Faculté Universitaire des Sciences agronomiques de Gembloux
diplôme d'études approfondies en sciences agronomiques et ingénierie biologique
du Jardin, Patrick
[fr] viroïde ; pêcher ; PLMVd
[en] Since several years, the Plant Pathology Unit studies the Peach latent mosaic viroid (PLMVd) and other viroids from fruit trees. These studies have led, first, to the lightening of new pseudoknot interactions potentially involved in the pathogenic mecanisms of the PLMVd. Secondly the existence of recombination events during the replication of the viroids was expressed. The first goal of this work was to create a collection of dimeric variants to be able to verify these hypothesys during the following years. Dimeric constructions of severe and latent variants were successfully obtained. Unfortunately, the variants selected to perform the recombination analysis contained too much mutations to be used. Finally two design of specific primers were performed. The first provides the possibility to create mutations in the pseudoknots and the second makes us able to detect recombinant variants. The second goal of this work was to set up the cDNA-AFLP on peach extracts to perform the caracterization of host-pathogen interactions between peach trees and the PLMVd.This will be made with collaboration of the Biochemistry and Catalityc RNA Departement of the Universtiy of Sherbrooke wich will analyze the miRNA pattern of infected and healthy plants. Based on former pathogenicity studies of differents variants performed in our Departement, the comparison of differentially expressed genes will include symptomatic and non symptomatic plants and also an healthy plant. Total RNA extracts were successfully performed and a first AFLP profile was obtained. However some steps of the manipulation need an optimization to produce reliable results.