Plant-RNA viroid relationship: a complex host pathogen interaction

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3),

Viroids are non encapsidated small RNA plant pathogens unable to produce any protein. They are able to infect dramatically a broad range of plants including herbaceous and tree crops. The ways by which ... [more ▼]

Viroids are non encapsidated small RNA plant pathogens unable to produce any protein. They are able to infect dramatically a broad range of plants including herbaceous and tree crops. The ways by which viroids are able to induce diseases are actually unknown. However, recent studies have shown that viroids are able to regulate the gene expression of their hosts, they can modify the host-protein phosphorylation sensibility and they interact with host-protein implicated RNA trafficking and protein phosphorylation. Moreover during their evolution plants have developed a mechanism able to regulate their gene expression and to degrade exogenous RNAs like viroids: the gene silencing. Unfortunately, this pathway seems, now, also highly implicated in the symptoms development. This review describes studies that are realized since a few years to increase the knowledge about the plant-viroid relationship. [less ▲]

Le marche des agents de lutte biologique en Europe: situation actuelle et perspectives

Conference (2010)

présentation des travaux de recherche en lutte biologique

Conference (2009, June)

Pourquoi n'y a-t-il pas plus de biopesticides sur le marché?

Scientific conference (2009, January)

High salt-tolerant protease from a potential biocontrol agent bacillus pumilus M3-16

in Annals of Microbiology (2009), 59(3), 553-558

In this paper, we investigate the characterization and evaluation of the antifungal protease activity from a halotolerant strain M3-16 of Bacillus pumilus, earlier isolated from a shallow salt lake in ... [more ▼]

In this paper, we investigate the characterization and evaluation of the antifungal protease activity from a halotolerant strain M3-16 of Bacillus pumilus, earlier isolated from a shallow salt lake in Tunisia. Protease enzyme was highly induced by the pathogen tested in vitro (27.4 U/ml). This is the first report on high salt-tolerant protease from B. pumilus, since it was active at high salinity (from 5 to 30% NaCl, w/v) as well as in the absence of salinity. This enzyme showed optimal activity at 60 °C and pH 8. At 80 °C and 30 min, the enzyme retained up to 91% and it showed stability over a wide pH range (from pH 5 to 11). The enzyme was found to be monomer with an estimated molecular mass of 31 kDa. The amino acid sequence showed high similarity (94%) to ATP-dependent protease from B. pumilus strain ATCC 7061. Thus, our alkaline thermostable and high salt-tolerant protease induced by a phytopathogenic fungus, could be useful for application in diverse areas such as biotechnology alimentary and agronomy industries. [less ▲]

Biological control of grey mould in strawberry fruits by halophilic bacteria

in Journal of Applied Microbiology (2009), 106(3), 833-846

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from ... [more ▼]

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from hypersaline ecosystems and evaluate the abilities of antifungal bacteria to secrete extracellular hydrolytic enzymes, anti- Botrytis metabolites and volatiles. Methods and Results: Grey mould was reduced in strawberry fruits treated with halophilic antagonists and artificially inoculated with B. cinerea. Thirty strains (20Æ2%) were active against the pathogen and reduced the percentage of fruits infected after 3 days of storage at 20 C, from 50% to 91Æ66%. The antagonists were characterized by phenotypic tests and 16S rDNA sequencing. They were identified as belonging to one of the species: Virgibacillus marismortui, B. subtilis, B. pumilus, B. licheniformis, Terribacillus halophilus, Halomonas elongata, Planococcus rifietoensis, Staphylococcus equorum and Staphylococcus sp. The effective isolates were tested for antifungal secondary metabolites. Conclusions: Moderately halophilic bacteria may be useful in biological control against this pathogen during postharvest storage of strawberries. Significance and Impact of the study: The use of such bacteria may constitute an important alternative to synthetic fungicides. These moderate halophiles can be exploited in commercial production and application of the effective strains under storage and greenhouse conditions. [less ▲]

Enhancement of the biocontrol agent Candida Oleophila (strain O) survival and control efficiency under extreme conditions of water activity and relative humidity

in Biological Control (2009), 51(3), 403-408

Evaluation en in vitro de l'activite biofongicide des huiles essentielles contre 3 phytopathogenes

Conference (2009)

Combining an original method for preserving RNA expression in situ with an effetive RNA method makes it possible to study gene expression in any banana fruit tissue.

in Fruits (2009), 64(3), 127-137

Introduction. RNA isolation is a prerequisite to studying gene expression in banana and to understanding changes occurring in response to the environment. Standard extraction methods do not efficiently ... [more ▼]

Introduction. RNA isolation is a prerequisite to studying gene expression in banana and to understanding changes occurring in response to the environment. Standard extraction methods do not efficiently extract RNA from plants such as banana, with high levels of phenolics, carbohydrates, or other compounds that bind to and/or coprecipitate with RNA. Materials and methods. Five to seven RNA extraction methods were compared. Four crowntissue storage methods were also compared. cDNA-AFLP was used to ensure that the obtained RNA was of sufficient quality for molecular applications and that RNA expression was unaltered by in situ storage. Results and discussion. The modified hot-borate method proved to be the best RNA extraction method, allowing high yields of good quality, undegraded RNA from the crown, fruit peel and pulp at all stages of ripening. The RNA obtained by this method was of sufficient quality for molecular applications such as cDNA-AFLP that give highly reproducible results. Freeze-drying of fresh tissues and tissue conservation in hot-borate buffer, two original storage methods, appear appropriate for preserving RNA in situ without ultra-low temperature. The RNA obtained was of high quality, undegraded, and useful for all downstream applications. The genome expression profile obtained by cDNA-AFLP analysis was unaltered by these methods for storing collected tissues. Conclusion. By applying all the suggested procedures in this work, it is possible to store and study gene expression in any banana fruit tissue, whatever the maturity stage, without affecting the RNA expression level. [less ▲]

News insights on the molecular host-pathogen relationship between peach trees and peach latent mosaic ciroid.

Conference (2009)