SEMANCIK, J. S., L. K. GRILL, and E. L. CIVEROLO. 1978. Accumulation of viroid RNA in tumor cells after double infection by Agrobacterium tumefaciens and citrus exocortis viroid. Phytopathology 68: 1288-1292. The presence of citrus exocortis viroid (CEV) in tumors RNase-resistant ' I-CEV following molecular hybridization induced by A. tumefaciens in CEV-infected tomato has been of nucleic acid ...

Due to their small size, locating pathogenic RNAs, such as viroids, in plant tissue and cell organelles has been difficult. Viroids are circular single-stranded RNA virus-like pathogens that reduce growth, vigor, yield economically important crops potato, tomato, hops citrus. Viroid infections plants largely diagnosed by dot blot hybridization, PAGE-gels, or RT-PCR. Because traditional situ hyb...

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 infected...

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...

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...

Eggplant latent viroid (ELVd) can form stable hammerhead structures in its (+) and (-) strands. These ribozymes have the longest helices I reported in natural hammerheads, with that of the ELVd (+) hammerhead being particularly stable (5/7 bp are G-C). Moreover, the trinucleotide preceding the self-cleavage site of this hammerhead is AUA, which together with GUA also found in some natural hamme...

The Asiatic citrus psyllid (Diaphorina citri Kuwayama [Hemiptera: Sternorrhyncha: Psyllidae] is a vector of huanglongbing (citrus greening), a devastating disease of citrus caused by phloem-limited bacteria. Growing guava (Psidium guajava) as an intercrop appears to be a successful means of reducing psyllid numbers within citrus orchards; however, the mechanism by which such a reduction is achi...