Time filter

Source Type

Rezgui A.,Tunis el Manar University | Rezgui A.,French National Institute for Agricultural Research | Rezgui A.,University of Bordeaux 1 | Ben Ghnaya-Chakroun A.,Tunis el Manar University | And 8 more authors.
Biological Control | Year: 2016

Vineyards throughout the world, including Tunisia, are being attacked by Grapevine Trunk Diseases (GTDs) such as Esca and Botryosphaeriae dieback. In this study, the bacterial microflora colonizing the non-necrotic and necrotic wood tissues of Tunisian mature grapevines (cv Muscat d'Italie) was investigated. Both types of tissues were studied in order to decipher microbial communities associated with them and to find a suitable BCA that can be applied to the Tunisian terroir. Single-Strand Conformation Polymorphism (SSCP) analyses showed that complex bacterial communities specifically colonized both types of wood tissues. The 19 most abundant cultivable strains, selected on their morphology, were isolated from plant samples and assigned to Pantoea, Pseudomonas, Curtobacterium and Bacillus species based on the 16S rRNA and rpoB genes. Biochemical and microbiological screenings revealed that those 19 strains (i) metabolized differently carbon sources, even within the same species, (ii) possessed antibiotic genes, (iii) produced siderophores and solubilized phosphates and (iv) had an in vitro antagonistic effect against 3 fungal pathogens (Lasidiodiplodia pseudotheobromae, Neofusicoccum parvum and Schizophyllum commune) involved in GTDs. One strain, Bacillus subtilis "B6", had a positive effect on young vines of a cultivar, Muscat d'Italie, frequently planted in Tunisia, by reducing the size of the wood necrosis caused by N. parvum, showing its potential to counteract infection caused by this GTDs agent. © 2016 Elsevier Inc.

Rebib H.,Tunis el Manar University | Rebib H.,French National Institute for Agricultural Research | Bouraoui H.,Tunis el Manar University | Rouaissi M.,Laboratoire Of Biotechnologie Appliquee A Lagriculture | And 4 more authors.
European Journal of Plant Pathology | Year: 2014

Fusarium culmorum is a major pathogen able to cause foot and root rot and the incitant of Fusarium head blight in wheat in Tunisia. The aims of the present study were to evaluate by PCR the type of mycotoxins produced, to determine the mating type and to analyse the genetic diversity by microsatellite markers of 82 F. culmorum isolates recovered from two separated Tunisian fields. Specific sequences in the Tri6-Tri5 intergenic region, Tri7 and Tri13 were used to identify 3-AcDON- or 15-AcDON-. All studied F. culmorum isolates, were of the 3-AcDON- type. No 15-AcDON- and NIV types were detected in this research. Both mating types MAT1-1 and MAT1-2 were recovered from the two fields in approximately equal proportions. Five polymorphic microsatellite markers were applied to F. culmorum isolates, to determine the genetic variation in and among populations. Sixty-four haplotypes were identified; the analysis of the population structure did not reveal a strong variation between fields. Total gene diversity (H T = 0.505; H S = 0.497) and analysis of molecular variance confirmed that most of the genetic variability was within populations (Φ ST = 0.033; P<0.0039). Gene flow (N m = 31.05) indicated little differentiation among populations. Based on these results, the F. culmorum isolates collected from different fields might be part of one large panmictic population and in addition the low linkage disequilibrium values with high genetic variation within populations suggest that the population is recombining sexually. © 2014 Koninklijke Nederlandse Planteziektenkundige Vereniging.

Kalai-Grami L.,Laboratoire des Substances Bioactives | Kalai-Grami L.,Laboratoire Of Biotechnologie Appliquee A Lagriculture | Ben Slimane I.,Laboratoire des Substances Bioactives | Mnari-Hattab M.,Laboratoire Of Biotechnologie Appliquee A Lagriculture | And 4 more authors.
World Journal of Microbiology and Biotechnology | Year: 2014

Isolate TEB1 an antagonistic endophytic bacterium, obtained from citrus leaves and identified as Bacillus amyloliquefaciens by 16S rDNA sequencing, was used for the biological control of mal secco disease of Citrus aurantium seedlings caused by the mitosporic fungus Phoma tracheiphila. The isolate TEB1 exhibited a good in vitro activity against P. tracheiphila in dual cultures as well as with the well diffusion method. C. aurantium seedlings watered with a suspension of TEB1 cells showed a reduction of 53.61 and 48.63 % in disease severity and incidence, respectively. A PCR test with specific primers was performed 365 days after inoculation and P. tracheiphila was detected along the whole stem in inoculated control plant while no amplification product was obtained in TEB1 treated seedlings. Molecular analysis of TEB1 revealed a positive amplification of fenD and ituC genes responsible of the biosynthesis of fengycin and iturin lipopeptides, respectively. Moreover, observations by optical microscope showed that TEB1 reduced by 55 % the germination of P. tracheiphila conidia and exhibited a marked effect on mycelia structure. Data suggest that lipopeptides produced by the bacterium interact with the cytoplasmic membrane of the fungus causing pore formation. TEB1 appears a potential candidate for the biological control of citrus mal secco disease. © 2013 Springer Science+Business Media Dordrecht.

Loading Laboratoire Of Biotechnologie Appliquee A Lagriculture collaborators
Loading Laboratoire Of Biotechnologie Appliquee A Lagriculture collaborators