phase

The genus Arsenophonus represents one of the most widespread clades of insect endosymbionts, including reproductive manipulators and bacteriocyte-associated primary endosymbionts. Two strains belonging to the Arsenophonus clade have been identified as insect-vectored plant pathogens of strawberry and sugar beet. The bacteria accumulate in the phloem of infected plants, ultimately causing leaf yellows and necrosis. These symbionts therefore represent excellent model systems to investigate the evolutionary transition from a purely insect-associated endosymbiont towards an insect-vectored phytopathogen. Using quantitative PCR and transmission electron microscopy, we demonstrate that ‘Candidatus Phlomobacter fragariae’, bacterial symbiont of the planthopper Cixius wagneri and the causative agent of Strawberry Marginal Chlorosis disease, can be transmitted from an infected strawberry plant to multiple daughter plants through stolons. Stolons are horizontally growing stems enabling the nutrient provisioning of daughter plants during their early growth phase. Our results show that Phlomobacter was abundant in the phloem sieve elements of stolons and was efficiently transmitted to daughter plants, which rapidly developed disease symptoms. From an evolutionary perspective, Phlomobacter is, therefore, not only able to survive within the plant after transmission by the insect vector, but can even be transmitted to new plant generations, independently from its ancestral insect host.

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