Project description:Z. tritici is a fungal pathogen causing the disease septoria tritici blotch, one of the most economically devastating foliar diseases in wheat. The molecular basis underlying Z. tritici growth, development and pathogenicity is not fully understood yet. Compared to the genomic investigations in this fungus, little is known about the protein expression at a systematic level. The aim of the project is to construct a comprehensive protein database of Z. tritici growing in nutrient-limiting and rich media and in vivo at a late stage of wheat infection by using 1D gel-based and SCX-based proteomics and subproteomics (intracellular and extracellular) approaches.
Project description:Septoria leaf blotch is a worldwide threat for wheat and mainly controlled by the application of synthetic fungicides. The fungal pathogen responsible for this disease, Zymoseptoria tritici, was shown as highly adaptable to its host plant, but also to fungicide challenge. Over the past decades it developed resistance to most fungicides due to target site modifications. Recently isolated strains showed cross-resistance to diverse fungicides and to unrelated drugs, suggesting a resistance mechanism that seems rarer in phytopathogenic fungi, known as multidrug resistance (MDR) in other organisms. In this study we show for two Z. tritici MDR strains, MDR6 and MDR7, enhanced prochloraz efflux sensitive to the modulators amitryptiline and chlorpromazine. Efflux was also inhibited by verapamil in the MDR7strain. Transcriptomics revealed several overexpressed transporter genes in both MDR strains, out of which the expression of the MgMFS1 transporter gene was the strongest and constitutively high in tested MDR field strains. Its inactivation in the MDR6 strain abolished resistance to fungicides with different modes of action revealing its involvement in the MDR phenomenon in Z. tritici.
Project description:Septoria leaf blotch is a worldwide threat for wheat and mainly controlled by the application of synthetic fungicides. The fungal pathogen responsible for this disease, Zymoseptoria tritici, was shown as highly adaptable to its host plant, but also to fungicide challenge. Over the past decades it developed resistance to most fungicides due to target site modifications. Recently isolated strains showed cross-resistance to diverse fungicides and to unrelated drugs, suggesting a resistance mechanism that seems rarer in phytopathogenic fungi, known as multidrug resistance (MDR) in other organisms. In this study we show for two Z. tritici MDR strains, MDR6 and MDR7, enhanced prochloraz efflux sensitive to the modulators amitryptiline and chlorpromazine. Efflux was also inhibited by verapamil in the MDR7strain. Transcriptomics revealed several overexpressed transporter genes in both MDR strains, out of which the expression of the MgMFS1 transporter gene was the strongest and constitutively high in tested MDR field strains. Its inactivation in the MDR6 strain abolished resistance to fungicides with different modes of action revealing its involvement in the MDR phenomenon in Z. tritici. A total of four strains were compared, two sensitive (IPO323, S6) and two MDR strains (09-ASA-3apz; 09-CB01) with three replicates each. All strains were grown in liquid YPD medium to exponential growth.
Project description:The hemibiotrophic fungus Zymoseptoria tritici causes Septoria tritici blotch disease of wheat (Triticum aestivum). Pathogen reproduction on wheat occurs without cell penetration, suggesting that dynamic and intimate intercellular communication occurs between fungus and plant throughout the disease cycle. We used deep RNA sequencing and metabolomics to investigate the physiology of plant and pathogen throughout an asexual reproductive cycle of Z. tritici on wheat leaves. Over 3,000 pathogen genes, more than 7,000 wheat genes, and more than 300 metabolites were differentially regulated. Intriguingly, individual fungal chromosomes contributed unequally to the overall gene expression changes. Early transcriptional down-regulation of putative host defense genes was detected in inoculated leaves. There was little evidence for fungal nutrient acquisition from the plant throughout symptomless colonization by Z. tritici, which may instead be utilizing lipid and fatty acid stores for growth. However, the fungus then subsequently manipulated specific plant carbohydrates, including fructan metabolites, during the switch to necrotrophic growth and reproduction. This switch coincided with increased expression of jasmonic acid biosynthesis genes and large-scale activation of other plant defense responses. Fungal genes encoding putative secondary metabolite clusters and secreted effector proteins were identified with distinct infection phase-specific expression patterns, although functional analysis suggested that many have overlapping/redundant functions in virulence. The pathogenic lifestyle of Z. tritici on wheat revealed through this study, involving initial defense suppression by a slow-growing extracellular and nutritionally limited pathogen followed by defense (hyper) activation during reproduction, reveals a subtle modification of the conceptual definition of hemibiotrophic plant infection.
Project description:We collected infected wheat leaf material at up to nine time points per Z. tritici isolate and conducted confocal microscopy analyses to select samples for RNA extraction and transcriptome sequencing based on the morphological infection stage. Thereby, we generated stage-specific RNA-seq datasets corresponding to the four core infection stages allowing us to compare the isolate-specific expression profiles at the same developmental stage of infection. Our final dataset comprises four stage-specific transcriptomes per isolate with two biological replicates per sample. Comparative transcriptome analyses reveal that the expression phenotypes of the three isolates differ significantly.
Project description:We have applied whole transcriptome profiling to infer genetic determinants of pathogenicity and host specialization in Z. tritici. Our data includes RNAseq data from early infection stages of a compatible (wheat) and a non-compatible host (Brachypodium distachyon). Overall transcription of AC genes is remarkably lower than genes on core chromosomes (CC) and only 40% of the genes are transcribed. We identify 31 AC and 1069 CC genes showing plant specific expression. In addition 21 CC genes are only upregulated in wheat supporting functional relevance in host specificity. We further explore the genomic composition and distribution of unique and paralogous genes in Z. tritici focusing on the evolutionary origin of AC genes. In contrast to previous studies we show that ACs mainly encode unique genes. Phylogenetic analyses suggest that rare duplication events in the Z. tritici genome precede diversification of Zymoseptoria species and demonstrate that ACs have been maintained in the genome of Zymoseptoria over long evolutionary times. Examination of gene expression at 3 different growth condition of the wheat pathogen Z. tritici.
Project description:<p>Rhamnolipids (RLs), glycolipids biosynthesized by the <em>Pseudomonas</em> and <em>Burkholderia</em> genera, are known to display various activities against a wide range of pathogens. Most previous studies on RLs focused on their direct antimicrobial activity, while only a few reports described the mechanisms by which RLs induce resistance against phytopathogens and the related fitness cost on plant physiology. Here, we combined transcriptomic and metabolomic approaches to unravel the mechanisms underlying RL-induced resistance in wheat against the hemibiotrophic fungus <em>Zymoseptoria tritici</em>, a major pathogen of this crop. Investigations were carried out by treating wheat plants with a bioinspired synthetic mono-RL with a 12-carbon fatty acid tail, dodecanoyl α/β-L-rhamnopyranoside (Rh-Est-C12), under both infectious and non-infectious conditions to examine its potential wheat defense-eliciting and priming bioactivities. Whereas, Rh-Est-C12 conferred to wheat a significant protection against <em>Z. tritici</em> (41% disease severity reduction), only a slight effect of this RL on wheat leaf gene expression and metabolite accumulation was observed. A subset of 24 differentially expressed genes (DEGs) and 11 differentially accumulated metabolites (DAMs) was scored in elicitation modalities 2, 5 and 15 days post-treatment (dpt), and 25 DEGs and 17 DAMs were recorded in priming modalities 5 and 15 dpt. Most changes were down-regulations, and only a few DEGs and DAMs associated with resistance to pathogens were identified. Nevertheless, a transient early regulation in gene expression was highlighted at 2 dpt (e.g., genes involved in signaling, transcription, translation, cell-wall structure and function), suggesting a perception of the RL by the plant upon treatment. Further <em>in vitro</em> and <em>in planta</em> bioassays showed that Rh-Est-C12 displays a significant direct antimicrobial activity toward <em>Z. tritici</em>. Taken together, our results suggest that Rh-Est-C12 confers protection to wheat against <em>Z. tritici</em> through direct antifungal activity and, to a lesser extent, by induction of plant defenses without causing major alterations in plant metabolism. This study provides new insights into the modes of action of RLs on the wheat-<em>Z. tritici</em> pathosystem and highlights the potential interest in Rh-Est-C12, a low-fitness cost molecule, to control this pathogen.</p>