Integration of Transcriptomic and Proteomic Approaches Reveals the Temperature-Dependent Virulence of Pseudomonas plecoglossicida

Abstract

Pseudomonas plecoglossicida is a facultative pathogen that is associated with diseases of multiple fish, mainly at 15–20°C. Although fish disease caused by P. plecoglossicida has led to significant economic losses, the mechanisms of the temperature-dependent virulence are unclear. Here, we identify potential pathogenicity mechanisms and demonstrate the direct regulation of several virulence factors by temperature with transcriptomic and proteomic analyses, quantitative real-time PCR (qRT-PCR), RNAi, pyoverdine (PVD) quantification, the chrome azurol S (CAS) assay, growth curve measurements, a biofilm assay, and artificial infection. The principal component analysis, the heat map generation and hierarchical clustering, together with the functional annotations of the differentially expressed genes (DEGs) demonstrated that, under different growth temperatures, the animation and focus of P. plecoglossicida are quite different, which may be the key to pathogenicity. Genes involved in PVD synthesis and in the type VI secretion system (T6SS) are specifically upregulated at the virulent temperature of 18°C. Silencing of the PVD-synthesis-related genes reduces the iron acquisition, growth, biofilm formation, distribution in host organs and virulence of the bacteria. Silencing of the T6SS genes also leads to the reduction of biofilm formation, distribution in host organs and virulence. These findings reveal that temperature regulates multiple virulence mechanisms in P. plecoglossicida, especially through iron acquisition and T6SS secretion. Meanwhile, integration of transcriptomic and proteomic data provide us with a new perspective into the pathogenesis of P. plecoglossicida, which would not have been easy to catch at either the protein or mRNA differential analyses alone, thus illustrating the power of multi-omics analyses in microbiology.

Transcriptomics in aquaculture: current status and applications

“…Recently, a combined analysis of both transcriptomics and proteomics are applied to unravel the molecular mechanisms of various bacterial and viral infections (Huang et al . ; Liu et al . ; Yue et al .…”

“…Huang et al . () applied this combined strategy to study the temperature dependent virulence of facultative fish pathogen Pseudomonas plecoglossicida . To understand the mechanism of the thermo‐linked epizootics, Yue et al .…”

A metabolomic investigation into the temperature‐dependent virulence of Pseudomonas plecoglossicida from large yellow croaker (Pseudosciaena crocea)

“…Water temperature is considered to be the most important environmental factor affecting the P. plecoglossicida induced “white spots disease” (Huang, Liu et al, ). In P. crocea farms, the disease often outbreaks between April and May, when water temperature is about 16–19°C (Tao, Zhou, Zhou, & Wang, ).…”

“…In P. crocea farms, the disease often outbreaks between April and May, when water temperature is about 16–19°C (Tao, Zhou, Zhou, & Wang, ). Artificial infection of P. crocea and E. coioides with P. plecoglossicida caused signs in the internal organs at 16–19°C but not at 7–12°C and 24–28°C (Huang, Liu et al, ). Virulence genes associated with iron uptake and toxin secretion were significantly up‐regulated in P. plecoglossicida at virulent temperature (18°C).…”

“…Virulence genes associated with iron uptake and toxin secretion were significantly up‐regulated in P. plecoglossicida at virulent temperature (18°C). Meanwhile, the iron acquisition, growth, distribution in host organs, biofilm formation and pathogenicity of P. plecoglossicida were also promoted at virulent temperature (Huang, Liu et al, ). However, mechanisms underlying the temperature‐dependent pathogenicity of P. plecoglossicida are still limited and incomplete.…”