Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease. The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana, and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/P. parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy. The present project aims at analyzing the compatible interaction between A. thaliana roots and P. parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom-designed P. parasitica biochip will enable analyzing of P. parasitica gene expression during the same stages.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease. The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana, and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/P. parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy. The present project aims at analyzing the compatible interaction between A. thaliana roots and P. parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom-designed P. parasitica biochip will enable analyzing of P. parasitica gene expression during the same stages. 10 samples were used in this experiment.
Project description:Phytophthora infestans is most notorious oomycete causing a devastating disease on tomato called late blight. The molecular mechanisms involved in host-parasite interaction is still unexplored well. Investigation of changes in gene expression profile after pathogen infection to find out the mechanisms involved in infection process
Project description:Phytophthora infestans is most notorious oomycete causing a devastating disease on tomato called late blight. The molecular mechanisms involved in host-parasite interaction is still unexplored well. Investigation of changes in gene expression profile after pathogen infection to find out the mechanisms involved in infection process Second full expanded leaves from both healthy tomato plants (non-inoculated) and diseased tomato plants inoculated with Phytophthora infestans inoculum were used to extract total RNA for microarry analysis 12 hours post inoculation time.
Project description:Oomycete cells are surrounded by a polysaccharide rich cell wall matrix that, in addition to being essential for cell growth, also functions as protective ”armour”. It follows, that the enzymes responsible for the synthesis of the cell wall provide potential targets for disease management. Interestingly, the oomycete cell wall enzymes are predicted to be plasma membrane proteins. In this project, we used a quantitative (iTRAQ) mass spectrometry-based proteomics approach to characterize the plasma membrane proteome of the hyphal cells of S. parasitica, providing the first complete plasma membrane proteome of an oomycete species. Of significance, is the identification of proteins enriched in functional microdomains (Detergent-Resistant Microdomains; DRMs). In silico analysis showed that DRM-enriched proteins are mainly involved in both molecular transport and β-1,3-glucan synthesis, potentially contributing to post infection pathogenesis.
Project description:Within oomycetes, Phytophthora is a genus of eukaryotic microorganisms encompassing some of the most damaging plant pathogens. It spreads by airborne sporangia or waterborne zoospores. Zoospores perceive plant signals through chemotaxis and electrotaxis, and produce signals to attract other zoospores (autotaxis), resulting in auto-aggregation or biofilm formation on the plant surface. The mechanisms underlying intercellular communication and consequent attraction, adhesion and aggregation are largely unknown. Recent studies demonstrated that in Phytophthora parasitica the perception of K+ gradient induced coordinated motion and rapid aggregation. Based on this model, we combined data mining and ultrastructural microscopy analyses to propose a first definition of molecular events leading to oomycete aggregation. Results indicate that the transcriptome repertoire required for aggregation is fully functional already at this single zoospore stage, before aggregation or encystment. Freely swimming zoospores secrete or harbor proteins implied in aggregation through adhesion and extracellular matrix elaboration. They secrete vesicular and fibrillary material, including fibronectin-like proteins, resulting in intercellular structure formation. Consistently, the signature of transcriptome dynamics during transition from single-cell to aggregate is an upregulation of genes contributing to vesicular trafficking, possibly involved in adhesive proteins and extracellular matrix components mobilization. Moreover, the transcriptome signature suggests that pH homeostasis may contribute to aggregation by acting on both zoospore movement and adhesion.
Project description:The oomycete Phytophthora palmivora infects a wide range of tropical crops worldwide. Like other filamentous plant pathogens, it secretes effectors to colonise plant tissues. Here we characterise FIRE, an RXLR effector that contains a canonical mode I 14-3-3 phospho-sensor binding motif that is conserved in effectors of several Phytophthora species. FIRE is phosphorylated in planta and interacts with multiple 14-3-3 proteins. Binding is sensitive to the R18 14-3-3 inhibitor. FIRE promotes plant susceptibility and co-localises with its target around haustoria. This work uncovers a new type of oomycete effector target mechanism. It demonstrates that substrate mimicry for 14-3-3 proteins is a cross-kingdom effector strategy used by both prokaryotic and eukaryotic plant pathogens to suppress host immunity.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease.The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/Phytophthora parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy.The present project aims at analyzing the compatible interaction between A. thaliana roots and Phytophthora parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom designed Phytophthora parasitica biochip will enable analyzing of Phytophthora parasitica gene expression during the same stages. The pathosystem involving A. thaliana and Phytophthora parasitica was described in Attard A, Gourgues M, Callemeyn-Torre N, Keller H. 2010. The New phytologist 187: 449–460. The protocol for recovery of RNA from purified appressoria was described in Kebdani N, Pieuchot L, Deleury E, Panabieres F, Le Berre JY, Gourgues M. 2010. New Phytol 185: 248–257.
Project description:Interactions between pathogenic oomycetes and microbiota residing on the surface of the host plant root are unknown, despite being critical to inoculum constitution. The nature of these interactions was explored for the polyphagous and telluric species Phytophthora parasitica.Composition of the rhizospheric microbiota of Solanum lycopersicum was characterized using deep re-sequencing of 16S rRNA gene to analyze tomato roots either free of or partly covered with P. parasitica biofilm. Colonization of the host root surface by the oomycete was associated with a shift in microbial community involving a Bacteroidetes/Proteobacteria transition and Flavobacteriaceae as the most abundant family. Identification of members of the P. parasitica-associated microbiota interfering with biology and oomycete infection was carried out by screening for bacteria able to (i) grow on a P. parasitica extract-based medium (ii), exhibit in vitro probiotic or antibiotic activity towards the oomycete (iii), have an impact on the oomycete infection cycle in a tripartite interaction S. lycopersicum-P. parasitica-bacteria. One Pseudomonas phylotype was found to exacerbate disease symptoms in tomato plants. The lack of significant gene expression response of P. parasitica effectors to Pseudomonas suggested that the increase in plant susceptibility was not associated with an increase in virulence. Our results reveal that Pseudomonas spp. establishes commensal interactions with the oomycete. Bacteria preferentially colonize the surface of the biofilm rather than the roots, so that they can infect plant cells without any apparent infection of P. parasitica.The presence of the pathogenic oomycete P. parasitica in the tomato rhizosphere leads to a shift in the rhizospheric microbiota composition. It contributes to the habitat extension of Pseudomonas species mediated through a physical association between the oomycete and the bacteria.