Biology and ecology of biofilms formed by a plant pathogen Phytophthora parasitica: From biochemical ecology to ecological engineering

AbstractIn nature, the organisation of microbial species into biofilms has a great influence on local environments and in human or plant diseases. This important trait of prokaryotes and eukaryotes is poorly understood while the knowledge of the related biological processes could constitute a novel base for controlling diseases. A study is developed on the oomycete Phytophthora parasitica belonging to a major class of eukaryotic plant pathogens to understand molecular and ecological basis of biofilm formation. The identification of signalling molecules and the definition of their spectrum of activity within the biofilm community will improve our understanding of fundamental biological processes, our ability to forecast pathogen behaviour and to elaborate new tools dedicated to plant diseases management with low environmental impact

Parental transfer of the antimicrobial protein LBP/BPI protects Biomphalaria glabrata eggs against oomycete infections

Copyright: © 2013 Baron et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was funded by ANR (ANR-07-BLAN-0214 and ANR-12-EMMA-00O7-01), CNRS and INRA. PvW was financially supported by the BBSRC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Quantification of salicylic acid (SA) and SA-glucosides in Arabidopsis thaliana

Homeostasis between the cytoplasmic plant hormone salicylic acid (SA) and its’ inactive, vacuolar storage forms, SA-2-O-β-D-glucoside (SAG) and SA-β-D-Glucose Ester (SGE), regulates the fine-tuning of defense responses to biotrophic pathogens in Arabidopsis thaliana. This protocol describes a simplified, optimized procedure to extract and quantify free SA and total hydrolyzable SA in plant tissues using a classical HPLC-based method

Solution structure of a tobacco lipid transfer protein exhibiting new biophysical and biological features

International audiencePlant lipid transfer proteins are small soluble extracellular proteins that are able to bind and transfer a variety of lipids in vitro. Recently, it has been proposed that lipid transfer proteins may play a key role in plant defence mechanisms, especially during the induction of systemic acquired resistance. However, very little is known about the proteins expressed in developing plants and tissues, since almost all the biophysical and structural data available to date on lipid transfer proteins originate from proteins present in storage tissues of monocot cereal seeds. In this paper, we report the structural and functional characteristics of a lipid transfer protein (named LTP1_1) constitutively expressed in young aerial organs of Nicotiana tabacum (common tobacco). The unlabelled and uniformly labelled proteins were produced in the yeast Pichia pastoris, and we determined the three-dimensional (3D) structure of LTP1_1 using nuclear magnetic resonance (NMR) spectroscopy and molecular modeling techniques. The global fold of LTP1_1 is very close to the previously published structures of LTP1 extracted from cereal seeds, including an internal cavity. However, the chemical shift variations of several NMR signals upon lipid binding show that tobacco LTP1_1 is able to bind only one LysoMyristoylPhosphatidylCholine (LMPC), while wheat and maize LTPs can bind either one or two. Titration experiments using intrinsic tyrosine fluorescence confirm this result not only with LMPC but also with two fatty acids. These differences can be explained by the presence in tobacco LTP1_1 of a hydrophobic cluster closing the second possible access to the protein cavity. This result suggests that LTP1 lipid binding properties could be modulated by subtle changes in a conserved global structure. The biological significance of this finding is discussed in the light of the signalling properties of the tobacco LTP1_1-jasmonate complex described elsewhere

Deciphering tomato defense after induction of resistance towards a biotrophic,a hemibiotrophic and a necrotrophic pathogen

National audienceIn this paper we describe our strategy to unravel the connection between plant defenses and plant resistance to pests. With tomato (Solanum lycopersicum) as the reference plant, our ambition is to screen different plant defense stimulators (SPD) and measure (i) the resulting protection leve! towards Phytophthora parasitica, Botrytis cinerea and Oïdium neolycopersici (ii) the genes involved in the corresponding defense mechanisms (iii) the proteins and secondary metabolites which could be effector of resistance. We already show that BABA induces a strong resistance to P. parasitica (100% protection, no symptoms). Conversely, SA does not protect tomato to P. parasitica infection even though some classical defense genes are highly up-regulated in the same manner after BABA and SA treatments. Preliminary results of RNA-Seq evidence that the expression of more than 1000 genes is modified by BABA treatment. The possible involvement of unreported functions is discussed

Deciphering tomato defense after induction of resistance towards a biotrophic,a hemibiotrophic and a necrotrophic pathogen

Poster présenté au 7. Meeting of IOBC-WPRS working group "Induced resistance in plants against insects and diseases": leaping from success in the lab to success in the field, Avignon, FRA (2013/06/10-13)International audienceIn this paper we describe our strategy to unravel the connection between plant defenses and plant resistance to pests. With tomato (Solanum lycopersicum) as the reference plant, our ambition is to screen different plant defense stimulators (SPD) and measure (i) the resulting protection leve! towards Phytophthora parasitica, Botrytis cinerea and Oïdium neolycopersici (ii) the genes involved in the corresponding defense mechanisms (iii) the proteins and secondary metabolites which could be effector of resistance. We already show that BABA induces a strong resistance to P. parasitica (100% protection, no symptoms). Conversely, SA does not protect tomato to P. parasitica infection even though some classical defense genes are highly up-regulated in the same manner after BABA and SA treatments. Preliminary results of RNA-Seq evidence that the expression of more than 1000 genes is modified by BABA treatment. The possible involvement of unreported functions is discussed

Biology and ecology of biofilms formed by a plant pathogen <em>Phytophthora parasitica</em>: from biochemical ecology to ecological engineering

National audienceIn nature, the organisation of microbial species into biofilms has a great influence on local environments and in human or plant diseases. This important trait of prokaryotes and eukaryotes is poorly understood while the knowledge of the related biological processes could constitute a novel base for controlling diseases. A study is developed on the oomycete Phytophthora parasitica belonging to a major class of eukaryotic plant pathogens to understand molecular and ecological basis of biofilm formation. The identification of signalling molecules and the definition of their spectrum of activity within the biofilm community will improve our understanding of fundamental biological processes, our ability to forecast pathogen behaviour and to elaborate new tools dedicated to plant diseases management with low environmental impact

BgLBP/BPI1s permeabilize membranes and induce death of short LPS <i>E. coli</i>.

<p>(A) Representative flow cytometry profiles of <i>E. coli SBS363</i> cells exposed to BSA (negative control), hBPI (positive control), native (n) BgLBP/BPI1 and recombinant (r) BgLBP/BPI1 at a concentration of 100 µg/ml, for 1 h. Cells have been stained with the Baclight kit (SYTO 9 and PI) and a total of 60,000 events were recorded for each sample. (B) Quantification of the effect of the four proteins on <i>E. coli SBS363</i> cell death (as measured in (A)). Cell death has been measured by flow cytometry after 1 hour exposure to 10 or 100 µg/ml proteins. Results are the mean percentages of permeabilized cells ± SE of three independent experiments. Asterisks indicate significant differences with negative control (*p<0.05, ***p<0.001).</p

BgLBP/BPI1s and hBPI display anti-oomycete activity against <i>P. parasitica</i> zoospores.

<p>Survival rate of <i>P. parasitica</i> zoospores after exposure to BSA, hBPI, rBgLBP/BPI1 and nBgLBP/BPI1. Zoospores were incubated with proteins at 5 (dark blue), 10 (red), 30 (green) and 100 µg/ml (purple). Negative controls (light blue) are zoospores without treatment. Results are mean percentages (± SE) of three independent experiments.</p

BgLBP/BPI1 is essential to protect eggs from oomycete infection.

<p>Typical egg mass from Luc- (A) or BgLBP/BPI1 (B) dsRNA-injected parents, after exposure to <i>S. diclina</i> zoospores. Note the well-developed mycelium (my). Egg masses from (A) and (B) have been laid 19–21 days after dsRNA injection to parents and have been exposed to zoospores at day 22. Observation was made after 8 days exposure to <i>S. diclina</i> zoospores.</p