Deep sequencing analysis of an asymptomatic grapevine revealed a virome containing five RNA viruses and a viroid. Of these, Grapevine leafroll-associated virus 7 (GLRaV-7), an unassigned closterovirus, was by far the most prominently represented sequence in the analysis. Graft-inoculation of the infection to another grape variety confirmed the lack of the leafroll disease symptoms, even though ...

The chrysanthemum (Dendranthema X grandiflorum) belongs to the family Asteraceae and it is one of the most popular flowers in the world. Viroids are the smallest known plant pathogens. They consist of a circular, single-stranded RNA, which does not encode a protein. Chrysanthemums are a common host for two different viroids, the Chrysanthemum stunt viroid (CSVd) and the Chrysanthemum chlorotic ...

Viroids are small (about 300 nucleotides), single-stranded, circular, non-encapsidated pathogenic RNA molecules. They do not code for proteins and thus depend on plant host enzymes for their replication and other functions. They induce plant diseases by direct interaction with host factors but the mechanism of pathogenicity is still unknown. They can alter the expression of selected plant genes...

Virus-infected plants accumulate abundant, 21-24 nucleotide viral siRNAs which are generated by the evolutionary conserved RNA interference (RNAi) machinery that regulates gene expression and defends against invasive nucleic acids. Here we show that, similar to RNA viruses, the entire genome sequences of DNA viruses are densely covered with siRNAs in both sense and antisense orientations. This ...

Next generation sequencing (NGS) technologies are becoming routinely employed in different fields of virus research. Different sequencing platforms and sample preparation approaches, in the laboratories worldwide, contributed to a revolution in detection and discovery of plant viruses and viroids. In this work, we are presenting the comparison of two RNA sequence inputs (small RNAs vs. ribosoma...

Background and Aims: Viroids are smallest known plant pathogens and cause several economically significant diseases. Until recently, viroid detection relied mainly on biological tests and indexing. Today various diagnostic techniques such as nucleic acid hybridization, southern blot and reverse transcription coupled with polymerase chain reaction (RT-PCR) are being used for detection and diag...

Grapevine virus H (GVH) is a member of the genus Vitivirus in family Betaflexiviridae (subfamily Trivirinae, order Tymovirales) that infects grapevine (Candresse et al., 2018). GVH was first identified symptomless an unknown cultivar from Portugal 2018 al. 2018), and since then has been reported only California (Diaz‑Lara 2019). Several vitiviruses have detected Greek vineyards (Avgelis Roubos ...

Viroids are infectious agents identified only in plants so far. In contrast to viruses, the genome of viroids is composed of a tiny circular RNA (250-400 nt) not coding for proteins, but containing in its compact structure all the information needed for parasitizing the transcriptional and RNA trafficking machineries of their hosts. Viroid infections are frequently accompanied by cellular and d...

in this study, the possible infection of thomson navel, moro blood sweet orange, page mandarin and webber pomelo with citrus viroids was investigated. biological indexing was performed by grafting on etrog citron (c. medica) and maintained in temperature-controlled greenhouse. after inoculation, rna was extracted by sds– potassium acetate method. detection of citrus viroids was done reverse tra...

Viroids are autonomously replicating, small singlestranded circular RNA molecules that do not code for proteins and may cause disease in infected, susceptible plants. Viroids have the ability to induce both RNA-mediated transcriptional gene silencing (TGS) and posttranscriptional gene silencing (PTGS) in infected plants. Viroid PTGS has also been demonstrated in a wheat germ extract system. A p...