Write a note on viroids?

Hint: viroids are the plant pathogen that has short, circular, single-stranded RNA. In them, the RNA is present without the protein coat. Viroids are extremely small in size. Their RNA does not code for any protein. Viroids are dependent on the plant virus for their replication.

Complete answer:
viroids are small in size and have single-stranded circular RNA present in them. They have a small sequence of RNA which have less than a thousand base pairs. They have RNA which do not code for any protein substances. They depend on the plant viruses for their replication and encapsidation. Viroids were discovered by Theodor Otto Diener who was a plant pathologist. They were discovered and named by the same scientist in the year 1971. The first viroid which was discovered was of the potato spindle tuber viroid (PSTVd). The viroid’s replicated by the enzyme RNA polymerase II. They are different from the viruses as they have an absence of a protein coat. The mature viroids are able to infect plants and cause diseases in them. It leads to an economic loss of the plant they cause disease in. The viroid’s when infecting a plant they utilize proteins of the host plant for their basic biological functions like replication, processing, transport, and pathogenesis.

Note: viroids are the smallest pathogens known to humans. They only infect the plant and cause diseases in them. They are not found to be infectious in humans or animals. They have single-stranded RNA and have an absence of the protein coat on them. They do not encode for any protein but are able to replicate when introduced into host plant varieties.