scholarly journals Expression of Xylella fastidiosa RpfF in Citrus Disrupts Signaling in Xanthomonas citri subsp. citri and Thereby Its Virulence

2014 ◽  
Vol 27 (11) ◽  
pp. 1241-1252 ◽  
Author(s):  
R. Caserta ◽  
S. C. Picchi ◽  
M. A. Takita ◽  
J. P. Tomaz ◽  
W. E. L. Pereira ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Citrus Sinensis ◽  
Virulence Genes ◽  
Xylella Fastidiosa ◽  
Xylem Sap ◽  
Citrus Canker ◽  
Symptom Development ◽  
Xanthomonas Citri ◽  
Diffusible Signal Factor ◽  
Transgenic Citrus

Xylella fastidiosa and Xanthomonas citri subsp. citri, that cause citrus variegated chlorosis (CVC) and citrus canker diseases, respectively, utilize diffusible signal factor (DSF) for quorum sensing. DSF, produced by RpfF, are similar fatty acids in both organisms, although a different set of genes is regulated by DSF in each species. Because of this similarity, Xylella fastidiosa DSF might be recognized and affect the biology of Xanthomonas citri. Therefore, transgenic Citrus sinensis and Carrizo citrange plants overexpressing the Xylella fastidiosa rpfF were inoculated with Xanthomonas citri and changes in symptoms of citrus canker were observed. X. citri biofilms formed only at wound sites on transgenic leaves and were thicker; however, bacteria were unable to break through the tissue and form pustules elsewhere. Although abundant growth of X. citri occurred at wound sites on inoculated transgenic leaves, little growth was observed on unwounded tissue. Genes in the DFS-responsive core in X. citri were downregulated in bacteria isolated from transgenic leaves. DSF-dependent expression of engA was suppressed in cells exposed to xylem sap from transgenic plants. Thus, altered symptom development appears to be due to reduced expression of virulence genes because of the presence of antagonists of DSF signaling in X. citri in rpfF-expressing plants.

scholarly journals Promiscuous Diffusible Signal Factor Production and Responsiveness of the Xylella fastidiosa Rpf System

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Michael Ionescu ◽  
Kenji Yokota ◽  
Elena Antonova ◽  
Angelica Garcia ◽  
Ellen Beaulieu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fatty Acids ◽  
Quorum Sensing ◽  
Xanthomonas Campestris ◽  
Unsaturated Fatty Acids ◽  
Xylella Fastidiosa ◽  
Biologically Active ◽  
Dependent Manner ◽  
Growth Environment ◽  
Diffusible Signal Factor

ABSTRACT Cell density-dependent regulation of gene expression in Xylella fastidiosa that is crucial to its switching between plant hosts and insect vectors is dependent on RpfF and its production of 2-enoic acids known as diffusible signal factor (DSF). We show that X. fastidiosa produces a particularly large variety of similar, relatively long-chain-length 2-enoic acids that are active in modulating gene expression. Both X. fastidiosa itself and a Pantoea agglomerans surrogate host harboring X. fastidiosa RpfF ( Xf RpfF) is capable of producing a variety of both saturated and unsaturated free fatty acids. However, only 2- cis unsaturated acids were found to be biologically active in X. fastidiosa . X. fastidiosa produces, and is particularly responsive to, a novel DSF species, 2- cis -hexadecanoic acid that we term Xf DSF2. It is also responsive to other, even longer 2-enoic acids to which other taxa such as Xanthomonas campestris are unresponsive. The 2-enoic acids that are produced by X. fastidiosa are strongly affected by the cellular growth environment, with Xf DSF2 not detected in culture media in which 2-tetradecenoic acid ( Xf DSF1) had previously been found. X. fastidiosa is responsive to much lower concentrations of Xf DSF2 than Xf DSF1. Apparently competitive interactions can occur between various saturated and unsaturated fatty acids that block the function of those agonistic 2-enoic fatty acids. By altering the particular 2-enoic acids produced and the relative balance of free enoic and saturated fatty acids, X. fastidiosa might modulate the extent of DSF-mediated quorum sensing. IMPORTANCE X. fastidiosa , having a complicated lifestyle in which it moves and multiplies within plants but also must be vectored by insects, utilizes DSF-based quorum sensing to partition the expression of traits needed for these two processes within different cells in this population based on local cellular density. The finding that it can produce a variety of DSF species in a strongly environmentally context-dependent manner provides insight into how it coordinates the many genes under the control of DSF signaling to successfully associate with its two hosts. Since the new DSF variant Xf DSF2 described here is much more active than the previously recognized DSF species, it should contribute to plant disease control, given that the susceptibility of plants can be greatly reduced by artificially elevating the levels of DSF in plants, creating “pathogen confusion,” resulting in lower virulence.

scholarly journals Production of Xylella fastidiosa Diffusible Signal Factor in Transgenic Grape Causes Pathogen Confusion and Reduction in Severity of Pierce's Disease

2014 ◽  
Vol 27 (3) ◽  
pp. 244-254 ◽  
Author(s):  
Steven Lindow ◽  
Karyn Newman ◽  
Subhadeep Chatterjee ◽  
Clelia Baccari ◽  
Anthony T. Iavarone ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Xylella Fastidiosa ◽  
Disease Incidence ◽  
Xylem Sap ◽  
Field Trials ◽  
Parental Line ◽  
Ionization Mass ◽  
Lateral Movement ◽  
Diffusible Signal Factor

The rpfF gene from Xylella fastidiosa, encoding the synthase for diffusible signal factor (DSF), was expressed in ‘Freedom’ grape to reduce the pathogen's growth and mobility within the plant. Symptoms in such plants were restricted to near the point of inoculation and incidence of disease was two- to fivefold lower than in the parental line. Both the longitudinal and lateral movement of X. fastidiosa in the xylem was also much lower. DSF was detected in both leaves and xylem sap of RpfF-expressing plants using biological sensors, and both 2-Z-tetradecenoic acid, previously identified as a component of X. fastidiosa DSF, and cis-11-methyl-2-dodecenoic acid were detected in xylem sap using electrospray ionization mass spectrometry. A higher proportion of X. fastidiosa cells adhered to xylem vessels of the RpfF-expressing line than parental ‘Freedom’ plants, reflecting a higher adhesiveness of the pathogen in the presence of DSF. Disease incidence in RpfF-expressing plants in field trials in which plants were either mechanically inoculated with X. fastidiosa or subjected to natural inoculation by sharpshooter vectors was two- to fourfold lower in than that of the parental line. The number of symptomatic leaves on infected shoots was reduced proportionally more than the incidence of infection, reflecting a decreased ability of X. fastidiosa to move within DSF-producing plants.

scholarly journals Diffusible Signal Factor–Repressed Extracellular Traits Enable Attachment of Xylella fastidiosa to Insect Vectors and Transmission

2014 ◽  
Vol 104 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Clelia Baccari ◽  
Nabil Killiny ◽  
Michael Ionescu ◽  
Rodrigo P. P. Almeida ◽  
Steven E. Lindow
Keyword(s):  
Type Strain ◽  
Host Plants ◽  
Wild Type Strain ◽  
Culture Supernatant ◽  
Culture Media ◽  
Xylella Fastidiosa ◽  
Xylem Sap ◽  
Wild Type ◽  
Diffusible Signal Factor ◽  
Type Strains

The hypothesis that a wild-type strain of Xylella fastidiosa would restore the ability of rpfF mutants blocked in diffusible signal factor production to be transmitted to new grape plants by the sharpshooter vector Graphocephala atropunctata was tested. While the rpfF mutant was very poorly transmitted by vectors irrespective of whether they had also fed on plants infected with the wild-type strain, wild-type strains were not efficiently transmitted if vectors had fed on plants infected with the rpfF mutant. About 100-fewer cells of a wild-type strain attached to wings of a vector when suspended in xylem sap from plants infected with an rpfF mutant than in sap from uninfected grapes. The frequency of transmission of cells suspended in sap from plants that were infected by the rpfF mutant was also reduced over threefold. Wild-type cells suspended in a culture supernatant of an rpfF mutant also exhibited 10-fold less adherence to wings than when suspended in uninoculated culture media. A factor released into the xylem by rpfF mutants, and to a lesser extent by the wild-type strain, thus inhibits their attachment to, and thus transmission by, sharpshooter vectors and may also enable them to move more readily through host plants.

scholarly journals High-Throughput Screening and Analysis of Genes of Xanthomonas citri subsp. citri Involved in Citrus Canker Symptom Development

2012 ◽  
Vol 25 (1) ◽  
pp. 69-84 ◽  
Author(s):  
Qing Yan ◽  
Nian Wang
Keyword(s):  
High Throughput Screening ◽  
Extracellular Polysaccharide ◽  
Citrus Canker ◽  
Symptom Development ◽  
Genetic Determinants ◽  
Xanthomonas Citri ◽  
Novel Genes ◽  
Sensing System ◽  
Severe Reduction ◽  
Quorum Sensing System

Citrus canker is caused by Xanthomonas citri subsp. citri and is one of the most devastating diseases on citrus plants. To investigate the virulence mechanism of this pathogen, a mutant library of strain 306 containing approximately 22,000 mutants was screened for virulence-deficient mutants in grapefruit (Citrus paradise). Eighty-two genes were identified that contribute to citrus canker symptom development caused by X. citri subsp. citri. Among the 82 identified genes, 23 genes were classified as essential genes, as mutation of these genes caused severe reduction of bacterial growth in M9 medium. The remaining 59 genes were classified as putative virulence-related genes that include 32 previously reported virulence-related genes and 27 novel genes. The 32 known virulence-related genes include genes that are involved in the type III secretion system (T3SS) and T3SS effectors, the quorum-sensing system, extracellular polysaccharide and lipopolysaccharide synthesis, and general metabolic pathways. The contribution to pathogenesis by nine genes (pthA4, trpG, trpC, purD, hrpM, peh-1, XAC1230, XAC1548, and XAC3049) was confirmed by complementation assays. We further validated the mutated genes and their phenotypes by analyzing the EZ-Tn5 insertion copy number using Southern blot analysis. In conclusion, we have significantly advanced our understanding of the putative genetic determinants of the virulence mechanism of X. citri subsp. citri by identifying 59 putative virulence-related genes, including 27 novel genes.

scholarly journals First report of Xanthomonas citri Subsp. Citri causing citrus canker on grape fruit (Citrus paradisi), washington naval (Citrus sinensis), kaghzi limon (Citrus aurantifolia Swingle), lemon (Citrus lim

2021 ◽  
Vol 58 (04) ◽  
pp. 1373-1377
Author(s):  
Muhammad Shah Nawaz ul Rehman
Keyword(s):  
Citrus Sinensis ◽  
Sequence Similarity ◽  
Citrus Canker ◽  
Citrus Limon ◽  
Evolutionary Analysis ◽  
Citrus Paradisi ◽  
Xanthomonas Citri ◽  
Citrus Aurantifolia ◽  
Grape Fruit ◽  
Citrus Maxima

Citrus fruit production is largely affected by different bacterial and fungal pathogens. In Pakistan bacterial diseases like citrus bacterial canker (CBC) pose severe risk to citrus economy. Diagnoses of such diseases could be helpful to avoid the epidemics in nurseries or orchids. In 2011-12, citrus canker symptoms i.e., callus-like outgrowths on leaves and fruits of grape fruit (Citrus paradisi), Washington naval (Citrus sinensis), Kaghzi Limon (Citrus aurantifolia swingle), lemon (Citrus Limon) and pomelo (Citrus maxima) were noticed in Sargodha district of Punjab, Pakistan. Bacteria i.e., yellow mucoid, Xanthomonas- like isolates, were isolated from these lesions. Bacteria isolated from these lesions were cultured and total DNA was isolated. A diagnostic fragment of 581 bp based on rpf genes of Xanthomonas citri pv. citri was amplified, cloned and completely sequenced. BLAST and evolutionary analysis revealed that these isolates show 100% sequence similarity and group with Xanthomonas citri subsp. citri from Argentina (CP023285) and Reunion (CP018858), (CP018854). To our knowledge, this is the first formal report of X. campestris pv. citri pathotypes A on Citrus paradise, Citrus sinensis, Citrus maxima, Citrus Limon and Citrus aurantifolia swingle in Pakistan

scholarly journals A Genomic and Transcriptomic Overview of MATE, ABC, and MFS Transporters in Citrus sinensis Interaction with Xanthomonas citri subsp. citri

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 794 ◽  
Author(s):  
Maria H. M. Julião ◽  
Saura R. Silva ◽  
Jesus A. Ferro ◽  
Alessandro M. Varani
Keyword(s):  
Plant Defense ◽  
Membrane Trafficking ◽  
Citrus Sinensis ◽  
Defense Mechanism ◽  
In Silico Analysis ◽  
Citrus Canker ◽  
Membrane Transporters ◽  
Major Facilitator Superfamily ◽  
Xanthomonas Citri ◽  
Mfs Transporters

The multi-antimicrobial extrusion (MATE), ATP-binding cassette (ABC), and major facilitator superfamily (MFS) are the main plant transporters families, playing an essential role in the membrane-trafficking network and plant-defense mechanism. The citrus canker type A (CC), is a devastating disease caused by Xanthomonas citri subsp. citri (Xac), affecting all citrus species. In this work, we performed an in silico analysis of genes and transcripts from MATE, ABC, and MFS families to infer the role of membrane transporters in Citrus-Xac interaction. Using as reference, the available Citrus sinensis genome and the citrus reference transcriptome from CitrusKB database, 67 MATE, 91 MFS, and 143 ABC genes and 82 MATE, 139 MFS, and 226 ABC transcripts were identified and classified into subfamilies. Duplications, alternative-splicing, and potentially non-transcribed transporters’ genes were revealed. Interestingly, MATE I and ABC G subfamilies appear differently regulated during Xac infection. Furthermore, Citrus spp. showing distinct levels of CC susceptibility exhibited different sets of transporters transcripts, supporting dissimilar molecular patterns of membrane transporters in Citrus-Xac interaction. According to our findings, 4 MATE, 10 ABC, and 3 MFS are potentially related to plant-defense mechanisms. Overall, this work provides an extensive analysis of MATE, ABC, and MFS transporters’ in Citrus-Xac interaction, bringing new insights on membrane transporters in plant-pathogen interactions.

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

Chlorine dioxide, peroxyacetic acid, and calcium oxychloride for post-harvest decontamination of citrus fruit against Xanthomonas citri subsp. citri, causal agent of citrus canker

2021 ◽  
Vol 146 ◽  
pp. 105679
Author(s):  
Franklin Behlau ◽  
Alexandre Paloschi ◽  
Tamiris G.S. Marin ◽  
Talita A. Santos ◽  
Henrique Ferreira ◽  
...  
Keyword(s):  
Chlorine Dioxide ◽  
Citrus Fruit ◽  
Citrus Canker ◽  
Causal Agent ◽  
Peroxyacetic Acid ◽  
Xanthomonas Citri ◽  
Post Harvest

scholarly journals Modified Monosaccharides Content of Xanthan Gum Impairs Citrus Canker Disease by Affecting the Epiphytic Lifestyle of Xanthomonas citri subsp. citri

2021 ◽  
Vol 9 (6) ◽  
pp. 1176
Author(s):  
Simone Cristina Picchi ◽  
Laís Moreira Granato ◽  
Maria Júlia Festa Franzini ◽  
Maxuel Oliveira Andrade ◽  
Marco Aurélio Takita ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Xanthan Gum ◽  
Wild Type Strain ◽  
Natural Infection ◽  
Citrus Canker ◽  
Wild Type ◽  
Xanthomonas Citri ◽  
Canker Disease ◽  
Key Enzyme ◽  
Citrus Canker Disease

Xanthomonas citri subsp. citri (X. citri) is a plant pathogenic bacterium causing citrus canker disease. The xanA gene encodes a phosphoglucomutase/phosphomannomutase protein that is a key enzyme required for the synthesis of lipopolysaccharides and exopolysaccharides in Xanthomonads. In this work, firstly we isolated a xanA transposon mutant (xanA::Tn5) and analyzed its phenotypes as biofilm formation, xanthan gum production, and pathogenesis on the sweet orange host. Moreover, to confirm the xanA role in the impaired phenotypes we further produced a non-polar deletion mutant (ΔxanA) and performed the complementation of both xanA mutants. In addition, we analyzed the percentages of the xanthan gum monosaccharides produced by X. citri wild-type and xanA mutant. The mutant strain had higher ratios of mannose, galactose, and xylose and lower ratios of rhamnose, glucuronic acid, and glucose than the wild-type strain. Such changes in the saccharide composition led to the reduction of xanthan yield in the xanA deficient strain, affecting also other important features in X. citri, such as biofilm formation and sliding motility. Moreover, we showed that xanA::Tn5 caused no symptoms on host leaves after spraying, a method that mimetics the natural infection condition. These results suggest that xanA plays an important role in the epiphytical stage on the leaves that is essential for the successful interaction with the host, including adaptive advantage for bacterial X. citri survival and host invasion, which culminates in pathogenicity.

scholarly journals Transmission of the Citrus Variegated Chlorosis Bacterium Xylella fastidiosa with the Sharpshooter Oncometopia nigricans

Plant Disease ◽  
2002 ◽  
Vol 86 (11) ◽  
pp. 1237-1239 ◽  
Author(s):  
R. H. Brlansky ◽  
V. D. Damsteegt ◽  
J. S. Hartung
Keyword(s):  
United States ◽  
Polymerase Chain Reaction ◽  
Xylella Fastidiosa ◽  
The United States ◽  
Reliable Indicator ◽  
Symptom Development ◽  
Chain Reaction ◽  
Citrus Variegated Chlorosis ◽  
Specific Polymerase Chain Reaction ◽  
Polymerase Chain

Citrus variegated chlorosis (CVC) is an economically important, destructive disease in Brazil and is caused by the bacterium Xylella fastidiosa Wells. The bacterium has been found to be transmitted in Brazil by sharpshooter leafhoppers (Cicadellidae). Sharpshooters are present in most citrus growing areas of the United States. The sharpshooter leafhopper, Oncometopia nigricans Walker, frequently is found feeding on citrus in Florida. This sharpshooter transmits the X. fastidiosa strains that cause Pierce's disease of grape and ragweed stunt. Research was initiated to determine if O. nigricans was capable of vectoring the X. fastidiosa that causes CVC. In 59 different transmission tests, using 1 to 57 insects per test, transmission of the bacterium was observed 12 times (20.3%). Symptom development in the greenhouse was not a reliable indicator of transmission. Transmission was verified by specific polymerase chain reaction-based assays. Individual insects were able to transmit the bacterium. This information on sharpshooter transmission of CVC is needed to assess the threat posed by the CVC disease to the citrus industries in the United States.

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