Project description:In the xylem vessels of susceptible hosts, such as citrus trees or grapevines, Xylella fastidiosa forms biofilm like-colonies that can block water transport, which appears to correlate to disease symptoms. Besides helping host colonization, bacterial biofilms play an important role in resistance against antimicrobial agents, for instance antimicrobial peptides (AMP). Here we show that gomesin, a potent AMP from a Brazilian tarantula spider, modulates X. fastidiosa gene expression profile upon 60 min treatment with a sublethal concentration. Data from DNA microarray hybridizations revealed that among the up-regulated coding sequences (CDS), some are related to biofilm production. In addition, we show that the biofilm formed by gomesin-treated bacteria is thicker than that formed by non-treated cells or cells exposed to streptomycin. We have also observed that treatment of X. fastidiosa with sublethal concentration of gomesin before inoculation in tobacco plants correlates with reduction in CVC symptoms, an effect possibly due to trapping of bacterial cells to fewer xylem vessels given the enhancement in biofilm production. Together, our results suggest that X. fastidiosa can selectively sense a sublethal concentration of gomesin modulating its gene expression to produce a stronger biofilm that may protect itself against the toxic effects of this AMP.
Project description:In the xylem vessels of susceptible hosts, such as citrus trees or grapevines, Xylella fastidiosa forms biofilm like-colonies that can block water transport, which appears to correlate to disease symptoms. Besides helping host colonization, bacterial biofilms play an important role in resistance against antimicrobial agents, for instance antimicrobial peptides (AMP). Here we show that gomesin, a potent AMP from a Brazilian tarantula spider, modulates X. fastidiosa gene expression profile upon 60 min treatment with a sublethal concentration. Data from DNA microarray hybridizations revealed that among the up-regulated coding sequences (CDS), some are related to biofilm production. In addition, we show that the biofilm formed by gomesin-treated bacteria is thicker than that formed by non-treated cells or cells exposed to streptomycin. We have also observed that treatment of X. fastidiosa with sublethal concentration of gomesin before inoculation in tobacco plants correlates with reduction in CVC symptoms, an effect possibly due to trapping of bacterial cells to fewer xylem vessels given the enhancement in biofilm production. Together, our results suggest that X. fastidiosa can selectively sense a sublethal concentration of gomesin modulating its gene expression to produce a stronger biofilm that may protect itself against the toxic effects of this AMP. Two-condition experiment, control (PW media) vs. gomesin-treated cells. Biological replicates: 5 control, 5 gomesin-treated, independently grown and harvested. Two replicates (left and right side of slide) per array. Total of 10 slides were hibridized, including dye-swap of and two self-self experiments.
Project description:Xylella fastidiosa regulates traits important to both virulence of grape as well as colonization of sharpshooter vectors via its production of a fatty acid signal molecule known as DSF whose production is dependent on rpfF. While X. fastidiosa rpfF mutants exhibit increased virulence to plants they are unable to be spread from plant to plant by insect vectors. To gain more insight into the traits that contribute to these processes, a DNA microarray for this species was designed and utilized to determine the RpfF-dependent regulon by transcriptional profiling. A total of 447 genes whose expression was significantly different between the wild type and an rpfF mutant (FDR<0.05) were identified when cells were grown in PW liquid medium. Among them, 165 genes were down-regulated in the rpfF mutant compared to the wild type strain whereas 282 genes were over-expressed. RpfF function was required for regulation of eleven regulatory and sigma factors including rpfE, yybA, PD1177, glnB, rpfG, PD0954, PD0199, PD2050, colR, rpoH, and rpoD. In general, RpfF is required for regulation of genes involved in attachment and biofilm formation, enhancing expression of hemagglutinin genes hxfA and hxfB and suppressing most type IV pili and gum genes. A large number of other RpfF-dependent genes that might contribute to virulence or insect colonization were also identified such as those encoding hemolysin, colicin V, as well as genes with unknown functions.
Project description:Xylella fastidiosa regulates traits important to both virulence of grape as well as colonization of sharpshooter vectors via its production of a fatty acid signal molecule known as DSF whose production is dependent on rpfF. While X. fastidiosa rpfF mutants exhibit increased virulence to plants they are unable to be spread from plant to plant by insect vectors. To gain more insight into the traits that contribute to these processes, a DNA microarray for this species was designed and utilized to determine the RpfF-dependent regulon by transcriptional profiling. A total of 447 genes whose expression was significantly different between the wild type and an rpfF mutant (FDR<0.05) were identified when cells were grown in PW liquid medium. Among them, 165 genes were down-regulated in the rpfF mutant compared to the wild type strain whereas 282 genes were over-expressed. RpfF function was required for regulation of eleven regulatory and sigma factors including rpfE, yybA, PD1177, glnB, rpfG, PD0954, PD0199, PD2050, colR, rpoH, and rpoD. In general, RpfF is required for regulation of genes involved in attachment and biofilm formation, enhancing expression of hemagglutinin genes hxfA and hxfB and suppressing most type IV pili and gum genes. A large number of other RpfF-dependent genes that might contribute to virulence or insect colonization were also identified such as those encoding hemolysin, colicin V, as well as genes with unknown functions. Two samples and one time-points experiment. Two biological and dye-swap replicates of each strain were used.
Project description:Xylella fastidiosa is a plant pathogenic bacterium that has been introduced in the European Union (EU), threatening the agricultural economy of relevant Mediterranean crops such as almond (Prunus dulcis). Plant defense elicitor peptides would be promising to manage diseases such as almond leaf scorch but their effect on the host has not been fully studied. In this work, the response of almond plants to the defense elicitor peptide flg22-NH2 was studied in-depth using RNA-seq, confirming the activation of the salicylic acid and abscisic acid pathways. Marker genes related to the response triggered by flg22-NH2 were used to study the effect of the application strategy of the peptide on almond plants and to depict its time course. The application of flg22-NH2 by endotherapy triggered the highest number of upregulated genes, especially at 6 hours after the treatment. A library of peptides that include BP100-flg15, HpaG23, FV7, RIJK2, PIP-1, Pep13, BP16-Pep13, flg15-BP100 and BP16 triggered a stronger defense response in almond plants than flg22-NH2. The best candidate, FV7, when applied by endotherapy on almond plants inoculated with X. fastidiosa, significantly reduced levels of the pathogen and decreased disease symptoms. Therefore, these novel plant defense elicitors are suitable candidates to manage diseases caused by X. fastidiosa, in particular almond leaf scorch.
Project description:Antimicrobial resistance (AMR) has become a serious public and economic threat. The rate of bacteria acquiring AMR surpasses the rate of new antibiotics discovery, projecting more deadly AMR infections in the future. The Pathogen Box is an open-source library of drug-like compounds that can be screened for antibiotic activity. We have screened molecules of the Pathogen Box against Vibrio cholerae, the cholera-causing pathogen, and successfully identified two compounds, MMV687807 and MMV675968, that inhibit growth. RNA-seq analyses of V. cholerae after incubation with each compound revealed that both compounds affect cellular functions on multiple levels including carbon metabolism, iron homeostasis, and biofilm formation. In addition, whole-genome sequencing analysis of spontaneous resistance mutants identified an efflux system that confers resistance to MMV687807. We also identified that the dihydrofolate reductase is the likely target of MMV675968 suggesting it acts as an analog of trimethoprim but with a minimum inhibitory concentration (MIC) 14-fold lower than trimethoprim in molar concentration. In summary, these two compounds that effectively inhibit V. cholerae and other bacteria may lead to the development of new antibiotics for better treatment of the cholera disease.
Project description:Xylella fastidiosa (Xf) is a Gram-negative bacterial plant pathogen responsible for severe diseases in a variety of economically important crops. A critical aspect of its virulence is the production of extracellular vesicles (EVs). In this study, we discovered that DNA-binding proteins and non-ribosomal RNA-binding proteins are abundant in the corona of Xf-EVs. DNA-seq revealed enrichment of three genomic islands (GIS) in EVs, which carry molecular signatures indicative of horizontal gene transfer (HGT). The most abundant GI encodes five homologous small RNAs designated sXFs. RNA sequencing revealed a distinct pattern of non-coding RNAs enriched in EVs, including four island-encoded sXFs. One of the sXF’s stem-loops contains motifs for binding the RNA chaperone Hfq, which is also abundant in EVs. Predicted target analysis suggests that sXFs play a role in regulation of natural competence in bacteria. Additionally, sXF plant target prediction identifies a coiled-coil nucleotide-binding domain leucine-rich repeat receptor (CNL) immune gene that is downregulated following Xf infection and Xf-EV treatment. We propose a model where Xf releases nucleic acid carrying EVs with two functions: one to deliver RNA-related cargo that regulates gene expression in both bacterial and plant cells, and another to deliver DNA-related cargo for the genetic transfer of genomic islands. We highlight island-encoded sXFs as potential virulence factors and vesiduction as a mechanism of horizontal gene transfer of sXFs in Xf. Taken together, our data on Xf-EV cargoes provide a molecular framework for understanding the virulence of Xf.