Sorrentino, Roberto (2014) caratterizzazione biologica, sierologica e molecolare di un nuovo Nepovirus riscontrato in Campania su Aeonium sp. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Resource language: Italiano
Title: caratterizzazione biologica, sierologica e molecolare di un nuovo Nepovirus riscontrato in Campania su Aeonium sp.
Date: 31 March 2014
Number of Pages: 123
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Agrobiologia e agrochimica
Ciclo di dottorato: 26
Coordinatore del Corso di dottorato:
Alioto, DanielaUNSPECIFIED
Date: 31 March 2014
Number of Pages: 123
Keywords: nepovirus, diagnosi, silenziamento
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/12 - Patologia vegetale
Date Deposited: 08 Apr 2014 09:25
Last Modified: 15 Jul 2015 01:02

Collection description

During 2011, Aeonium plants of an unidentified species with virus-like symptoms were collected from a private garden in Scafati (Salerno). Plants exhibited faint chlorotic spots and rings on both leaf surfaces. A virus was successfully transmitted, by sap inoculation, to test plants, including Nicotiana benthamiana which was used for electron microscopy observations and virus purification. Examination of tissue sap from symptomatic test and Aeonium plants revealed the presence of isometric particles with angular contours, ca. 30 nm in diameter. The particles presented single coat protein (CP) subunits 54 kDa in size, that encapsidated single-stranded positive-sense RNA species of 7,549 (RNA1) and 4,010 (RNA2) nucleotides. A third RNA molecule 3,472 nts in size, was detected in infected Aeonium plants: it is supposed to represent a defective interfering (DI) RNA because entirely derived from RNA2 with a 537 nts deletion in the coding region of movement protein. The structural genomic organization of both RNAs and the morphological and cytopathological features were comparable to those of nepoviruses. In addition, amino acid sequence comparisons of CP and the Pro-Pol region (a sequence containing parts of the proteinase and polymerase) with those of other nepoviruses showed that the Aeonium virus belongs to the subgroup A of the genus Nepovirus and is phylogenetically close to Tobacco ringspot virus (TRSV). Comparison of each single domain of TRSV and the Aeonium virus polyproteins disclosed a relatively low percentage of identity throughout. Moreover, the Aeonium virus showed to be serologically distinct from TRSV. Based on the species demarcation criteria for the family Secoviridae, the virus appears to be a novel member of the genus Nepovirus for which the name of Aeonium ringspot virus (AeRSV) is proposed. The evidence of recovery in test plants infected with AeRSV indicated the activation of post-transcriptional gene silencing. Thus, the second part of the study was focalized on the interaction of AeRSV with host defense responses during symptom induction and subsequent recovery. Results showed that, although RNA silencing is active during the recovery phase, the reduction of virus titer is not required for symptom disappearance. In addition, it was demonstrated that AeRSV does not code a suppressor for RNA silencing since it is unable to restore the wild phenotype in Arabidopsis reporter line SUC-SUL already silenced for the sulfur gene.


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