Imbalanced Lignin Biosynthesis Promotes the Sexual Reproduction of Homothallic Oomycete Pathogens

Lignin is incorporated into plant cell walls to maintain plant architecture and to ensure long-distance water transport. Lignin composition affects the industrial value of plant material for forage, wood and paper production, and biofuel technologies. Industrial demands have resulted in an increase in the use of genetic engineering to modify lignified plant cell wall composition. However, the interaction of the resulting plants with the environment must be analyzed carefully to ensure that there are no undesirable side effects of lignin modification. We show here that Arabidopsis thaliana mutants with impaired 5-hydroxyguaiacyl O-methyltransferase (known as caffeate O-methyltransferase; COMT) function were more susceptible to various bacterial and fungal pathogens. Unexpectedly, asexual sporulation of the downy mildew pathogen, Hyaloperonospora arabidopsidis, was impaired on these mutants. Enhanced resistance to downy mildew was not correlated with increased plant defense responses in comt1 mutants but coincided with a higher frequency of oomycete sexual reproduction within mutant tissues. Comt1 mutants but not wild-type Arabidopsis accumulated soluble 2-O-5-hydroxyferuloyl-l-malate. The compound weakened mycelium vigor and promoted sexual oomycete reproduction when applied to a homothallic oomycete in vitro. These findings suggested that the accumulation of 2-O-5-hydroxyferuloyl-l-malate accounted for the observed comt1 mutant phenotypes during the interaction with H. arabidopsidis. Taken together, our study shows that an artificial downregulation of COMT can drastically alter the interaction of a plant with the biotic environment

Simulation moléculaire et calculs thermodynamiques

Communication oral

Molecular simulations of grafted metal-chelating monolayers: methodology, structure and energy

International audienceWe report molecular dynamics simulations of monolayers of copper complexes covalently attached to a graphite surface in water. Simulations are performed to calculate the structural (density profiles, distribution functions), dynamical (diffusion coefficients) and energetical properties of typical systems presenting a finite length in the third dimension. The results are discussed as a function of the method used for computing the long-range Coulombic interactions. Three different methodologies are used: a two dimensional method (HKE) more extensively in simulation time, the standard Ewald summation technique (EW3D) and the corrected Ewald method (EW3DC). From a computational viewpoint, the comparison between methods is essential to establish the set-up conditions and it represents a pre-requisite work before further investigating these grafted systems. We complete this study by providing a molecular description (structure, energy, diffusion, hydration) of the grafted monolayers of copper complexes and of the water molecules

Histoire et voyage de la Terre-Sainte, Où tout ce qu'il y a de plus remarquable dans les Saints lieux, est tres-exactement descrit. Par le R.P. Iaqves Goujon, Religieux de l' Obseruance de S. François Lecteur Iubilé de la Famille de Terre Sainte. Ouurage

Preface: , Goujon, JDedication: François Maria Rhini-A-PolitioContent description: IndexIllustration: 10 (Maps ,Views ,)Pagination: PP12+358P+9PPVolumes: 1Edition:1stText Genre:ProseIllustration: 10 (χάρτες ,τοπία ,

Le discours du voyage d' Oultremer au très victorieux Roi charls VII, prononcé, en 1452 par Jean Germain, êvèque de Chalon

Preface.Dedication:Illustration: (varia ,)Pagination: 1-40PVolumes: 1Text Genre:ProseIllustration: (άλλα θέματα ,

Dissipative particle dynamics simulations in the grand canonical ensemble: Applications to polymer brushes

International audienc

Compression of entangled polymer brushes using dissipative particle dynamics

Communication oraleInternational audienc

Mesoscopic simulation of entanglements using dissipative particle dynamics: application to polymer brushes

International audienc

Associated molecular liquids at the graphene monolayer interface

International audienceWe report molecular simulations of the interaction between a graphene sheet and different liquids such as water, ethanol and ethylene glycol. We describe the structural arrangements at the graphene interface in terms of density profiles, number of hydrogen bonds (HBs) and local structuration in neighboring layers close to the surface. We establish the formation of a two-dimensional HB network in the layer closest to the graphene. We also calculate the interfacial tension of liquids with a graphene monolayer and its profile along the direction normal to the graphene to rationalize and quantify the strengthening of the intermolecular interactions in the liquid due to the presence of the surface

The compression of polymer brushes under shear: the friction coefficient as a function of compression, shear rate and the properties of the solvent

International audienc