Project description:The goals of this study are to compare NGS-derived transcriptome profiling (RNA-seq) from grapevine wood infected by a fungal pathogen in the presence of a root biological control agent. One of the goals was to obtain molecular data about the fungus pathogen (Phaeomoniella chlamydospora) during grapevine wood infection. Grapevine pathogen-infected wood mRNA profiles of 2-month-old plantlets (14 days post infection) were generated by deep sequencing, in triplicate, using Illumina Hiseq2500. The sequence reads that passed quality filters were analyzed by TopHat followed by Cufflinks. qRTaPCR validation was performed using SYBR Green assays. Using an optimized data analysis workflow, we mapped sequence reads to the grapevine genome (build IGGP 12x) and identified pathogen transcripts. RNAseq analyses, using a ribosomal RNA depletion technology for library preparation, provided identification of genes expressed by P. chlamydospora during infection: as for genes related to effector biosynthesis enzymes, carbohydrate-active enzymes and transcription regulators involved in known regulation pathways in fungi. Insights about P. oligandrum modulation of grapevine infection by this pathogen were also found. Our study represents the first detailed analysis of grapevine wood infection by a fungal pathogen generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that NGS offers a comprehensive evaluation of mRNA content within grapevine wood tissue. We conclude that RNA-seq based transcriptome characterization would permit the dissection of complex biologic interactions.
Project description:Fomitiporia mediterranea (Fmed) is one of the main fungal species found in grapevine wood rot, also called “amadou”, one of the most typical symptoms of grapevine trunk disease Esca. This fungus is functionally classified as a white-rot, able to degrade all wood structure polymers, i.e., hemicelluloses, cellulose, and the most recalcitrant component, lignin. Specific enzymes are secreted by the fungus to degrade those components, namely carbohydrate active enzymes for hemicelluloses and cellulose, which can be highly specific for given polysaccharide, and peroxidases, which enable white-rot to degrade lignin, with specificities relating to lignin composition as well. Furthermore, besides polymers, a highly diverse set of metabolites often associated with antifungal activities is found in wood, this set differing among the various wood species. Wood decayers possess the ability to detoxify these specific extractives and this ability could reflect the adaptation of these fungi to their specific environment. The aim of this study is to better understand the molecular mechanisms used by Fmed to degrade wood structure, and in particular its potential adaptation to grapevine wood. To do so, Fmed was cultivated on sawdust from different origins: grapevine, beech, and spruce. Carbon mineralization rate, mass loss, wood structure polymers contents, targeted metabolites and secreted proteins were measured. We used the well-known white-rot model Trametes versicolor for comparison. Whereas no significant degradation was observed with spruce, a higher mass loss was measured on Fmed grapevine culture compared to beech culture. Moreover, on both substrates, a simultaneous degradation pattern and the degradation of wood extractives were demonstrated, and proteomic analyses identified a relative overproduction of oxidoreductases involved in lignin and extractive degradation on grapevine cultures, and only few differences in carbohydrate active enzymes. These results could explain at least partially the adaptation of Fmed to grapevine wood structural composition compared to other wood species and suggest that other biotic and abiotic factors should be considered to fully understand the potential adaptation of Fmed to its ecological niche.
Project description:Cultivated grapevine (Vitis vinifera) is susceptible to many pathogens which cause significant losses to viticulture worldwide. Chemical control is available, but agro-ecological concerns have raised interest in alternative methods, especially in elicitation of plant immunity by bio-molecules such as Pathogen Associated Molecular Patterns (PAMPs). We have demonstrated that the beta-glucan laminarin (Lam) and its sulfated derivative (PS3) induce a PAMP-triggered immunity in grapevine against downy mildew (Plasmopara viticola). However, if Lam elicits classical grapevine defenses, PS3 triggered grapevine resistance via a poorly understood priming phenomenon. The aim of this study was to discover the mechanism of the PS3-induced resistance. On uninfected grapevine, we first investigated defense signaling and performed microarray experiments to identify early events and genes directly triggered by PS3. Our results showed that PS3 i) was unable to elicit ROS and NO production, cytosolic Ca2+ variations, MAPK activation but triggered a long lasting plasma membrane depolarization in grapevine cells ii) up-regulated a stress-responsive transcriptome close to the one induced by Lam but only partly overlapping the ones triggered by salicylate (SA) or jasmonate (JA). Finally, in response to P. viticola infection, PS3 specifically primed the SA- and ROS-dependent defense pathways leading to grapevine triggered immunity against this biotroph. Keywords: cell death, induced resistance, oomycete, priming, reactive oxygen species, salicylate, sulfated laminarin, transcriptomics, Vitis vinifera. 6 samples (Adj, PS3, Lam, ctrl, SA, JA) were analized with 3 biological replicates each, Adj and ctrl samples are reference samples
Project description:Cultivated grapevine (Vitis vinifera) is susceptible to many pathogens which cause significant losses to viticulture worldwide. Chemical control is available, but agro-ecological concerns have raised interest in alternative methods, especially in elicitation of plant immunity by bio-molecules such as Pathogen Associated Molecular Patterns (PAMPs). We have demonstrated that the beta-glucan laminarin (Lam) and its sulfated derivative (PS3) induce a PAMP-triggered immunity in grapevine against downy mildew (Plasmopara viticola). However, if Lam elicits classical grapevine defenses, PS3 triggered grapevine resistance via a poorly understood priming phenomenon. The aim of this study was to discover the mechanism of the PS3-induced resistance. On uninfected grapevine, we first investigated defense signaling and performed microarray experiments to identify early events and genes directly triggered by PS3. Our results showed that PS3 i) was unable to elicit ROS and NO production, cytosolic Ca2+ variations, MAPK activation but triggered a long lasting plasma membrane depolarization in grapevine cells ii) up-regulated a stress-responsive transcriptome close to the one induced by Lam but only partly overlapping the ones triggered by salicylate (SA) or jasmonate (JA). Finally, in response to P. viticola infection, PS3 specifically primed the SA- and ROS-dependent defense pathways leading to grapevine triggered immunity against this biotroph. Keywords: cell death, induced resistance, oomycete, priming, reactive oxygen species, salicylate, sulfated laminarin, transcriptomics, Vitis vinifera.
Project description:Transcriptional changes occurring at the infection site of 2 weeks old Cabernet sauvignon grapevine cuttings infected with a wood pathogen (Phaeomoniella chlamydospora) in the presence of a root-inoculated biocontrol agent (Pythium oligandrum). Gene expression profiling was done using the Nimblegen whole genome array with 3 biological replicates of 3 pooled wood chunks harvested 0 and 14 d after treatment (pathogen infection, biocontrol agent inoculation, mock treatment).
Project description:Transcriptome profiling by RNA sequencing determined the genome-wide patterns of expression of N. parvum virulence factors when PDA or grape wood were provided as nutrient source and during an extensive interaction time course with grapevine stem.
Project description:The fungal response to compositional differences in softwood as measured by transcriptomics, proteomics and enzyme activities showed a partial tailoring to wood composition.
Project description:Despite rapid progress in characterizing transcription factor-driven reprogramming of somatic cells to an induced pluripotent stem (iPS) cell state, many mechanistic questions still remain. To gain insight into the earliest events in the reprogramming process, we systematically analyzed the transcriptional and epigenetic changes that occur during early factor induction after discrete numbers of divisions. We observed rapid, genome-wide changes in the euchromatic histone modification, H3K4me2, at more than a thousand loci including large subsets of pluripotency or developmentally related gene promoters and enhancers. In contrast, patterns of the repressive H3K27me3 modification remained largely unchanged except for focused depletion specifically at positions where H3K4 methylation is gained. These chromatin regulatory events precede transcriptional changes within the corresponding loci. Our data provide evidence for an early, organized, and population-wide epigenetic response to ectopic reprogramming factors that clarify the temporal order through which somatic identity is reset during reprogramming. Genome-scale DNA methylation was measured by reduced representation bisulfite sequencing (RRBS) during the initial phase in the reprogramming of mouse embryonic fibroblasts.