Project description:Investigation of whole genome gene expression level changes in Xylella fastidiosa grown in minimal media XFM and XFM supplied with pectin or glucan (Host polysaccharides) , compared to cell grown in the complex media PWG. The cells grown in the minimal medium XFM supplied with host polysaccharides specially pectin are transmissible by the insect vector when delivered to the vector through artificial diet system. This does not happen with cells grown in the complex media. 4 (4 plex chips) study using total RNA recovered from 4 independents replicates for Xylella fastidiosa grown on PWG, XFM, XFM-glucan and XFM-pectin.
Project description:This is the study of the Heat Shock response of phytopathogenic bacteria Xylella fastidiosa. This series keeps the 25 minutes 40oC stimulus response (Aug 2005). Keywords: stress response; heat shock response
Project description:Investigation of whole genome gene expression level changes in Xylella fastidiosa grown in minimal media XFM and XFM supplied with pectin or glucan (Host polysaccharides) , compared to cell grown in the complex media PWG. The cells grown in the minimal medium XFM supplied with host polysaccharides specially pectin are transmissible by the insect vector when delivered to the vector through artificial diet system. This does not happen with cells grown in the complex media.
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:Pierce's disease, caused by the bacterium Xylella fastidiosa, is one of the most devastating diseases of cultivated grapes. To test the long-standing hypothesis that Pierce's disease results from pathogen-induced drought stress, we used the Affymetrix Vitis GeneChip to compare the transcriptional response of Vitis vinifera to Xylella infection, water deficit, or a combination of the two stresses. The results reveal a massive redirection of gene transcription involving 822 genes with a minimum 2-fold change (p<0.05), including the upregulation of transcripts for phenylpropanoid and flavonoid biosynthesis, pathogenesis related (PR) proteins, absisic acid (ABA)/jasmonic acid (JA)-responsive transcripts, and down-regulation of transcripts related to photosynthesis, growth and nutrition. Although the transcriptional response of plants to Xylella infection was largely distinct from the response of healthy plants to water stress, we find that 138 of the pathogen-induced genes exhibited a significantly stronger transcriptional response when plants were simultaneously exposed to infection and drought stress, suggesting a strong interaction between disease and water deficit. This interaction between drought stress and disease was mirrored in planta at the physiological level for aspects of water relations and photosynthesis, and in terms of the severity of disease symptoms and the extent of pathogen colonization, providing a molecular correlation of the classical concept of the disease triangle where environment impacts disease severity. Mature leaves were sampled from 2-year old V. vinifera cv. Cabernet sauvignon clone 8 vines 4 and 8 weeks post-mock or inoculation with Xylella fastidiosa (Pierce's disease). Vines were grown in growth chambers under non-water limiting and water limiting conditions (moderate and severe water stress)
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: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.