Abstract Hop stunt viroid (HSVd) and Citrus tristeza virus (CTV) are the causal agents of most important diseases of citrus. Previously we reported a novel variant of HSVd that constantly associated with the yellow corky vein disease. Here, 19 individual citrus leaves with yellow corky vein symptoms were sampled for CTV by ELISA. In this study, most symptomatic samples were found to be inf...

At present isolates of Hop stunt viroid (HSVd) are divided into five groups: three major groups (plum-type, hop-type and citrus-type) each containing isolates from only a limited number of isolation hosts and two minor groups that were presumed to derive from recombination events between members of the main groups. In this work we present the characterization of 16 new sequence variants of HSVd...

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 small self-replicating RNAs that infect plants. How these noncoding pathogenic RNAs interact with hosts to induce disease symptoms is a long-standing unanswered question. Recent experimental data have led to the suggestive proposal of a pathogenic model based on the RNA silencing mechanism. However, evidence of a direct relation between key components of the RNA silencing pathway an...

Hop stunt was a mysterious disorder that first emerged in the 1940s in commercial hops in Japan. To investigate the origin of this disorder, we infected hops with natural Hop stunt viroid (HpSVd) isolates derived from four host species (hop, grapevine, plum and citrus), which except for hop represent possible sources of the ancestral viroid. These plants were maintained for 15 years, then analy...

A large body of evidence has lead to the suggestive proposal of a potential interplay between viroid-induced pathogenesis and RNA silencing regulatory mechanisms. A variety of techniques have been used to examine this interaction. This chapter outlines the use of a green fluorescent protein (GFP) sensor, containing viroid-specific sequence targets to study this phenomenon. In addition, a sympto...

BACKGROUND Viroids are circular, highly structured, non-protein-coding RNAs that, usurping cellular enzymes and escaping host defense mechanisms, are able to replicate and move through infected plants. Similarly to viruses, viroid infections are associated with the accumulation of viroid-derived 21-24 nt small RNAs (vd-sRNAs) with the typical features of the small interfering RNAs characteristi...

Eukaryotic organisms exposed to adverse conditions are required to show a certain degree of transcriptional plasticity in order to cope successfully with stress. Epigenetic regulation of the genome is a key regulatory mechanism allowing dynamic changes of the transcriptional status of the plant in response to stress. The Hop stunt viroid (HSVd) induces the demethylation of ribosomal RNA (rRNA) ...