Project description:The plant pathogenic fungus Fusarium graminearum (Fgr) creates economic and health risks in cereals agriculture. Fgr causes head blight (or scab) of wheat and stalk rot of corn, reducing yield, degrading grain quality and polluting downstream food products with mycotoxins. Fungal plant pathogens must secrete proteases to access nutrition and to breakdown the structural protein component of the plant cell wall. Research into the proteolytic activity of Fgr is hindered by the complex nature of the suite of proteases secreted. We used a systems biology approach comprising genome analysis, transcriptomics and label-free quantitative proteomics to characterise the peptidases deployed by Fgr during growth. A combined analysis of published microarray transcriptome datasets revealed seven transcriptional groupings of peptidases based on in vitro growth, in planta growth, and sporulation behaviours. An orbitrap MS/MS proteomics technique defined the extracellular proteases secreted by Fusarium graminearum.
Project description:Salicylic acid (SA) is one of the key signal molecules in regulating plant resistance to diverse pathogens. It is predominantly associated with resistance against biotrophic and hemibiotrophic pathogens, and triggering systemic acquired resistance (SAR) in Arabidopsis. However, whether and how SA directly affects Fusarium graminearum and how SA influences the defence efficiency of wheat against fusarium head blight (FHB) are still poorly understood. Previous experiments have shown that the growth of F. graminearum mycelia and the germination of spores were significantly inhibited, and eventually stopped by increasing amounts of SA in both liquid and solid media cultures. Co-inoculation of SA and Fg spores has led to reduced FHB symptoms in the very susceptible Triticum aestivum cultivar ‘Roblin’. To better understand the effect of SA on F. graminearum mycelial growth, we have compared the expression profiles of SA-treated and untreated F. graminearum liquid cultures after 8 and 24 h of treatment, using an F. graminearum custom-commercial microarray. The microarray analysis suggests that F. graminearum can metabolize SA through two pathways, the gentisate and catechol pathways that are present in many fungal species. Additional experiments have confirmed the capacity of F. graminearum to metabolize SA. Our results demonstrate that, although F. graminearum has the capacity to metabolize SA, SA has a significant and direct impact on F. graminearum through a reduction in efficiency of germination and growth at higher concentrations.
Project description:Salicylic acid (SA) is one of the key signal molecules in regulating plant resistance to diverse pathogens. It is predominantly associated with resistance against biotrophic and hemibiotrophic pathogens, and triggering systemic acquired resistance (SAR) in Arabidopsis. However, whether and how SA directly affects Fusarium graminearum and how SA influences the defence efficiency of wheat against fusarium head blight (FHB) are still poorly understood. Previous experiments have shown that the growth of F. graminearum mycelia and the germination of spores were significantly inhibited, and eventually stopped by increasing amounts of SA in both liquid and solid media cultures. Co-inoculation of SA and Fg spores has led to reduced FHB symptoms in the very susceptible Triticum aestivum cultivar ‘Roblin’. To better understand the effect of SA on F. graminearum mycelial growth, we have compared the expression profiles of SA-treated and untreated F. graminearum liquid cultures after 8 and 24 h of treatment, using an F. graminearum custom-commercial microarray. The microarray analysis suggests that F. graminearum can metabolize SA through two pathways, the gentisate and catechol pathways that are present in many fungal species. Additional experiments have confirmed the capacity of F. graminearum to metabolize SA. Our results demonstrate that, although F. graminearum has the capacity to metabolize SA, SA has a significant and direct impact on F. graminearum through a reduction in efficiency of germination and growth at higher concentrations. Untreated and Salicylic Acid (SA) treated liquid cultures of F. graminearum at 8h and 24h collection times. Three biological replicates per time point and treatment, 2 technical replicates (dye flips) per sample.
Project description:【Objective】 The objective of this study is to study the transcriptome regulation mechanism of F. graminearum under different pH stress conditions, analyze the gene expression level and its differences, and explore the metabolic pathways related to the anti-stress response of F. graminearum cells under acidic or alkaline conditions, and reveal how F. graminearum actively regulates intracellular metabolism and synthesis processes to adapt to the changes of extracellular pH environment. 【Method】 F. graminearum was cultured in PDB (potato dextrose broth) medium with initial pH of 4.5, 6.5 and 8.0 for 48 h, and the total RNA of the strain was extracted to construct a cDNA library. Transcriptome sequencing and bioinformatics techniques were used to identify the related differentially expressed genes (DEGs), and the metabolic pathways involved were further analyzed. 【Result】 A total of 4283 DEGs were detected under acidic conditions, of which 2232 were up-regulated and 2252 were down-regulated. Under alkaline conditions, there were a total of 498 DEGs, of which 269 were up-regulated and 229 were down-regulated. The results of Gene Ontology (GO) functional enrichment analysis showed that 211 GO terms were significantly enriched and 72 were down-regulated under acidic conditions. There were 33 GO terms that were revised upwards and 40 downwards under alkaline conditions. The results of KEGG encyclopedia of genes and Genomes (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis showed that 22 pathways were significantly enriched and 32 pathways were down-regulated under acidic conditions. There were 8 up-regulated pathways and 13 down-regulated pathways under alkaline conditions. The expression of membrane transporters and hydrolysis of carbohydrate compounds and other related genes were up-regulated, and the expression of genes related to protein metabolism was down-regulated, which assisted F. graminearum cells to adapt to changes in the external environment. At the same time, F. graminearum maintained the internal environment balance of its own cells by reducing secondary metabolism and amino acid metabolism under acidic and alkaline conditions, respectively, so as to resist extracellular pH stress. 【Conclusion】 In the acidic environment, Fusarium graminearum adapts to the changes in the extracellular environment by promoting the production of riboprotein complexes and secondary metabolism. In an alkaline environment, Fusarium graminearum cells respond to and sense external stresses through amino acid metabolism. The analysis of the metabolic pathways of F. graminearum cells provides important gene expression data for the response of F. graminearum to different pH environments, and the results of this study are helpful to understand the pathogenesis of F. graminearum.