The analysis of the first plant genomes provided unexpected evidence for genome duplication events in species that had previously been considered as true diploids on the basis of their genetics. These polyploidization events may have had important consequences in plant evolution, in particular for species radiation and adaptation and for the modulation of functional capacities. Here we report a...

The mutation rates of viroids, plant pathogens with minimal non-protein-coding RNA genomes, are unknown. Their replication is mediated by host RNA polymerases and, in some cases, by hammerhead ribozymes, small self-cleaving motifs embedded in the viroid. By using the principle that the population frequency of nonviable genotypes equals the mutation rate, we screened for changes that inactivated...

The complete cDNA of hop stunt viroid (HSV) has been cloned by the method of Okayama and Berg (Mol.Cell.Biol.2,161-170. (1982] and the complete nucleotide sequence has been established. The covalently closed circular single-stranded HSV RNA consists of 297 nucleotides. The secondary structure predicted for HSV contains 67% of its residues base-paired. The native HSV can possess an extended rod-...

Prospecting of local grapevine (Vitis vinifera L.) germplasm revealed that Tunisia possesses a rich patrimony which presents diversified organoleptic characteristics. However, viral diseases seriously affect all local grapevine cultivars which risk a complete extinction. Sanitation programs need to be established to preserve and exploit, as a gene pool, the Tunisian vineyards areas. The presenc...

Abstract An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological innovation. Herein, official changes virus taxonomy, including establishment megataxonomy amendments codes classification nomenclature, recently made by International Committee on Taxonomy Viruses were summarized. The continued effor...

Introduction The presence of double stranded RNA (dsRNA) in virus-infected tissue has been well documented by Morris and Dodds (4), Dodds and Bar-Joseph (2). The analysis of dsRNA proved to be useful for determining the virus-free status of propagation material after sanitation treatments. Isolated directly from grapevine, dsRNA is also a good source of viral RNA for synthesizing and cloning cD...

The analysis of the first plant genomes provided unexpected evidence for genome duplication events in species that had previously been considered as true diploids on the basis of their genetics. These polyploidization events may have had important consequences in plant evolution, in particular for species radiation and adaptation and for the modulation of functional capacities. Here we report a...

The analysis of the first plant genomes provided unexpected evidence for genome duplication events in species that had previously been considered as true diploids on the basis of their genetics. These polyploidization events may have had important consequences in plant evolution, in particular for species radiation and adaptation and for the modulation of functional capacities. Here we report a...

viroids are smallest, single-stranded, circular, highly structured plant pathogenic rnas that do not code for any protein. viroids belong to two families, the avsunviroidae and the pospiviroidae. members of the pospiviroidae family adopt a rod-like secondary structure. in this study the most stable secondary structures of citrus viroid variants that reported from fars province were drawn. the m...

The rolling circle replication of small circular plant pathogenic RNAs requires a processing step to convert multimeric intermediates to monomers which are then circularized. Eleven such RNAs are known so far, two are viroids, one is viroid-like and the remainder are satellite RNAs dependent on a helper virus for replication. The processing step is RNA-catalysed in all cases, at least in vitro....