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Identifier 000447093
Title Μελέτη υπερμολύνσεων ιοειδών, ιών & υποϊικών φυτοπαθογόνων.
Alternative Title Superinfections of viroids, viruses and subviral phytopathogens
Author Πενθερουδάκη, Ζωή Μ.
Thesis advisor Καλαντίδης, Κρίτων
Reviewer Τσαγρή, Ευθυμία
Χατζηβασιλείου, Ελισάβετ
Abstract Multiple pathogens infections occur more frequently in nature. Interactions between them can be competitive, neutral or cooperative and can have a significant impact on the epidemiology, the dynamics of disease and the evolution of their virulence. Infections usually result from sequential exposure of hosts to different pathogens. As viruses and viroids are some of the most important emerging threats to agricultural production, in planta quantification of the accumulation of each pathogen in their combined infections is necessary to assess the effect that one pathogen may have upon the other. Although many studies of plant-viruses’ interactions in host plant coinfections are reported, mixed viral-viroid infections have received comparatively less attention. Not until 1987, when Singh and Somerville reported natural co-infection of potato seedlings with both a virus and viroid at the same time, had such interactions been described. The purpose of this study was to investigate the interactions of viruses and viroids under approximation of natural conditions. As sequential infections in natural plant habitats are more likely than concomitant ones, two conditions were evaluated, Nicotiana benthamiana seedlings were first inoculated with a virus and after 7 days with a viroid, or alternatively, firstly inoculated with a viroid and then after 10 days with a virus. Specifically, the relationships of three singlestranded RNA viruses from different families (Bromoviridae and Tombusviridae) were evaluated separately, in superinfections with three viroids all belonging to the same family (Pospiviroidae) but not to the same genus. Analysis was done by Northern blotting, followed by quantitative and statistical analysis of the data. In addition, the effect of satellite RNAs (satRNAs) during coinfection of the helper virus with each viroid was investigated, as well as an attempt to characterize the interaction of a P19 protein virus mutant i.e., lacking the viral suppressor of RNA silencing (VSR) function. Lastly, the effect of temperature was examined on mixed viral-viroid infections. Mixed infections of that kind of pathogens approach the objective condition in their natural habitats and their study, with as many approaches as possible, is necessary to characterize their interaction. Peculiar results were obtained in the experiments performed, with varying levels of RNAs detected for each species of virus in combination with different species of viroid, even though the viroids studied belonged to the same genus. The overall results showed an increase mainly for viroids in mixed infections with viruses. Interestingly a decrease in both the viral and viroid titer, specific in the presence of satRNA, was described. The fluctuation of the viroid titer under different conditions of temperature stress was also of great interest. Interactions between these microscopic pathogens can be detrimental to agricultural production and possibly threaten human and animal food security in the future.
Language Greek
Subject CEVD
CMV
HSVD
PSTVD
SATL
TBSV
Issue date 2022-07-29
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/0/b/1/metadata-dlib-1648048638-285185-23823.tkl Bookmark and Share
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