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Identifier 000391109
Title Λειτουργική ανάλυση των πρωτεϊνών p22 του Tomato chlorosis virus και p25 του Cucurbit yellow stunting disorder virus σε σχέση με την RNA σίγηση
Alternative Title Functional analysis of proteins p22 from ToCV and p25 from CYSDV in relation to Rna silencing
Author Σαπλαούρα, Ελευθερία Κ.
Thesis advisor Καλαντίδης, Κρίτων
Reviewer Τσαγρή, Ευθυμία
Βόντος, Ιωάννης
Abstract RNA silencing is the sequence-specific suppression of gene expression through the involvement of RNA. Plants use RNA silencing mostly for three purposes: 1) establishment and maintenance of heterochromatin state, 2) regulation of several endogenous functions and 3) antiviral defense. The trigger of antiviral RNA silencing is a double-stranded RNA that can occur during viral replication or in dsRNA structures into the viral genome. The dsRNAs are then processed into short interfering RNAs (siRNAs) and lead the post-transcriptional gene silencing (PTGS) of the viral RNA. Viruses encode for proteins that suppress RNA silencing, enabling the infection and its spread. Viral suppressors can target either the RNA molecules or the proteins and the complexes participating in the silencing pathway. Cucurbit yellow stunting disorder virus and Tomato chlorosis virus both encode for RNA silencing suppressors: p25 and p22 respectively. Through agroinfiltration assays in Wt and 16C (stable expression of GFP) Nicotiana benthamiana plants and subsequent Northern blot analysis, the effect of the suppressors on the RNA levels could be studied. Moreover, pull down assays were performed in order to detect any protein-protein interaction between the suppressors and silencing components. Finally, subcellular localization of p25 and p22 was studied using GFP tag and transgenic plants overexpressing the suppressors were generated to be used for future analyses. The results confirm preliminary studies and provide new insights on the way p25 and p22 might function. Specifically, both proteins suppress sense and hairpin PTGS and do not interfere with the movement of the silencing signal. ToCV p22 seems to locate mainly in the nucleus and decrease significantly the levels of all siRNAs, having a stronger effect on the 24-nt siRNAs. This may indicate a correlation with the function of DCL3. CYSDV p25 is found in the cytoplasm and is proposed to act downstream of siRNA generation. There is still more to be done in this project and the studies continue to discover the function of these suppressors.
Language Greek
Subject Crinivirus
Issue date 2015-03-20
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
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