viroids

Viroids are tiny, infectious particles composed solely of a short strand of circular, single-stranded RNA. Unlike viruses, they lack a protein coat and do not encode proteins. Viroids infect plants, disrupting their normal functions and causing various plant diseases. They replicate within the host plant's cells by hijacking the plant’s own cellular machinery, often leading to symptoms like stunted growth, deformed leaves, or reduced fruit production. Because of their simple structure and mode of action, viroids are an intriguing example of how infectious agents can be purely genetic material without additional proteins or shells.