Viroids and viroid-like satellite RNAs from plants, and the human hepatitis delta virus (HDV) RNA share some properties that include small size, circularity and replication through a rolling-circle mechanism. Replication occurs in different cell compartments (nucleus, chloroplast and membrane-associated cytoplasmatic vesicles) and has three steps: RNA polymerization, cleavage and ligation. The ...

TAXONOMY Potato spindle tuber viroid (PSTVd) is the type species of the genus Posipiviroid, family Pospiviroidae. An absence of hammerhead ribozymes and the presence of a 'central conserved region' distinguish PSTVd and related viroids from members of a second viroid family, the Avsunviroidae. PHYSICAL PROPERTIES Viroids are small, unencapsidated, circular, single-stranded RNA molecules which...

Citrus canker and Huanglongbing (HLB) are citrus diseases that represent a serious threat to the citrus production worldwide and may cause large economic losses. In this work, we combined fluorescence imaging spectroscopy (FIS) and a machine learning technique to discriminate between these diseases and other ordinary citrus conditions that may be present at citrus orchards, such as citrus scab ...

The demonstration of enzymatic capabilities of certain RNAs, in addition to their well-known template properties, has led to the recognition that RNAs are the only biological macromolecules that can function both as genotype and phenotype, hence raising the possibility of Darwinian selection and precellular evolution at the RNA level in the absence of DNA or protein. Recent models of such prece...

Viroids are a unique class of noncoding RNAs: composed of only a circular, single-stranded molecule of 246-401 nt, they manage to replicate, move, circumvent host defenses, and frequently induce disease in higher plants. Viroids replicate through an RNA-to-RNA rolling-circle mechanism consisting of transcription of oligomeric viroid RNA intermediates, cleavage to unit-length strands, and circul...

Peanut stunt virus-associated RNA 5 (PARNA 5), the satellite of a plant cucumovirus, is a linear RNA of 393 nucleotides with a 5' cap and a 3' hydroxyl group. Determination of its nucleotide sequence has revealed two consecutive open reading frames that together extend most of its length. Sequences at the 5' and 3' ends are homologous with those of the satellite of the related cucumber mosaic v...

Viruses are ubiquitous and present in a wide range of settings, from living organisms to various environments. Although viruses are regarded as important pathogens in higher plants, viral populations in specific host plants have not yet been fully examined. This study revealed viral populations in grape berries obtained from a cultivar from a single vineyard using currently available grapevine ...

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-...

Comprehensive next generation sequencing virus detection was used to detect the whole spectrum of viruses and viroids in selected grapevines from the Czech Republic. The novel NGS approach was based on sequencing libraries of small RNA isolated from grapevine vascular tissues. Eight previously partially-characterized grapevines of diverse varieties were selected and subjected to analysis: Chard...