رسائل دكتوراة
French
2015
Etude des pouvoirs antimicrobiens et pharmacologiques des extraits de Thymus vulgaris L. et l’induction de la défense chez la tomate vis-à-vis de Fusarium oxysporum, Botrytis cinerea, et Phytophtora parasitica.
Fouzia Benourad, Mokhtar Youcef-Benkada
كلية علوم الطبيعة والحياة-جامعة عبد الحميد بن باديس مستغانم · الجزائر
The present work aims to study the effectiveness of Thymus vulgaris extract; a native medicinaland aromatic plant to the fight diseases of plants and inducing natural defense powers. The invitro studied by direct contact with isolates showed total inhibition of mycelial growth andsporulation. In vivo, preventive treatment on seed and seedlings of tomato are made byapplying thyme extracts an few isolates responsible for foliar and soil-borne fungal disease, theresults show a very significant antifungal potency, no disease observed in studied pathtestsFOL/Solanum lycopercisi and Botrytis cenirea/Solanum lycopercisi. The elicitor power of thehydroalcoholic extract is explored through the analysis of gene expression by qRT-PCR, theprotein extracts and phenolic profile of tomato plants treated. The results of these experimentsshow clearly, induction of expression of the gene encoding the protein PR1P6 for more than200 times and the gene encoding chitinase4 for more than 50 again. However, the synthesis ofPR- proteins, no difference is observed on SDS-PAGE comparing with the control. However,the induction of the synthesis of PR1P6 protein is accomplished, is what was revealed byWestern blot. In parallel, the HPLC-DAD analysis shows that this is the thyme of thymolchemotype, and its extract is rich an free and glycosylated flavonoids. Moreover, the resultreveals the presence of salicylic acid known in the SAR signal and as an inducer of defensegenes. Based on these results, we can confirm the effectiveness of extracts of thyme as abiopesticide with botanical origin, wealth of natural extracts with bioactive molecules and thepresence of AS among the constituents of extracts of thyme entrusted the significant efficiencyby direct contact and in the induction of plant defense.On the other hand, prospective evaluation of the potential toxicity of repeated doses of extractsof thyme, is studied in Wistar rats by means of clinical chemistry, histopathology and via ametabonomics approach based on 1H-NMR spectrometry. Histopathologically, no sign ofabnormality or degeneration was observed in treated rats. As against the metabonomicsanalysis showed alterations of some metabolites involved in the energy metabolism of themitochondria of hepatocytes. However, the magnitude of adverse effects generated afterinjection of repeated doses of the essential oil of thyme is much lower compared to treatmentsapplied by the polyphenolic extract.