Design conceptuel d’un incubateur pour un nanosatellite en combinant la conception axiomatique et un index unifié de performance mécatronique (MMP)

RESUMÉ La société technique PolyOrbite de l’École Polytechnique de Montréal entreprend de concevoir un nanosatellite ayant une taille de 30cm*10cm*10cm et un poids de 4 kg, appelé ORU-S. Le lancement du satellite est prévu pour 2020 avec deux charges utiles indépendantes dont un incubateur miniaturisé. Le but de l’incubateur est de mener une expérience botanique dans l’espace afin d’étudier l’effet de la microgravité sur la croissance de la plante comestible Medicago truncatula. Depuis les années 90, les plateformes de nanosatellites ont pris de l’essor, mais les travaux de recherche effectués dans le domaine des serres miniaturisées et de la botanique spatiale restent limités. À ce jour, aucun projet n’a réussi à faire croître une plante comestible dans un nanosatellite. Ce mémoire de maîtrise présente le design conceptuel d’un incubateur miniaturisé. Cet incubateur est un laboratoire in situ qui permet la germination d’une plante en suivant et contrôlant les paramètres environnementaux pour fins de recherche scientifique. Après la validation du cahier des charges, un design conceptuel est réalisé avec plusieurs concepts potentiels en appliquant la Conception Axiomatique. En outre, à cause de la multidisciplinarité du problème de design, la détermination du « meilleur concept » est effectuée en appliquant le Profil Multicritère Mécatronique (MMP) développé par l’équipe du Prof. Achiche. La solution présentée, dans ce mémoire, est un incubateur pressurisé composé de quatre sous-systèmes : système de culture, système de contrôle de température, système d’approvisionnement et système d’inspection. Les trois premiers systèmes fournissent les conditions nécessaires à culture, soient une source d’illumination, une température convenable et une quantité satisfaisante de solutions nutritives qui permettent la croissance de la plante. Alors que le système d’inspection, il assure l’obtention et l’enregistrement des données pour les tâches de contrôle pour supporter la recherche scientifique dans ce domaine. Les travaux futurs se concentreront sur l’approfondissement de la conception optimale en utilisant des fonctions spécifiques pour résoudre des problèmes comme la gestion d’espace. Mener une expérience terrestre dans un prototype basant sur la conception sera aussi intéressant afin de vérifier la fonctionnalité du design.----------ABSTRACT The technical association PolyOrbite of École Polytechnique de Montréal is developing a nanosatellite with a size of 30cm*10cm*10cm and a weight of 4 kg, called ORU-S. This satellite will launch in 2020 with two independent payloads including a miniaturized incubator which is considered to conduct a botanical experiment in space to study the effect of microgravity on the growth of the plant Medicago truncatula. Despite the growth in popularity of the CubeSat platform from 1990, research in the areas of miniaturized greenhouses and astrobotany has been very limited. It seems that no project has made to grow a plant in space in a nanosatellite. So, this thesis presents a conceptual design of the miniaturized incubator being an in-situ laboratory that allows germination of the plant by monitoring and controlling the environmental parameters for scientific research. After the validation of the requirements specification, we implemented a preliminary design with several potential concepts by applying Axiomatic Design. In addition, because of the multidisciplinarity of the design problem, the determination of the "best concept" is carried out by applying the Multi-criteria Mechatronics Profile developed in the laboratory of Prof. Achiche. The solution presented in this thesis is a pressurized incubator consisting of four subsystems: cultivation, temperature control, supply, and inspection systems. The first three systems provide the necessary conditions for the plant: a source of illumination, a suitable temperature, and a satisfactory amount of nutrient solutions that allow the growth of the plant. As for the inspection system, it ensures data collection for control and scientific research. Future work will deepen the design using specific functions to solve problems such as space and layout management. Conducting a ground experience in a prototype based on the design will also be interesting to verify the functionality of the developed design

A phytophthora effector manipulates host histone acetylation and reprograms defense gene expression to promote infection

Immune response during pathogen infection requires extensive transcription reprogramming. A fundamental mechanism of transcriptional regulation is histone acetylation. However, how pathogens interfere with this process to promote disease remains largely unknown. Here we demonstrate that the cytoplasmic effector PsAvh23 produced by the soybean pathogen Phytophthora sojae acts as a modulator of histone acetyltransferase (HAT) in plants. PsAvh23 binds to the ADA2 subunit of the HAT complex SAGA and disrupts its assembly by interfering with the association of ADA2 with the catalytic subunit GCN5. As such, PsAvh23 suppresses H3K9 acetylation mediated by the ADA2/GCN5 module and increases plant susceptibility. Expression of PsAvh23 or silencing of GmADA2/GmGCN5 resulted in misregulation of defense-related genes, most likely due to decreased H3K9 acetylation levels at the corresponding loci. This study highlights an effective counter-defense mechanism by which a pathogen effector suppresses the activation of defense genes by interfering with the function of the HAT complex during infection

A Phytophthora sojae Glycoside Hydrolase 12 Protein Is a Major Virulence Factor during Soybean Infection and Is Recognized as a PAMP

We identified a glycoside hydrolase family 12 (GH12) protein, XEG1, produced by the soybean pathogen Phytophthora sojae that exhibits xyloglucanase and β-glucanase activity. It acts as an important virulence factor during P. sojae infection but also acts as a pathogen-associated molecular pattern (PAMP) in soybean (Glycine max) and solanaceous species, where it can trigger defense responses including cell death. GH12 proteins occur widely across microbial taxa, and many of these GH12 proteins induce cell death in Nicotiana benthamiana. The PAMP activity of XEG1 is independent of its xyloglucanase activity. XEG1 can induce plant defense responses in a BAK1-dependent manner. The perception of XEG1 occurs independently of the perception of ethylene-inducing xylanase. XEG1 is strongly induced in P. sojae within 30 min of infection of soybean and then slowly declines. Both silencing and overexpression of XEG1 in P. sojae severely reduced virulence. Many P. sojae RXLR effectors could suppress defense responses induced by XEG1, including several that are expressed within 30 min of infection. Therefore, our data suggest that PsXEG1 contributes to P. sojae virulence, but soybean recognizes PsXEG1 to induce immune responses, which in turn can be suppressed by RXLR effectors. XEG1 thus represents an apoplastic effector that is recognized via the plant’s PAMP recognition machinery.This is the publisher’s final pdf. The published article is copyrighted by the American Society of Plant Biologists and can be found at: http://www.plantcell.org/content/27/7/205

A Phytophthora sojae effector suppresses endoplasmic reticulum stress-mediated immunity by stabilizing plant Binding immunoglobulin Proteins

Phytophthora pathogens secrete an array of specific effector proteins to manipulate host innate immunity to promote pathogen colonization. However, little is known about the host targets of effectors and the specific mechanisms by which effectors increase susceptibility. Here we report that the soybean pathogen Phytophthora sojae uses an essential effector PsAvh262 to stabilize endoplasmic reticulum (ER)-luminal binding immunoglobulin proteins (BiPs), which act as negative regulators of plant resistance to Phytophthora. By stabilizing BiPs, PsAvh262 suppresses ER stress-triggered cell death and facilitates Phytophthora infection. The direct targeting of ER stress regulators may represent a common mechanism of host manipulation by microbes.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Nature Publishing Group. The published article can be found at: http://www.nature.com/ncomms/index.htm

Focus on effector-triggered susceptibility

Effector biology exhibits diversity at every level. Effector proteins play key roles in the molecular interplay between plants and plant-associated organisms, and effector biology remains one of the most active areas in the research field of molecular plant-microbe interactions. Using effectors as probes, much has been learned about pathogen virulence and host immunity, which has broad implications in developing disease-resistant crops that are essential for global food security. Thus, the MPMI Editorial Board is publishing this Focus Issue to showcase recent progress in this area. Additional content is available on the Focus on Effector-Triggered Susceptibility. A Phytophthora palmivora Extracellular Cystatin-Like Protease Inhibitor Targets Papain to Contribute to Virulence on Papaya Conserved RxLR Effectors From Oomycetes Hyaloperonospora arabidopsidis and Phytophthora sojae Suppress PAMP- and Effector-Triggered Immunity in Diverse Plants Molecular Basis of Citrus sunki Susceptibility and Poncirus trifoliata Resistance Upon Phytophthora parasitica Attack daTALbase: A Database for Genomic and Transcriptomic Data Related to TAL Effectors Phytophthora parasitica Effector PpRxLR2 Suppresses Nicotiana benthamiana Immunity The Agrobacterium F-Box Protein Effector VirF Destabilizes the Arabidopsis GLABROUS1 Enhancer/Binding Protein-Like Transcription Factor VFP4, a Transcriptional Activator of Defense Response Genes Accessories Make the Outfit: Accessory Chromosomes and Other Dispensable DNA Regions in Plant-Pathogenic Fungi </jats:p