scholarly journals Infections of the Xylella fastidiosa subsp. pauca Strain “De Donno” in Alfalfa (Medicago sativa) Elicits an Overactive Immune Response

Plants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 335 ◽  
Author(s):  
Raied Abou Kubaa ◽  
Annalisa Giampetruzzi ◽  
Giuseppe Altamura ◽  
Maria Saponari ◽  
Pasquale Saldarelli
Keyword(s):  
Medicago Sativa ◽  
Xylella Fastidiosa ◽  
Plant Immunity ◽  
Hypersensitive Reaction ◽  
Infection Process ◽  
Susceptible Host ◽  
Olive Quick Decline Syndrome ◽  
Dwarf Disease ◽  
Transmembrane Transporters

Diseases caused by Xylella fastidiosa are among the most destructive for several agricultural productions. A deadly disease of olive, termed olive quick decline syndrome, is one of the most recent examples of the severe impacts caused by the introduction and spread of this bacterium in new ecosystems with favorable epidemiological conditions. Deciphering the cascade of events leading to the development of severe alterations in the susceptible host plants is a priority of several research programs investigating strategies to mitigate the detrimental impacts of the infections. However, in the case of olives, the long latent period (>1 year) makes this pathosystem not amenable for such studies. We have inoculated alfalfa (Medicago sativa) with the olive-infecting strain “De Donno” isolated from a symptomatic olive in Apulia (Italy), and we demonstrated that this highly pathogenic strain causes an overactive reaction that ends up with the necrosis of the inoculated stem, a reaction that differs from the notoriously Alfalfa Dwarf disease, caused by X. fastidiosa strains isolated from grapes and almonds. RNASeq analysis showed that major plant immunity pathways are activated, in particular, several calcium transmembrane transporters and enzymes responsible for the production of reactive oxygen species (ROS). Signs of the necrotic reaction are anticipated by the upregulation of genes responsible for plant cell death and the hypersensitive reaction. Overall the whole infection process takes four months in alfalfa, which makes this pathosystem suitable for studies involving either the plant response to the infection or the role of Xylella genes in the expression of symptoms.

scholarly journals The Xylella fastidiosa-Resistant Olive Cultivar “Leccino” Has Stable Endophytic Microbiota during the Olive Quick Decline Syndrome (OQDS)

Pathogens ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 35 ◽  
Author(s):  
Marzia Vergine ◽  
Joana B. Meyer ◽  
Massimiliano Cardinale ◽  
Erika Sabella ◽  
Martin Hartmann ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Resistance Mechanisms ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Olive Cultivar ◽  
Olive Quick Decline Syndrome ◽  
Olive Trees ◽  
Potential Interactions ◽  
Highly Virulent

Xylella fastidiosa is a highly virulent pathogen that causes Olive Quick Decline Syndrome (OQDS), which is currently devastating olive plantations in the Salento region (Apulia, Southern Italy). We explored the microbiome associated with X. fastidiosa-infected (Xf-infected) and -uninfected (Xf-uninfected) olive trees in Salento, to assess the level of dysbiosis and to get first insights into the potential role of microbial endophytes in protecting the host from the disease. The resistant cultivar “Leccino” was compared to the susceptible cultivar “Cellina di Nardò”, in order to identify microbial taxa and parameters potentially involved in resistance mechanisms. Metabarcoding of 16S rRNA genes and fungal ITS2 was used to characterize both total and endophytic microbiota in olive branches and leaves. “Cellina di Nardò” showed a drastic dysbiosis after X. fastidiosa infection, while “Leccino” (both infected and uninfected) maintained a similar microbiota. The genus Pseudomonas dominated all “Leccino” and Xf-uninfected “Cellina di Nardò” trees, whereas Ammoniphilus prevailed in Xf-infected “Cellina di Nardò”. Diversity of microbiota in Xf-uninfected “Leccino” was higher than in Xf-uninfected “Cellina di Nardò”. Several bacterial taxa specifically associated with “Leccino” showed potential interactions with X. fastidiosa. The maintenance of a healthy microbiota with higher diversity and the presence of cultivar-specific microbes might support the resistance of “Leccino” to X. fastidiosa. Such beneficial bacteria might be isolated in the future for biological treatment of the OQDS.

scholarly journals Transmission of Xylella fastidiosa Subspecies Pauca Sequence Type 53 by Different Insect Species

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 324 ◽  
Author(s):  
Vincenzo Cavalieri ◽  
Giuseppe Altamura ◽  
Giulio Fumarola ◽  
Michele di Carolo ◽  
Maria Saponari ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Severe Disease ◽  
Xylem Sap ◽  
Seasonal Abundance ◽  
Philaenus Spumarius ◽  
Olive Groves ◽  
Sap Feeding ◽  
Olive Quick Decline Syndrome ◽  
Exotic Pathogen

Diseases associated with Xylella fastidiosa have been described mostly in North and South America. However, during the last five years, widespread X. fastidiosa infections have been reported in a constrained area of the Apulia region (southern Italy), in olives trees suffering a severe disease, denoted as Olive Quick Decline Syndrome (OQDS). Because many xylem sap-feeding insects can function as vectors for the transmission of this exotic pathogen in EU, several research programs are ongoing to assess the role of candidate vectors in the spread of the infections. Initial investigations identified Philaenus spumarius (L.) as the predominant vector species in the olive orchards affected by the OQDS. Additional experiments have been carried out during 2016 and 2017 to assess the role of other species. More specifically, adults of the spittlebugs Philaenus italosignus Drosopolous and Remane, Neophilaenus campestris (Fallen) and of the planthopper Latilica tunetana (Matsumura) (Issidae) have been tested in transmission experiments to assess their ability to acquire the bacterium from infected olives and to infect different susceptible hosts (olives, almond, myrtle –leaf milkwort, periwinkle). Acquisition rates determined by testing individual insects in quantitative PCR assays, ranging from 5.6% in N. campestris to 22.2% in P. italosignus, whereas no acquisition was recorded for L. tunetana. Successful transmissions were detected in the recipient plants exposed to P. italosignus and N. campestris, whereas no trasmissions occurred with L. tunetana. The known vector Philaenus spumarius has been included in all the experiments for validation. The systematic surveys conducted in 2016 and 2017 provided further evidence on the population dynamics and seasonal abundance of the spittlebug populations in the olive groves.

scholarly journals Focal Accumulation of ROS Can Block Pyricularia oryzae Effector BAS4-Expression and Prevent Infection in Rice

2020 ◽  
Vol 21 (17) ◽  
pp. 6196
Author(s):  
Yafei Chen ◽  
Sarmina Dangol ◽  
Juan Wang ◽  
Nam-Soo Jwa
Keyword(s):  
Plant Immunity ◽  
Pathogenic Fungus ◽  
Hyphal Growth ◽  
Infection Process ◽  
Pyricularia Oryzae ◽  
High Concentrations ◽  
Ros Burst ◽  
Immunity Mechanism ◽  
Respiratory Burst Oxidase

The reactive oxygen species (ROS) burst is the most common plant immunity mechanism to prevent pathogen infection, although the exact role of ROS in plant immunity has not been fully elucidated. We investigated the expression and translocation of Oryza sativa respiratory burst oxidase homologue B (OsRBOHB) during compatible and incompatible interactions between rice epidermal cells and the pathogenic fungus Pyricularia oryzae (syn. Magnaporthe oryzae). We characterized the functional role of ROS focal accumulation around invading hyphae during P. oryzae infection process using the OsRBOHB inhibitor diphenyleneiodonium (DPI) and the actin filament polymerization inhibitor cytochalasin (Cyt) A. OsRBOHB was strongly induced during incompatible rice–P. oryzae interactions, and newly synthesized OsRBOHB was focally distributed at infection sites. High concentrations of ROS focally accumulated at the infection sites and suppressed effector biotrophy-associated secreted (BAS) proteins BAS4 expression and invasive hyphal growth. DPI and Cyt A abolished ROS focal accumulation and restored P. oryzae effector BAS4 expression. These results suggest that ROS focal accumulation is able to function as an effective immune mechanism that blocks some effectors including BAS4-expression during P. oryzae infection. Disruption of ROS focal accumulation around invading hyphae enables successful P. oryzae colonization of rice cells and disease development.

scholarly journals Role of plant cell in host-pathogen interactions: Lactuca spp.-Bremia lactucae

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 507-509
Author(s):  
M. Sedlářová ◽  
A. Lebeda ◽  
P. Binarová ◽  
L. Luhová
Keyword(s):  
Phenolic Compounds ◽  
Fungal Infection ◽  
Hypersensitive Reaction ◽  
Microscopical Study ◽  
Infection Process ◽  
The Other ◽  
Bremia Lactucae ◽  
Host Pathogen ◽  
Resistant Genotypes

Reactions of Lactuca spp. genotypes with different mechanisms of compatibility/incompatibility to B. lactucae race NL16 were examined. Microscopical study revealed significance of initial stages of infection for establishment of the host-pathogen relation. Incompatibility to the pathogen race is mostly expressed as hypersensitive reaction (HR). Rearrangement of cytoskeleton can participate in blocking of fungus penetration in resistant genotypes as well as support development of fungal infection structures in susceptible ones. During infection process peroxidase is activated, H<sub>2</sub>O<sub>2</sub> released and phenolic compounds deposited. These defence processes well correspond with the expression of resistance. On the other hand, formation of callose attending pathogenesis is not directly related to incompatibility.

scholarly journals HPLC-MS/MS method applied to an untargeted metabolomics approach for the diagnosis of “olive quick decline syndrome”

2021 ◽  
Author(s):  
Sabrina Di Masi ◽  
Giuseppe E. De Benedetto ◽  
Cosimino Malitesta ◽  
Maria Saponari ◽  
Cinzia Citti ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
High Performance ◽  
High Resolution Mass Spectrometry ◽  
Xylella Fastidiosa ◽  
Long Chain Fatty Acids ◽  
Powerful Approach ◽  
Diffusible Signal Factor ◽  
Profile Changes ◽  
Olive Quick Decline Syndrome ◽  
Olive Trees

AbstractOlive quick decline syndrome (OQDS) is a disorder associated with bacterial infections caused by Xylella fastidiosa subsp. pauca ST53 in olive trees. Metabolic profile changes occurring in infected olive trees are still poorly investigated, but have the potential to unravel reliable biomarkers to be exploited for early diagnosis of infections. In this study, an untargeted metabolomic method using high-performance liquid chromatography coupled to quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-ESI-Q-TOF-MS) was used to detect differences in samples (leaves) from healthy (Ctrl) and infected (Xf) olive trees. Both unsupervised and supervised data analysis clearly differentiated the groups. Different metabolites have been identified as potential specific biomarkers, and their characterization strongly suggests that metabolism of flavonoids and long-chain fatty acids is perturbed in Xf samples. In particular, a decrease in the defence capabilities of the host after Xf infection is proposed because of a significant dysregulation of some metabolites belonging to flavonoid family. Moreover, oleic acid is confirmed as a putative diffusible signal factor (DSF). This study provides new insights into the host-pathogen interactions and confirms LC-HRMS-based metabolomics as a powerful approach for disease-associated biomarkers discovery in plants. Graphical abstract

Etude ultrastructurale des relations hôte–parasite au cours de l'infection des pommes par le Phytophthora cactorum

1981 ◽  
Vol 59 (2) ◽  
pp. 251-263 ◽  
Author(s):  
X. Mourichon ◽  
G. Sallé
Keyword(s):  
Cell Walls ◽  
Susceptible Variety ◽  
Host Cells ◽  
Phytophthora Cactorum ◽  
Electron Microscopic ◽  
Susceptible Host ◽  
Golden Delicious ◽  
Extrahaustorial Matrix ◽  
Apple Fruits

An electron microscopic study was performed on haustoria of Phytophthora cactorum (L. et C.) Schroeter developed in tissues of two cultivars of apple fruits: a susceptible variety ('Golden delicious') and a resistant one ('Belle de Boskoop'). Ultrastructure of intercellular hyphae and some aspects of their penetration between contiguous host cells were described. A light dissolution of the host cell walls was observed. Ontogenic investigations indicated that in the susceptible host, the wall of the fungal haustoria was covered with a dense-stained extrahaustorial matrix. Its origin and its polysaccharide nature were demonstrated. On the other hand, the resistant host developed, immediately after the inoculation, a papilla which gave rise, later on, to a sheath enclosing adult haustoria. The role of these callosic structures in the phenomenon of resistance was discussed.

scholarly journals Adaptation of Newcastle Disease Virus (NDV) in Feral Birds and their Potential Role in Interspecies Transmission

2018 ◽  
Vol 12 (1) ◽  
pp. 52-68 ◽  
Author(s):  
Aziz-ul- Rahman ◽  
Momena Habib ◽  
Muhammad Zubair Shabbir
Keyword(s):  
Newcastle Disease ◽  
Potential Role ◽  
Vital Role ◽  
Wild Birds ◽  
Avian Species ◽  
Phylogenomic Analysis ◽  
Susceptible Host ◽  
Domestic Poultry ◽  
Wide Range

Introduction:Newcastle Disease (ND), caused by Avian avulavirus 1 (AAvV 1, avulaviruses), is a notifiable disease throughout the world due to the economic impact on trading restrictions and its embargoes placed in endemic regions. The feral birds including aquatic/migratory birds and other wild birds may act as natural reservoir hosts of ND Viruses (NDVs) and may play a remarkable role in the spread of the virus in environment. In addition, other 19 avulaviruses namely: AAvV 2 to 20, have been potentially recognized from feral avian species.Expalantion:Many previous studies have investigated the field prevailing NDVs to adapt a wide range of susceptible host. Still the available data is not enough to declare the potential role of feral birds in transmission of the virus to poultry and/or other avian birds. In view of the latest evidence related to incidences of AAvVs in susceptible avian species, it is increasingly important to understand the potential of viruses to transmit within the domestic poultry and other avian hosts. Genomic and phylogenomic analysis of several investigations has shown the same (RK/RQRR↓F) motif cleavage site among NDV isolates with same genotypes from domestic poultry and other wild hosts. So, the insight of this, various semi-captive/free-ranging wild avian species could play a vital role in the dissemination of the virus, which is an important consideration to control the disease outbreaks. Insufficient data on AAvV 1 transmission from wild birds to poultry and vice versa is the main constraint to understand about its molecular biology and genomic potential to cause infection in all susceptible hosts.Conclusion:The current review details the pertinent features of several historical and contemporary aspects of NDVs and the vital role of feral birds in its molecular epidemiology and ecology.

scholarly journals Cigarrinhas dos Citros, Vetoras da Bactéria Xylella fastidiosa Wells et al.: Pragas Potenciais para a Citricultura Sergipana

2015 ◽  
Vol 8 (1) ◽  
pp. 01-07
Author(s):  
Ruberval Leone Azevedo ◽  
Marcel Faria Lima
Keyword(s):  
Xylella Fastidiosa ◽  
Sao Paulo ◽  
The State ◽  
Northern Coast ◽  
São Paulo ◽  
Citrus Industry ◽  
National Production ◽  
Potential Pest ◽  
The Many

A citricultura no Brasil exerce um papel de grande importância econômica, social, gerando empregos, renda e desenvolvimento. O Brasil é o maior produtor mundial de citros, o Estado de Sergipe destaca-se em 5º lugar nacional em produção. Dentre os vários problemas fitossanitários enfrentados pela citricultura brasileira está a Clorose Variegada dos Citros (CVC), conhecida como amarelinho, causada pela bactéria Xylella fastidiosa Wells et al. A CVC foi identificada oficialmente no Brasil, em 1987, em pomares do Triângulo Mineiro e do Norte e Noroeste do Estado de São Paulo. No Nordeste, foi constatada em 1996 em Sergipe no município de Boquim, e em 1997 na Bahia, nos municípios de Rio Real e Itapicuru. O objetivo foi revisar a literatura sobre as espécies de cigarrinhas vetores da CVC, e verificar se ocorrem no estado de Sergipe. Os primeiros sintomas são vistos nas folhas, passam posteriormente para os frutos e acabam afetando toda a planta, e para serem percebidos pode levar entre 5 meses e 2 anos. Os principais vetores da X. fastidiosa em citros são as cigarrinhas da família Cicadellidae. No Brasil já foram confirmadas 12 espécies de cigarrinhas vetoras. Para o estado de Sergipe, são escassas a informações sobre Cicadellidae vetoras, os dados são limitados ao Litoral Norte da Bahia, com exceção de vaga citação sobre quatro gêneros (Oncometropia, Acrogonia, Dilobopterus e Homolodisca) e três espécies (Homolodisca ignorata Melichar, Acrogonia sp. e Homolodisca spottii Takiya, Cavichioli & McKamey). Citrus leafhoppers, Vectors of of Bacterium Xylella fastidiosa Wells et al.: Potential Pest of Citrus Crops in Sergipe State Abstract. The citrus industry in Brazil plays a role of great economic, social, generating jobs, income and development. Brazil is the largest producer of citrus, the State of Sergipe stands out in 5th place in national production. Among the many pest problems faced by Brazilian citrus is Citrus Variegated Chlorosis (CVC), known as the yellowing caused by the bacterium Xylella fastidiosa Wells et al. The CVC was officially identified in Brazil in 1987, in orchards of “Triângulo Mineiro” and North and northwest of the state of São Paulo. In the Northeast Region of Brazil, was found in 1996 in the municipality of Boquim Sergipe, and Bahia in 1997, the municipalities of Rio Real and Itapicuru. The aim was to review the literature on the species of leafhoppers vectors of CVC, and verify that occur in the state of Sergipe. The first symptoms are seen in the leaves, then go for the fruits and end up affecting the entire plant, and to be perceived can take between five months and two years. The main vectors of X. fastidiosa in citrus are the sharpshooters of the family Cicadellidae. In Brazil 12 sharpshooters species have already been confirmed. For the state of Sergipe, is scarce information about the Cicadellidae vectors, the data are limited to the northern coast of Bahia, except for vague quote about four genus (Oncometropia, Acrogonia, Dilobopterus and Homolodisca) and three species (Homolodisca ignorata Melichar, Acrogonia sp. and Homolodisca spottii Takiya, Cavichioli & McKamey).

scholarly journals A Phytophthora capsici RXLR effector manipulates plant immunity by targeting RAB proteins and disturbing vesicle-mediated protein trafficking pathway

2021 ◽  
Author(s):  
Tianli Li ◽  
Gan Ai ◽  
Xiaowei Fu ◽  
Jin Liu ◽  
Hai Zhu ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Plant Immunity ◽  
Phytophthora Capsici ◽  
Functional Characterization ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Infection Process ◽  
Small Gtpase ◽  
Rab Proteins ◽  
Rxlr Effector

The oomycete pathogen Phytophthora capsici encodes hundreds of RXLR effectors to enter plant cells and suppress host defense responses. Only few of them are conserved across different strains and species. Such ‘core effectors’ may target hub immunity pathways that are essential during Phytophthora pathogens interacting with their hosts. However, the underlying mechanisms of core RXLRs-mediated host immunity manipulation are largely unknown. Here, we report the functional characterization of a P. capsici RXLR effector, RXLR242. RXLR242 expression is highly induced during the infection process. Its ectopic expression in Nicotiana benthamiana promotes Phytophthora infection. RXLR242 physically interacts with a group of RAB proteins, which belong to the small GTPase family and function in specifying transport pathways in the intracellular membrane trafficking system. RXLR242 impedes the secretion of PATHOGENESIS-RELATED 1 (PR1) protein to the apoplast by interfering the formation of RABE1-7-labeled vesicles. Further analysis indicated that such phenomenon is resulted from competitive binding of RXLR242 to RABE1-7. RXLR242 also interferes trafficking of the membrane-located receptor FLAGELLIN-SENSING 2 (FLS2) through competitively interacting with RABA4-3. Taken together, our work demonstrates that RXLR242 manipulates plant immunity by targeting RAB proteins and disturbing vesicle-mediated protein transporting pathway in plant hosts.

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