viroid


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viroid,

microscopic infectious agent, much smaller than a virusvirus,
parasite with a noncellular structure composed mainly of nucleic acid within a protein coat. Most viruses are too small (100–2,000 Angstrom units) to be seen with the light microscope and thus must be studied by electron microscopes.
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, that infects higher plants such as potatoes, tomatoes, chrysanthemums, and cucumbers, causing stunted or distorted growth and sometimes death. It can be transmitted by pollen, seed, or farm implements. Viroids are single strands of RNA and lack the protein coat of viruses. They do not code for any specific protein but are able to replicate themselves in the nuclei of infected cells. Some scientists believe viroids are parts of normal RNA that have gone awry. Potato spindle tuber viroid was the first to be identified.

viroid

[′vī‚rȯid]
(microbiology)
The smallest known agents of infectious disease, characterized by the absence of encapsidated proteins.
References in periodicals archive ?
The archaea and viroids can regulate the nervous system including the NMDA/GABA thalamocorticothalamic pathway mediating conscious perception.
The effects of viroid infection first were noticed in the 1920s, but the cause remained unknown until uncovered in 1971.
The induction and accumulation of the pathogenesis-related P69 proteinase in tomato during citrus exocortis viroid infection and in response to chemical treatments.
The viroid nature of the cadang-cadang disease of coconut.
Another USDA scientist found the first viroid ever identified by scientists when studying potato spindle tuber disease, which is transmitted in tubers and seed.
Multiple virus and viroid detection and strain separation via multiplex reverse transcription-polymerase chain reaction.
Diener discovers the viroid, the smallest known agent of plant disease.
Vidhyasekaran (Tamil Nadu Agricultural University) describes 35 molecular diagnostic techniques for diagnosing fungal, bacterial, viral, phytoplasma, and viroid diseases, the various molecular marker- assisted breeding technologies, and transgenic plants with diseases- resistant genes.
When the boxes in [one viroid] are paired, a structure is generated in the viroid which is strikingly similar to that of group 1 introns," Dinter-Gottlieb writes.
Studies on the diagnosis of hop stunt viroid in fruit trees: Identification of new host and application of a nucleic acid extraction procedure based on nonorganic solvents.
In the first volume, Studies in Viral Ecology: Microbial and Botanical Host Systems, the 12 chapters define viral ecology and the basic biology of viruses, viral taxonomy, and morphology, replication, assembly, and evolutionary ecology, then viruses with microbial and plant hosting species, including bacteriophage and viral ecology as viewed through nucleic acid sequence data; viruses of cyanobacteria, eukaryotic algae, and seaweeds; the ecology and evolution of fungal, prion, and plant viruses, including geminiviruses; and viroids and viroid diseases of plants.