Project description:Pseudomonas syringae pv. actinidiae biovar 6 (Psa6) is a causal agent of kiwifruit bacterial canker and is a unique plant pathogenic bacterium, producing two types of phytotoxins, coronatine and phaseolotoxin. We investigated the expression behavior of virulent genes of Psa6 under various culture conditions.
Project description:Purpose: The outcome of host–pathogen interactions is thought to reflect the offensive and defensive capabilities of both players. When plants interact with Pseudomonas syringae, several well-characterized virulence factors contribute to early bacterial pathogenicity, including the type III secretion system (T3SS), which must be activated by signals from the plant and environment to allow the secretion of virulence effectors. The manner in which these signals regulate T3SS activity is still unclear. Conlusion: the analysis revealed that the perception of plant signals from kiwifruit or tomato extracts anticipates T3SS expression in P. syringae pv. actinidiae compared to apoplast-like conditions
Project description:To study the responses of kiwifruit to Pseudomonas syringae pv. actinidiae, one-year-old potted seeding A. c. var. deliciosa cultivar ‘Jinkui’ and the pandemic Pseudomonas syringae pv. actinidiae bacterial strain JF8 (CCTCC AB2018305) were used for this study. This bacterial strain was originally isolated from A. c. var. chinensis cultivar ‘Jinfeng’ and further characterized . Plants were maintained in an aseptic room, with 95% of relative humidity, have natural light and no further fertilization after their receiving from the nursery. For inoculation, the P. s.pv. actinidiae strain was streaked on nutrient-sucrose agar (NSA) and incubated at 25 °C for 48-h. Ten microliters of a bacterial suspension (1-2×107cfu/mL) prepared in sterile 0.85 % w NaCl were inoculated in the plants chosen for investigation. The bacterial suspension was sprayed to entirety tree. In parallel, control plants were treated in the same way with sterile 0.85 % w NaCl solution. The inoculated and control plants were randomly distributed in the room at 15 ± 3 °C. 24-h after inoculation, ‘Jinkui’ leaves were sampled from the infected and control plants for further analyses. Each sample consisted of the leaves of one tree. Three biological replicates were used for each line.
Project description:Purpose: Pseudomonas syringae pv. actinidiae (Psa) is a phytopathogen that causes devastating bacterial canker in kiwifruit. Among five biovars defined by genetic, biochemical and virulence traits, Psa3 is the most aggressive and is responsible for the most recent reported outbreaks, but the molecular basis of its heightened virulence is unclear. A custom P. syringae multi-strain whole-genome microarray platform, encompassing biovars Psa1, Psa2 and Psa3 and the well-established model P. syringae pv. tomato, was used to analyse early bacterial responses to an apoplast-like minimal medium. Conlusion: this work highlighted that diverse early responses to the host apoplast, even among bacteria belonging to the same pathovar, can lead to different virulence strategies and may explain the differing outcomes of infections.
Project description:A ChIP-seq assay was performed to identify the regulons of an ompR-like transcription factor (gene name: 13375, GenBank: AYL80818.1) in Pseudomonas syringae pv. actinidiae. An 13375-overexpressing mutant G1-OE13375, which constitutively express C-terminally Myc-tagged ompR-like gene in the 13375-deletion mutant G1Δ13375, was used in this study. The bacterial cells were cultured either in nutrition-rich KB medium or hrp-derepressing medium (HDM) at 25 C for 24 hours. A PierceTM Magnetic ChIP Kit (Cat. #: 26157, Thermo Fisher Scientific) and a ChIP-grade Myc-Tag Monoclonal Antibody (Myc.A7, Cat. #: MA121316, Thermo Fisher Scientific) were used for sample pretreatment and immunoprecipitation.
Project description:Purpose: Microarray technologies provide a unique opportunity to deeply investigate bacterial molecular responses to treatments. Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of the bacterial canker of kiwifruit causing severe economic losses worldwide. At present, integrated control strategies include chemical treatments with copper-based products and preventive measures but the high virulence and fast spreading of the bacterium are hardly controlled by such measures, and especially copper use is questioned because of the possible appearance of copper resistant bacterial strains. The present project aims at the identification of Psa responses to green tea treatment (Gunpowder variety) at sub-lethal concentration (0.4 mg/ml). Methods: Psa cells were cultured in liquid KB (controls) or in KB supplemented with Gunpowder tea (Gunpowder-trateted) at 0.4 mg/ml EGCG for 24 h at 28°C. The microarray experiments on Gunpowder treated or untreated samples in biological triplicate resulted in 6 samples to be analyzed. Conclusions: This work identified important molecular mechanisms involved in Psa responses upon Gunpowder green tea treatment.
Project description:Disease resistance in plants depends on a molecular dialogue with microbes that involves many known chemical effectors, but the time course of the interaction and the influence of the environment are largely unknown. The outcome of host–pathogen interactions is thought to reflect the offensive and defensive capabilities of both players. When plants interact with Pseudomonas syringae, several well-characterized virulence factors contribute to early bacterial pathogenicity, including the type III secretion system (T3SS), which must be activated by signals from the plant and environment to allow the secretion of virulence effectors. The manner in which these signals regulate T3SS activity is still unclear. Here, we strengthen the paradigm of the plant–pathogen molecular dialogue by addressing overlooked details concerning the timing of interactions, specifically the role of plant signals and temperature on the regulation of bacterial virulence during the first few hours of the interaction. Whole-genome expression profiling after 1 h revealed that the perception of plant signals from kiwifruit or tomato extracts anticipates T3SS expression in P. syringae pv. actinidiae compared to apoplast-like conditions, facilitating more efficient effector transport in planta, as revealed by the induction of a temperature-dependent hypersensitive response in the non-host plant Arabidopsis thaliana Col-0. Our results show that, in the arms race between plants and bacteria, the temperature-dependent timing of bacterial virulence versus the induction of plant defenses is probably one of the fundamental parameters governing the outcome of the interaction.
