Effects of leaf surface and temperature on monocyclic processes in Podosphaera aphanis, causing powdery mildew of strawberry

International audiencePowdery mildew of strawberry, caused by Podosphaera aphanis, is an important constraint to production in tunnels and greenhouses. A better knowledge of the effect of environment on the disease is needed to design efficient management methods. In diseases such as strawberry powdery mildew, the very notion of lesion is difficult to grasp, and progress in disease management has been slow because observations pertaining to the monocyclic processes are difficult and time consuming. Experiments under controlled conditions were conducted to measure the effects of leaf surface (abaxial or adaxial) and air temperature on the different monocyclic processes of the disease. The fraction of germinated spores on the lower (abaxial) leaf surface (0.51–0.84) was 10%-20% larger than on the upper (adaxial) leaf surface. Infection efficiency was 10 times lower on the upper than on the lower leaf surface. Temperature strongly influenced all monocyclic processes considered: spore germination, infection efficiency, latent period, colony size, and colony sporulation. The optimum temperature was 22 °C, and no infection occurred at 32 °C. Implications of the results on disease management are discussed.L’oïdium du fraisier, causé par Podosphaera aphanis, est une importante contrainte pour la production de fraisiers en serre et sous tunnel. Une meilleure connaissance des effets de l’environnement sur cette maladie est nécessaire pour élaborer des méthodes de gestion efficaces. Comme c’est le cas pour de nombreuses maladies telles que l’oïdium du fraisier, où la notion même de lésion est difficile à appréhender, les progrès pour la gestion de cette maladie ont été lents car les observations liées aux processus monocycliques sont difficiles et laborieuses. Des expérimentations en conditions contrôlées ont été conduites pour mesurer les effets de la température de l’air et de la surface de feuille (abaxiale ou adaxiale) sur les différents processus monocycliques de cette maladie. Le taux de germination sur face inférieure (abaxiale) de feuilles (0.51–0.84) était 10 % à 20 % plus grand que sur la face supérieure (adaxiale). L’efficacité d’infection était 10 fois plus faible sur la face supérieure que sur la face inférieure de feuille. La température influençait fortement tous les processus monocycliques considérés : germination des spores, efficacité d’infection, période de latence, taille des colonies, sporulation. La température optimale était de 22 °C, et aucune infection ne s’est développée à 32 °C. Les implications de ces résultats pour la gestion de cette maladie sont discutées

Spore dispersal and disease gradients in strawberry powdery mildew

International audienceSpore dispersal and disease gradients were measured in powdery mildew of strawberry (Fragaria × ananassa), caused by Podosphaera aphanis, under two production systems: a glasshouse and a plastic tunnel. All gradients could be well described by exponential and power law models, but the power law model provided a better description, particularly at large distances. Primary gradients were associated with spore dispersal occurring predominantly within 1.20 m. Slope estimates ranged between 0.025 and 0.075 cm−1 and between 0.8 and 1.7 for the exponential and power law models, respectively. Spore dispersal was considerably greater in the tunnel than in the glasshouse, where epidemics did not develop. Disease gradients in the tunnel became shallower as epidemics developed and were associated with decreasing slope estimates over time. The differences between tunnel and glasshouse were assumed to reflect differences in wind speed, which was about 10 times lower in the glasshouse than in the tunnel.Les gradients de dispersion de spores et de propagation de maladie ont été mesurés chez l’oïdium du fraisier (Fragaria × ananassa), causé par Podosphaera aphanis, dans deux systèmes de production : sous serre en verre et sous tunnel plastique. Tous les gradients ont pu être décrits de manière satisfaisante par les modèles exponentiels et puissance, mais le modèle puissance a permis une meilleure description des gradients notamment aux distances les plus grandes. Les gradients primaires étaient associés à une dispersion des spores effectuée principalement dans un rayon de 1,20 m. Les estimations de la pente du gradient variaient entre 0,025 et 0,075 cm−1 et entre 0,8 et 1,7, pour les modèles exponentiel et puissance, respectivement. La dispersion des spores était beaucoup plus importante en tunnel qu’en serre, où aucune épidémie ne s’est développée. Les gradients de propagation de maladie en tunnel devenaient plus plats, et étaient associés avec des paramètres de pente plus faibles, au fur et à mesure que les épidémies se développaient. Il est supposé que les différences entre tunnel et serre reflétaient les différences de vitesse de vent, celle-ci étant environ 10 fois plus faible en serre qu’en tunnel

Irreversible degradation of Nb3_3Sn Rutherford cables due to transverse compressive stress at room temperature

In the framework of the Future Circular Collider design study for a 100 TeV circular collider, 16 T superconducting bending magnets based on Nb$_3$Sn technology are being developed. A pre-stress on the conductor during magnet assembly at room temperature (RT) is needed to counteract the Lorentz forces during operation. The superconducting properties of the brittle Nb$_3$Sn superconductor are strain sensitive and excessive pre-stress leads to an irreversible degradation of the superconductor. In order to determine the level of acceptable pre-stress during the magnet assembly process, reacted and impregnated Nb$_3$Sn cables were exposed to increasing transverse compressive stress up to a maximum stress level of 200 MPa at RT. After each stress cycle, the critical current of the cable specimens were characterized at 4.3 K in the FRESCA cable test station. No significant critical current degradation was observed up to 150 MPa, followed by degradation less than 4% after a nominal stress of 175 MPa. A dramatic permanent critical current degradation occurred after applying a nominal stress of 200 MPa. A comprehensive post analysis consisting of non-destructive micro-tomography followed by microscopic characterization of metallographic cable cross sections was carried out after the critical current test to reveal cracks in the Nb$_3$Sn sub-elements of the loaded specimen

Design Optimization of the Nb3SnNb_3Sn 11 T Dipole for the High Luminosity LHC

Abstract: As a part of the large hadron collider luminosity upgrade (HiLumi-LHC) program, CERN is planning to replace some of the 8.33-T 15-m-long Nb-Ti LHC main dipoles with shorter 11 T Nb$_{3}$Sn magnets providing longitudinal space for additional collimators. Whereas the present design of the 11 T dipole enables the use of RRP conductor with critical current degradation after cabling at the level of 5%, new cross sections of the cable have been studied in order to further decrease the degradation of both critical current and resistivity of the copper matrix. This change is particularly beneficial for the PIT conductor. The coil layout is reoptimized to accommodate the new cable geometry, using the ROXIE code. A set of additional design changes are implemented, such as reduction of the outer yoke diameter. In this paper, we review the main parameters of the present design, describe the changes implemented in the new design, and discuss their impact on both the electromagnetic and structural properties

The crane fly glycosylated triketide delta-lactone cornicinine elicits akinete differentiation of the cyanobiont in aquatic Azolla fern symbioses

Güngör E, Savary J, Adema K, et al. The crane fly glycosylated triketide delta-lactone cornicinine elicits akinete differentiation of the cyanobiont in aquatic Azolla fern symbioses. Plant, Cell and Environment . 2024.The restriction of plant-symbiont dinitrogen fixation by an insect semiochemical had not been previously described. Here we report on a glycosylated triketide delta-lactone from Nephrotoma cornicina crane flies, cornicinine, that causes chlorosis in the floating-fern symbioses from the genus Azolla. Only the glycosylated trans-A form of chemically synthesized cornicinine was active: 500nM cornicinine in the growth medium turned all cyanobacterial filaments from Nostoc azollae inside the host leaf-cavities into akinetes typically secretingCTB-bacteriocins. Cornicinine further inhibited akinete germination in Azolla sporelings, precluding re-establishment of the symbiosis during sexual reproduction. It did not impact development of the plant Arabidopsis thaliana or several free-living cyanobacteria from the genera Anabaena or Nostoc but affected the fern host without cyanobiont. Fern-host mRNA sequencing from isolated leaf cavities confirmed high NH4-assimilation and proanthocyanidin biosynthesis in this trichome-rich tissue. After cornicinine treatment, it revealed activation of Cullin-RING ubiquitin-ligase-pathways, known to mediate metabolite signaling and plant elicitation consistent with the chlorosis phenotype, and increased JA-oxidase, sulfate transport and exosome formation. The work begins to uncover molecular mechanisms of cyanobiont differentiation in a seed-free plant symbiosis important for wetland ecology or circular crop-production today, that once caused massive CO2 draw-down during the Eocene geological past. © 2024 John Wiley & Sons Ltd

Comparison of Cold Powering Performance of 2-m-Long Nb3_{3}Sn 11 T Model Magnets

For the upgrade of the LHC, two 15-m NbTi main dipole magnets are foreseen to be replaced by two 11 T 5.7-m-long Nb$_{3}$Sn dipoles each. A series of model magnets has been produced to verify the design choices that are important for the prototype and series production, focusing on mechanical aspects and protection studies. A fourth and a fifth 2-m single aperture models were produced, assembled, and tested. In this paper, the cold powering tests of the single aperture models SP104 and SP105 will be presented and the results will be compared with the previous models. Special attention will be given to the upper limit in magnet current due to quenches in the midplane turns

Sensitivity Analyses of Exposure Estimates from a Quantitative Job-exposure Matrix (SYN-JEM) for Use in Community-based Studies

<p>Objectives: We describe the elaboration and sensitivity analyses of a quantitative job-exposure matrix (SYN-JEM) for respirable crystalline silica (RCS). The aim was to gain insight into the robustness of the SYN-JEM RCS estimates based on critical decisions taken in the elaboration process.</p><p>Methods: SYN-JEM for RCS exposure consists of three axes (job, region, and year) based on estimates derived from a previously developed statistical model. To elaborate SYN-JEM, several decisions were taken: i.e. the application of (i) a single time trend; (ii) region-specific adjustments in RCS exposure; and (iii) a prior job-specific exposure level (by the semi-quantitative DOM-JEM), with an override of 0 mg/m(3) for jobs a priori defined as non-exposed. Furthermore, we assumed that exposure levels reached a ceiling in 1960 and remained constant prior to this date. We applied SYN-JEM to the occupational histories of subjects from a large international pooled community-based case-control study. Cumulative exposure levels derived with SYN-JEM were compared with those from alternative models, described by Pearson correlation (R-p) and differences in unit of exposure (mg/m(3)-year). Alternative models concerned changes in application of job-and region-specific estimates and exposure ceiling, and omitting the a priori exposure ranking.</p><p>Results: Cumulative exposure levels for the study subjects ranged from 0.01 to 60 mg/m(3)-years, with a median of 1.76 mg/m(3)-years. Exposure levels derived from SYN-JEM and alternative models were overall highly correlated (R-p > 0.90), although somewhat lower when omitting the region estimate (R-p = 0.80) or not taking into account the assigned semi-quantitative exposure level (R-p = 0.65). Modification of the time trend (i.e. exposure ceiling at 1950 or 1970, or assuming a decline before 1960) caused the largest changes in absolute exposure levels (26-33% difference), but without changing the relative ranking (R-p = 0.99).</p><p>Conclusions: Exposure estimates derived from SYN-JEM appeared to be plausible compared with (historical) levels described in the literature. Decisions taken in the development of SYN-JEM did not critically change the cumulative exposure levels. The influence of region-specific estimates needs to be explored in future risk analyses.</p>

Integrated clinical and omics approach to rare diseases novel genes and oligogenic inheritance in holoprosencephaly

International audienceHoloprosencephaly is a pathology of forebrain development characterized by high phenotypic heterogeneity. The disease presents with various clinical manifestations at the cerebral or facial levels. Several genes have been implicated in holoprosencephaly but its genetic basis remains unclear different transmission patterns have been described including autosomal dominant, recessive and digenic inheritance. Conventional molecular testing approaches result in a very low diagnostic yield and most cases remain unsolved. In our study, we address the possibility that genetically unsolved cases of holoprosencephaly present an oligogenic origin and result from combined inherited mutations in several genes. Twenty-six unrelated families, for whom no genetic cause of holoprosencephaly could be identified in clinical settings [whole exome sequencing and comparative genomic hybridization (CGH)-array analyses], were reanalysed under the hypothesis of oligogenic inheritance. Standard variant analysis was improved with a gene prioritization strategy based on clinical ontologies and gene co-expression networks. Clinical phenotyping and exploration of cross-species similarities were further performed on a family-by-family basis. Statistical validation was performed on 248 ancestrally similar control trios provided by the Genome of the Netherlands project and on 574 ancestrally matched controls provided by the French Exome Project. Variants of clinical interest were identified in 180 genes significantly associated with key pathways of forebrain development including sonic hedgehog (SHH) and primary cilia. Oligogenic events were observed in 10 families and involved both known and novel holoprosencephaly genes including recurrently mutated FAT1, NDST1, COL2A1 and SCUBE2. The incidence of oligogenic combinations was significantly higher in holoprosencephaly patients compared to two control populations (P < 10-9). We also show that depending on the affected genes, patients present with particular clinical features. This study reports novel disease genes and supports oligogenicity as clinically relevant model in holoprosencephaly. It also highlights key roles of SHH signalling and primary cilia in forebrain development. We hypothesize that distinction between different clinical manifestations of holoprosencephaly lies in the degree of overall functional impact on SHH signalling. Finally, we underline that integrating clinical phenotyping in genetic studies is a powerful tool to specify the clinical relevance of certain mutations