What does viroid mean?
A viroid is an exceptionally small infectious agent made only of a short, usually circular strand of RNA. It differs fundamentally from a virus because it has no protein coat and contains no genes for producing structural proteins. Viroids occur most notably in plants, where they can cause diseases characterized by stunting, leaf abnormalities, poor fruit development, and reduced crop yields. They may spread through infected plant material, mechanical injury, or vectors such as aphids. Scientists recognized the viroid as a distinct type of pathogen in the early 1970s while investigating potato spindle-tuber disease. The term is useful because it identifies an infectious entity outside the traditional virus category: a naked RNA molecule capable of causing disease. In modern biological and agricultural writing, viroid therefore denotes both a particular RNA pathogen and, collectively, this unusual class of infectious agents.
nounA viroid is a small infectious agent consisting solely of short, usually circular, single-stranded RNA. Unlike a virus, it has no protein coat or structural proteins and is known chiefly as a pathogen of plants.
- An infectious, usually circular, single-stranded RNA molecule that lacks a protein coat and primarily infects plants.
"The diseased potatoes carried a viroid that caused severe stunting and distorted growth."
"Researchers detected a viroid in the imported fig plants and quarantined the shipment."
"Viroids can spread through infected propagation material, making them an important concern for commercial plant nurseries."
Used for multiple viroids, whether referring to distinct RNA molecules, types, or infections.
"Several viroids can occur together in the same infected plant."
A viroid is a pathogen made only of RNA: a tiny infectious molecule that can nevertheless stunt, deform, or otherwise damage a plant.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of viroid
The word was coined in the early 1970s by plant pathologist Theodor O. Diener for the unusual infectious agent responsible for potato spindle-tuber disease. It combines “virus” with the Greek-derived suffix “-oid,” conveying the idea of a virus-like infectious entity. “Virus” itself comes from Latin, originally meaning poison or harmful material, and is also the source of words such as virulent, virulence, and virology.
How viroid is actually used
Viroid is a specialized biological term used in plant pathology, virology, and molecular biology. It is normally used attributively, as in “viroid RNA,” and has no established figurative use.
Easily confused with viroid
A virus contains RNA or DNA enclosed in a protein coat, whereas a viroid consists only of a small, usually circular RNA molecule.