Project description:Bacteria use a variety of mechanisms, such as two‐component regulatory systems (TCSs), to rapidly sense and respond to distinct conditions and signals in their host organisms. For example, a type III secretion system (T3SS) is the key determinant of the virulence of the model plant pathogen Pseudomonas syringae and contains the TCS RhpRS as a key regulator. However, the signal sensed by RhpRS remains unknown. We found that RhpRS directly senses plant-generated polyphenols and responds by switching off P. syringae T3SS via crosstalk with alternative histidine kinases. Through a chemical screen, we identified three natural polyphenols (tannic acid, 1,2,3,4,6-pentagalloylglucose and epigallocatechin gallate) that induced the expression of the rhpRS operon in a RhpS-dependent manner.
Project description:Pseudomonas syringae, a Gram-negative plant pathogen, infects more than 50 crops with its type III secretion system (T3SS) and causes severe economic losses around the world. Although the mechanisms of virulence-associated regulators of P. syringae T3SS have been studied for decades, the crosstalk and network underlying these regulators are still elusive. Previously, we have individually studied a group of T3SS regulators, including AefR, HrpS, and RhpRS. In the present study, we found 4 new T3SS regulator genes (envZ, ompR, tsiS and phoQ) via transposon-mediated mutagenesis. Two-component systems EnvZ and TsiS natively regulate T3SS. In order to uncover the crosstalk between 16 virulence-associated regulators, (including AefR, AlgU, CvsR, GacA, HrpL, HrpR, HrpS, MgrA, OmpR, PhoP, PilR, PsrA, RhpR, RpoN, TsiR and Vfr) in P. syringae, we mapped an intricate network named PSVnet (Pseudomonas syringae Virulence Regulatory Network) by combining differentially expression genes in RNA-seq and binding loci in ChIP-seq of all regulators.
Project description:This study evaluates the transcriptome of transgenic Arabidopsis seedlings expressing the effector HopBB1 from the bacteria Pseudomonas syringae
Project description:We implemented transcriptional analysis methods using cDNA and high-throughput sequencing data to identify HrpL-regulated genes for six strains of Pseudomonas syringae
Project description:Bacteria relies on two-component systems (TCSs) to respond to a wide range of stimuli or environmental cues for their survival and virulence. However, the functions and synergistic actions of TCSs in genomic level remains unclear. Here, in model phytopathogen Pseudomonas syringae, by integrating multiomics data, we developed a network-based PSTCSome (Pseudomonas syringae two-component systems regulome) to identify functions and crosstalk among global TCSs under either virulence suppressing (King’s B medium, KB) or activating conditions (minimal medium, MM). Transcriptome profiling identifies 2,099 differentially expressed genes (DEGs) in KB and 1,250 DEGs in MM, while ChIP-seq identifies 1,628 target genes across the whole genome. The multiomics results are applied to perform not only gene ontology (GO) analysis to detect the biological processes that TCSs involved in, but also subnetworks and co-expression analysis of 8 virulence-related pathways to decipher the TCSs regulated pathogenic behaviors. The following phenotypic experiments newly confirmed 8 TCSs that regulates type III secretion system (T3SS) (PSPPH_0253, PSPPH_2606, PSPPH_4416, and PSPPH_4451) and surface attachment (PSPPH_0253, PSPPH_3041, PSPPH_3473, PSPPH_3736, PSPPH_4001). We then compute 259 functional genes in KB and 161 in MM for those cluster TCSs. Analysis of cluster TCSs regulons led to the identification of either novel functions or 2 master regulatory TCSs (RhpS/RhpR and PSPPH_4827/4828) toward virulence. Our results show that TCSs in P. syringae dynamically adjust their regulatory networks by sensing the external environment, and then switch bacteria between pathogenic and non-pathogenic states in a sophisticated way. Furthermore, we present an online platform of PSTCSome to facilitate updating, network visualization and user-customized analyses.
Project description:In order to better understand the transcriptional networks triggered by pathogen inoculation, we monitored gene expression in leaves of mutant Arabidopsis plants, inoculated with Pseudomonas syringae ES4326 and wild type Col-0 plants grown in parallel. Individual leaves were injected in the morning using a needle-less syringe with 10E5 cfu cm-2 PsmES4326 (suspended in 5 mM MgSO4). For the wild type, leaves were also mock treated with 5 mM MgSO4. Leaves were harvested 24 hours later. Plants were grown in pots with BM-2 soil (Berger Peat Moss Ltd, Quebec, Canada) at a density of 9 plants per pot and kept at 22 degrees Celsius with 75% humidity and a 12 hour day length. Keywords: Expression profilling by array
Project description:Many bacteria can transition from a planktonic lifestyle to life attached to a surface. Changes in gene expression have been documented in bacteria in mature biofilms, but few studies have looked at gene expression during the initial stages of surface attachment. To investigate this, we performed RNA-Seq using the model organism Pseudomonas syringae B728a which has been found in rivers and lakes but is known for living on the leaf surface. We compared gene expression of wild-type P. syringae B728a cells attached to a filter for 2 hours to the gene expression of wild-type P. syringae B728a cells in King's medium B broth. We found that certain gene catergories were quickly induced when cells were on a surface such as flagellar synthesis and motility while other gene categories were quickly repressed such as phytotoxin synthesis and transport. These fast changes in gene expression suggest that P. syringae B728a uses surface attachment as a potential cue to better adapt to life on a surface.
Project description:We implemented transcriptional analysis methods using cDNA and high-throughput sequencing data to identify HrpL-regulated genes for six strains of Pseudomonas syringae Each Pseudomonas syringae strains was transformed with either pBAD::EV or pBAD containing native hrpL sequence. Strains were grown in MM media supplemented with arabinose and collected 1, 3, and 5 hours post arabinose treatment. RNA was extracted for each time point and mixed at a 1/3 ratio. After removal of rRNA, double stranded cDNA was generated and library prepared accordeing to Illumina protocols.
Project description:Pseudomonas syringae pv. syringae 9644 (Pss9644) is a causal agent of bacterial cherry canker causing necrotic symptoms on leaves, fruits, gummosis and canker in woody tissues of sweet cherry (Prunus avium). To understand which virulent factor genes were expressed in vitro, Pss9644 was grown in rich media (King's B Broth) and minimum media (hrp-inducing minimum media). The latter mimics the in planta environment.