Project description:Transcriptome sequencing is a powerful approach to globally delineate both the transcriptional and post-transcriptional genome regulation in human and other higher eukaryotes. This study sequenced the transcriptomes of two pathogenicity-differential strains of the plant wilt pathogen Verticillium dahliae. Although they showed no growth difference in vitro, hundreds of V. dahliae genes including those synthesizing aflatoxin were preferentially expressed at in the high-virulence strain. Using both the Pfam and GO annotation strategies, some of these putative virulence genes were ambiguously clustered into several known pathogenic mechanisms including hydrophobins secreted from fungal cells and acting as phytotoxin, biosynthesis of melanin protecting the fungal pathogen against host immune responses, membrane proteins of CFEM and major facilitator superfamily MFS1 with known functions in pathogenesis and multi-drug resistance, respectively. These results suggest that some pathogenicity pathways are pre-activated at the transcriptional level prior to the fungal infection of host plants. We developed two algorithms to confidently identify 1518 alternative splicing events in 1,259 Verticillium genes, representing 15.1% of multi-exonic genes. Among the events, 43.5% involving in novel splice sites were classified into nine AS types, the others belong to intron retention. Verticillium AS genes were exclusively enriched in the regulatory biological processes such as mycelium development, reproduction, morphogenesis, cell communication and signal transduction, predicting a primary function of AS regulation when the pathogen infecting its host. This work presents a transcriptome-wide approach for identifying the fungal virulence genes and pathogenicity mechanisms; both the methodology and mechanisms could be generally applicable to other fungal pathogens.
Project description:A first line of defense against pathogen infections is the recognition of pathogen-associated molecular patterns (PAMPs), leading to PAMP-triggered immunity (PTI). MicroRNAs (miRNAs) are primarily known as central regulators of plant development, but a few have also been connected to immunity. We have found that several fungal pathogens lead to a reduction in miR396 levels, suggesting that miR396 are negative regulators of downstream defense responses. In agreement with such as scenario, constitutive attenuation of miR396 activity enhances resistance to infection by fungal pathogens, while increased miR396 activity reduces pathogen resistance. We conclude that constitutive reduction of miR396 levels confer a primed state for enhanced defense reactions
Project description:Bivalent chromatin modification containing opposing H3K4me3 and H3K27me3 marks controls various biological processes by fine-tuning gene expression in animals and plants, however how this bivalent modification regulates pathogenicity of fungal pathogen remains exclusive. Here, we provided a genome-wide landscape of H3K4me3 and H3K27me3 of wheat head blight fungus Fusarium graminearum (Fg), leading to the identification of infection-induced bivalent chromatin-marked genes (BCGs). Among those, BCG1, which encodes a novel xylanase with a G/Q rich motif, is required for the full virulence of Fg pathogenicity through degradation of host cell wall. However, the G/Q rich motif is recognized by pattern-recognition receptors and triggers plant innate immunity. Further data illustrates that Fg employs H3K4me3 modification to induce BCG1 expression rapidly during the early infection, and then switches to bivalent H3K4me3-H3K27me3 chromatin state that renders rapid epigenetic silencing of BCG1 for escaping from host immune monitor, therefore leading to the successful invasion. Collectively, our study highlights the molecular mechanism of how fungal pathogen employs bivalent epigenetic modification to facilitate the successful infection by escaping of host immunity, which provides conceptual insights into plant-microbe interaction.
Project description:By using RNA-seq analysis on purified extracellular vesicles from the infected tissue, we found that host plant Arabidopsis thaliana secretes a panel of messenger RNAs (mRNAs) in extracellular vesicles. These mobile plant mRNAs were delivered into cells of the interacting fungal pathogen Botrytis cinerea. While using Translating Ribosome Affinity Purification (TRAP) profiling and polysome analysis, we observed that the delivered host mRNAs were associated with active fungal polysomes isolated from the infected tissue, suggesting that they are translated in the fungal cells.
Project description:A genomic insight into how an insect pest responds to the infection of a fungal insect pathogen, such as Beauveria bassiana, is critical for alternative strategy of insect pest contol based on fungal insecticides but has not been well probed. Here we constructed three pairs of digital expression libraries (transcriptomes) of Plutella xylostella (global lepidopteran pest) larvae 24, 36 and 48 hours post treatment of infection (hptI) and control (hptC) to reveal the host response to B. bassiana infection at genomic level. The paired libraries comprised 2144, 3200 and 2967 differentially expressed genes (DEGs) of P. xylostella at 24, 36 and 48 hptI/hptC, respectively. These DEGs were enriched in various immune pathways activated by the fungal infection, such as the pathways of complement and coagulation cascades, protein digestion and absorption, and drug metabolism - cytochrome P450. We found that 24 hptI was critical either for the cuticular penetration of B. bassiana or for the initial activation of the host defense system. The host immune response peaked at 36 hptI so that multiple defense mechanisms were activated against the fungal entry into the host hemocoel. At 48 hptI, many host genes involved in immunity and metabolism were downregulated, suggesting a success of fungal localization in the host hemocoel by overcoming the host defense reaction. Finally, we revealed that several fungal pathways could play important roles in the host-pathogen interaction, such as antioxidant activity, peroxidase activity and proteolysis. Up to 1636 fungal genes were co-expressed at the three time points, and 116 of them encode putative secretion proteins. Our results provide a novel insight into the pathogen-insect interaction and help to probe molecular mechanisms involved in the control of P. xylostella by B. bassiana.
Project description:A genomic insight into how an insect pest responds to the infection of a fungal insect pathogen, such as Beauveria bassiana, is critical for alternative strategy of insect pest contol based on fungal insecticides but has not been well probed. Here we constructed three pairs of digital expression libraries (transcriptomes) of Plutella xylostella (global lepidopteran pest) larvae 24, 36 and 48 hours post treatment of infection (hptI) and control (hptC) to reveal the host response to B. bassiana infection at genomic level. The paired libraries comprised 2144, 3200 and 2967 differentially expressed genes (DEGs) of P. xylostella at 24, 36 and 48 hptI/hptC, respectively. These DEGs were enriched in various immune pathways activated by the fungal infection, such as the pathways of complement and coagulation cascades, protein digestion and absorption, and drug metabolism - cytochrome P450. We found that 24 hptI was critical either for the cuticular penetration of B. bassiana or for the initial activation of the host defense system. The host immune response peaked at 36 hptI so that multiple defense mechanisms were activated against the fungal entry into the host hemocoel. At 48 hptI, many host genes involved in immunity and metabolism were downregulated, suggesting a success of fungal localization in the host hemocoel by overcoming the host defense reaction. Finally, we revealed that several fungal pathways could play important roles in the host-pathogen interaction, such as antioxidant activity, peroxidase activity and proteolysis. Up to 1636 fungal genes were co-expressed at the three time points, and 116 of them encode putative secretion proteins. Our results provide a novel insight into the pathogen-insect interaction and help to probe molecular mechanisms involved in the control of P. xylostella by B. bassiana. Here we constructed three pairs of digital expression libraries (transcriptomes) of Plutella xylostella (global lepidopteran pest) larvae 24, 36 and 48 hours post treatment of infection (hptI) and control (hptC) to reveal the host response to B. bassiana infection at genomic level
Project description:Filamentous cell growth is a vital property of fungal pathogens. The mechanisms of filamentation in the emerging multidrug-resistant fungal pathogen Candida auris are poorly understood. Here, we show that exposure of C. auris to glycerol triggers a rod-like filamentation-competent (RL-FC) phenotype, which forms elongated filamentous cells after a prolonged culture period. Whole-genome sequencing analysis reveals that all RL-FC isolates harbor a mutation in the C2H2 zinc finger transcription factor-encoding gene GFC1 (Gfc1 variants). Deletion of GFC1 leads to an RL-FC phenotype similar to that observed in Gfc1 variants. We further demonstrate that GFC1 mutation causes enhanced fatty acid β-oxidation metabolism and thereby promotes RL-FC/filamentous growth. This regulation is achieved through a Multiple Carbon source Utilizer (Mcu1)-dependent mechanism. Interestingly, both the evolved RL-FC isolates and the gfc1Δ mutant exhibit an enhanced ability to colonize the skin. Our results reveal that glycerol-mediated GFC1 mutations are beneficial during C. auris skin colonization and infection.
Project description:Host gene expression responses can be used to determine the etiology of acute infection. PBMCs were stimulated with bacterial, viral, and fungal stimuli and then analyzed for differential gene expression utilizing microarrays to derive pathogen class-specific gene expression classifiers of infection. Validation Cohort: peripheral blood samples of human patients with acute viral, bacterial, or fungal infections
Project description:Bivalent chromatin modification containing opposing H3K4me3 and H3K27me3 marks controls various biological processes by fine-tuning gene expression in animals and plants, however how this bivalent modification regulates pathogenicity of fungal pathogen remains exclusive. Here, we provided a genome-wide landscape of H3K4me3 and H3K27me3 of wheat head blight fungus Fusarium graminearum (Fg), leading to the identification of infection-induced bivalent chromatin-marked genes (BCGs). Among those, BCG1, which encodes a novel xylanase with a G/Q rich motif, is required for the full virulence of Fg pathogenicity through degradation of host cell wall. However, the G/Q rich motif is recognized by pattern-recognition receptors and triggers plant innate immunity. Further data illustrates that Fg employs H3K4me3 modification to induce BCG1 expression rapidly during the early infection, and then switches to bivalent H3K4me3-H3K27me3 chromatin state that renders rapid epigenetic silencing of BCG1 for escaping from host immune monitor, therefore leading to the successful invasion. Collectively, our study highlights the molecular mechanism of how fungal pathogen employs bivalent epigenetic modification to facilitate the successful infection by escaping of host immunity, which provides conceptual insights into plant-microbe interaction.