Dataset Information

RetS-Mediated Environmental Sensing Coordinates TetR-Dependent Regulation of Type III Secretion System and Virulence in Pseudomonas syringae pv. actinidiae

ABSTRACT: Kiwifruit bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), is an emerging global concern in kiwifruit production. Successful Psa infection in kiwifruit relies on the type III secretion system (T3SS), which is governed by the HrpR/S-HrpL regulatory pathway. However, the mechanisms by which certain transcriptional factors regulate this pathway remain poorly understood. In this study, we identified the TetR/AcrR family transcription factors C_22735 (tetR1) and C_04700 (hybrid histidine kinase; retS) in the P. syringae pv. actinidiae (biovar 3) strain S26 using transposon libraries and a DNA pull-down strategy. Both the mutant strains tetR1 and retS exhibited significantly reduced pathogenicity in kiwifruit leaf discs and a diminished ability to induce hrpRS, hrpL, and hrpA expression in vitro and showed a reduced hypersensitive response in Nicotiana benthamiana. Moreover, transcriptomic studies showed a considerable overlap in down-regulated genes between the tetR1 and two-component system (TCS) retS mutant, highlighting the intertwined regulatory roles of both genes. This overlap suggests a tightly coordinated regulatory system, where tetR1 serves as the response regulator of the hybrid histidine kinase retS to regulate T3SS and virulence. The electrophoretic mobility shift assays, and luciferase-based promoter activity detection further revealed that TetR1 positively regulates the T3SS by directly binding to the promoter regions of hrpR/S and hrpL. This study identifies the tetR1 gene as the first TetR-family transcription factor directly linking the hybrid TCS retS to HrpR/S-HrpL -mediated T3SS regulatory pathway activation in Psa for regulation.

ORGANISM(S): Pseudomonas syringae pv. actinidiae

PROVIDER: GSE286487 | GEO | 2025/01/31

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Background Dickeya dadantii is a necrotrophic pathogen causing disease in many plants. Previous studies have demonstrated that the type III secretion system (T3SS) of D. dadantii is required for full virulence. HrpL is an alternative sigma factor that binds to the hrp box promoter sequence of T3SS genes to up-regulate their expression. Methodology/Principal Findings To explore the inventory of HrpL-regulated genes of D. dadantii 3937 (3937), transcriptome profiles of wild-type 3937 and a hrpL mutant grown in a T3SS-inducing medium were examined. Using a cut-off value of 1.5, significant differential expression was observed in sixty-three genes, which are involved in various cellular functions such as type III secretion, chemotaxis, metabolism, regulation, and stress response. A hidden Markov model (HMM) was used to predict candidate hrp box binding sites in the intergenic regions of 3937, including the promoter regions of HrpL-regulated genes identified in the microarray assay. In contrast to biotrophic phytopathgens such as Pseudomonas syringae, among the HrpL up-regulated genes in 3937 only those within the T3SS were found to contain a hrp box sequence. Moreover, direct binding of purified HrpL protein to the hrp box was demonstrated for hrp box-containing DNA fragments of hrpA and hrpN using the electrophoretic mobility shift assay (EMSA). In this study, a putative T3SS effector DspA/E was also identified as a HrpL-upregulated gene, and shown to be translocated into plant cells in a T3SS-dependent manner. Conclusion/Significances We provide the genome-wide study of HrpL-regulated genes in a necrotrophic phytopathogen (D. dadantii 3937) through a combination of transcriptomics and bioinformatics, which led to identification of several effectors. Our study indicates the extent of differences for T3SS effector protein inventory requirements between necrotrophic and biotrophic pathogens, and may allow the development of different strategies for disease control for these different groups of pathogens. Analysis used aerobic steady state RNA from wild-type as control samples for comparison to the experimental samples of hrpL mutant taken 6 h post-inoculation in T3SS inducible minimum media. The microarray results are based on the geomean of ten normalized expression values derived from three biological replicates and two dye-swap experiments with a technology replicate for each array.

Dataset Information

RetS-Mediated Environmental Sensing Coordinates TetR-Dependent Regulation of Type III Secretion System and Virulence in Pseudomonas syringae pv. actinidiae

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets