Caractérisation moléculaire et par MALDI-TOF MS des espèces fongiques phytopathogènes inféodées aux céréales et mise en évidence de l’impact de l’utilisation des antifongiques azolés sur la résistance des souches.

Abstract

Winter cereals including wheat remain the staple food of the Algerian diet and show a strategic importance in both human and animal nutrition. Many fungal diseases may attack wheat farmings, These attacks may cause great loss when the used varieties are sensitive. The mildews are phytopathogenic But, they are eventually responsible of human pathologies. The treatment protects the plant from every external contamination. The best phytosanitary protection of wheat farmingsis assured via two types of treatments; fungicidal and insecticide. The fungicides if used to destroy pathogenic fungi which attach the farmings, seeds and harvested products. Currently, the mildews are becoming resistant in the environment, because of the exercised pressure through the use of fungicides. The most common mildew’s resistance mechanism is the mutation of the cyp51 gene coding 14alpha-Demethylase sterol. The azolated antifungals inhibit this enzyme, leading to blocking the biosynthesis of the ergosterol which leads to deplete the ergosterol And to an accumulation of toxic metabolites. In this context, we have conducted a comparative study both seed samples, leaves and wheat spikes: one of them is treated by the azolated fungicide of type: Raxil® 060 FS, l’Artea330EC and Amistar® Xtra while the other is kept untreated in order to evaluate the efficiency of triazoles and the degree of protection of the wheat farming after a fungicidal treatment in the province of Constantine (Algeria). According to the mycological analysis of the samples, 114 strains have been isolated; the species of Aspergillus and Penicillium genus are the most dominant. 6 species resistant against the treatments were selected for the study of fungicidal effects including (A. flavus, A. tubingensis, P. glabrum, P.griseofulvum, T. harzianium and A. alternate). The study of the sensitivity of these isolates covers firstly the evaluation of the in vitro activity of the pre-described fungicides via a diffusion technique. In addition, the obtained results validated with a statistical analysis revealed that the tested fungicides caused a decrease in the pycnidial Coating compared to control samples. Secondly, the detection of resistance mutations in the isolate’s cyp51 gene was accomplished through the analysis of this latter. The obtained results were treated using a bioinformatics approach in order to exploit them.