Biological control of apple scab and fire blight by the application of the non-pathogenic bacterium Pseudomonas fluorescens Bk3 to the leaf surface

The biological control of plant diseases by application of antagonistic microorganisms to the plant phyllosphere is an alternative strategy to prevent the frequent treatment of plants by pesticides. Microbiological antagonists can firstly interact directly against the pathogen by releasing antimicrobial compounds and/or secondly induce the plant resistance of the host plant by expression of pathogenesis-related proteins (PR proteins). The focus of our study is on the interaction of the non-pathogenic bacterium Pseudomonas fluorescens Bk3 to the plant phyllosphere of Malus domestica cv. Holsteiner Cox. After application of P. fluorescens Bk3 to the phyllosphere of M. domestica cv. Holsteiner Cox we observed dramatic changes in the protein composition of the apoplast of the host plant. Sequencing of the induced proteins by ESI-Q-ToF mass spectrometry and homology search identified these additional proteins as pathogenesis related proteins (PR) like ß-1,3- glucanase, thaumatin-like protein, chitinase and hevein-like protein. To confirm these findings, a suppressive subtractive hybridization with total RNA from leaves before and after inoculation of P. fluorescens Bk3 to the leaves of the host plant was performed. It revealed an increased expression level of many PR and stress related genes. The induction of PR proteins and plant defence genes in host plants after application of non-pathogenic bacterial antagonists to the plant phylloshere can presumably prevent or reduce successful infections by plant pathogens

Up-regulation of pathogenesis-related proteins in the apoplast of Malus domestica after application of a non-pathogenic bacterium

The intercellular washing fluid (IWF) of Malus domestica cv. Holsteiner Cox before and after application of the non-pathogenic bacterium Pseudomonas fluorescens Bk3 to the leaves was investigated in a comparative manner. SDS-PAGE in combination with ESI Q-ToF mass spectrometry, and homology search in relevant data bases revealed the highly up-regulated expression of several pathogenesis-related plant proteins in the apoplast of the leaves treated with P. fluorescens. These proteins were β-1,3-glucanase, chitinase, thaumatin-like protein, ribonuclease-like protein, and a hevein-like protein. Moreover, a 9 kDa non-specific lipid transfer protein was significantly reduced after the application of P. fluorescens. The possible relevance of a pre-treatment of apple cultivars with the non-pathogenic bacterium P. fluorescens Bk3, as an alternative method to the treatment with fungicides, for increasing the resistance of susceptible apple cultivars against an infection with the fungus Venturia inaequalis is discussed

Energetic and Control Trade-offs in Spring-Wing Systems

Flying insects are thought to achieve energy-efficient flapping flight by storing and releasing elastic energy in their muscles, tendons, and thorax. However, flight systems consisting elastic elements coupled to nonlinear, unsteady aerodynamic forces also present possible challenges to generating steady and responsive wing motions. In previous work, we examined the resonance properties of a dynamically-scaled robophysical system consisting of a rigid wing actuated by a motor in series with a spring, which we call a spring-wing system \cite{Lynch2021-ri}. In this paper, we seek to better understand the effects of perturbations on resonant systems via a non-dimensional parameter, the Weis-Fogh number. We drive a spring-wing system at a fixed resonant frequency and study the response to an internal control perturbation and an external aerodynamic perturbation with varying Weis-Fogh number. In our first experiments, we provide a step change in the input forcing amplitude and study the wing motion response. In our second experiments we provide an external fluid flow directed at the flapping wing and study the perturbed steady-state wing motion. We evaluate results across the Weis-Fogh number, which describes the ratio of inertial and aerodynamic forces and the potential energetic benefits of elastic resonance. The results suggest that spring-wing systems designed for maximum energetic efficiency also experience trade-offs in agility and stability as the Weis-Fogh number increases. Our results demonstrate that energetic efficiency and wing maneuverability are in conflict in resonant spring-wing systems suggesting that mechanical resonance presents tradeoffs in insect flight

Phase diagram for morphological transitions of wetting films on chemically structured substrates

Using an interface displacement model we calculate the shapes of thin liquidlike films adsorbed on flat substrates containing a chemical stripe. We determine the entire phase diagram of morphological phase transitions in these films as function of temperature, undersaturation, and stripe widthComment: 15 pages, RevTeX, 7 Figure

Limits on the Dipole Moments of the τ\tau-Lepton via the Process $e^{+}e^{-}\to \tau^+ \tau^- \gamma in a Left-Right Symmetric Model

Limits on the anomalous magnetic moment and the electric dipole moment of the $\tau$ lepton are calculated through the reaction $e^{+}e^{-}\to \tau^+ \tau^- \gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\phi$, the effect of this angle on the dipole moments is quite small.Comment: 15 pages, 3 figure

Geometry dominated fluid adsorption on sculptured substrates

Experimental methods allow the shape and chemical composition of solid surfaces to be controlled at a mesoscopic level. Exposing such structured substrates to a gas close to coexistence with its liquid can produce quite distinct adsorption characteristics compared to that occuring for planar systems, which may well play an important role in developing technologies such as super-repellent surfaces or micro-fluidics. Recent studies have concentrated on adsorption of liquids at rough and heterogeneous substrates and the characterisation of nanoscopic liquid films. However, the fundamental effect of geometry has hardly been addressed. Here we show that varying the shape of the substrate can exert a profound influence on the adsorption isotherms allowing us to smoothly connect wetting and capillary condensation through a number of novel and distinct examples of fluid interfacial phenomena. This opens the possibility of tailoring the adsorption properties of solid substrates by sculpturing their surface shape.Comment: 6 pages, 4 figure

Templeting of Thin Films Induced by Dewetting on Patterned Surfaces

The instability, dynamics and morphological transitions of patterns in thin liquid films on periodic striped surfaces (consisting of alternating less and more wettable stripes) are investigated based on 3-D nonlinear simulations that account for the inter-site hydrodynamic and surface-energetic interactions. The film breakup is suppressed on some potentially destabilizing nonwettable sites when their spacing is below a characteristic lengthscale of the instability, the upper bound for which is close to the spinodal lengthscale. The thin film pattern replicates the substrate surface energy pattern closely only when, (a) the periodicity of substrate pattern matches closely with the characteristic lengthscale, and (b) the stripe-width is within a range bounded by a lower critical length, below which no heterogeneous rupture occurs, and an upper transition length above which complex morphological features bearing little resemblance to the substrate pattern are formed.Comment: 5 pages TeX (REVTeX 4), other comments: submitted to Phys. Rev.Let