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:We used three different strains of Pseudomonas syringae pv tomato DC3000 to investigate systemic responses to infection in Arabidopsis and the development of SAR. Wildtype DC3000, the hrpA mutant and DC3000 carrying the avirulence gene avrRpm1 were syringe infiltrated into 4-week-old plants at a concentration of 10e8 cfu/ml. At least 5 leaves per plant were infiltrated and at least 10 plants were pooled for each sample. Systemic, uninfected tissue was then harvested at 8, 12 and 21h after inoculation. Three independent experiments were carried out to give three biological replicates for each timepoint.
Project description:This study evaluates the transcriptome of Arabidopsis thaliana infected with the Pseudomonas syringae strain DC3000 cor- carrying the type three secretion system effector HopBB1
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 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: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:We used three different strains of Pseudomonas syringae pv tomato DC3000 to investigate systemic responses to infection in Arabidopsis and the development of SAR. Wildtype DC3000, the hrpA mutant and DC3000 carrying the avirulence gene avrRpm1 were syringe infiltrated into 4-week-old plants at a concentration of 10e8 cfu/ml. At least 5 leaves per plant were infiltrated and at least 10 plants were pooled for each sample. Systemic, uninfected tissue was then harvested at 8, 12 and 21h after inoculation. Three independent experiments were carried out to give three biological replicates for each timepoint. 27 samples were used in this experiment.
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.
