1,659 research outputs found
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
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 -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
lepton are calculated through the reaction at the -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 , 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
Wurtzite Effects on Spin Splitting of GaN/AlN Quantum Wells
A new mechanism (DeltaC1-DeltaC3 coupling) is accounted for the spin
splitting of wurtzite GaN, which is originated from the intrinsic wurtzite
effects (band folding and structure inversion asymmetry). The band-folding
effect generates two conduction bands (DeltaC1 and DeltaC3), in which p-wave
probability has tremendous change when kz approaches anti-crossing zone. The
spin-splitting energy induced by the DeltaC1-DeltaC3 coupling and wurtzite
structure inversion asymmetry is much larger than that evaluated by traditional
Rashba or Dresselhaus effects. When we apply the coupling to GaN/AlN quantum
wells, we find that the spin-splitting energy is sensitively controllable by an
electric field. Based on the mechanism, we proposed a p-wave-enhanced
spin-polarized field effect transistor, made of InxGa1-xN/InyAl1-yN, for
spintronics application.Comment: 12 pages, 4 figures (total 16 pages
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