What are Viroids?

Hint: Plant pathogens with short, circular, single-stranded RNA are known as viroids. The RNA is present in them without the protein covering. Viroids have a very small size. Their RNA does not include any protein-coding sequences. The replication of viroids is reliant on the plant virus.

Complete answer:
Viroids are tiny particles that contain single-stranded circular RNA. They have a short RNA sequence with fewer than a thousand base pairs. They have RNA, but it does not code for any protein. Plant viruses are responsible for their replication and encapsidation. Theodor Otto Diener, a plant pathologist, was the first to discover viroids. In 1971, they were discovered and named by the same scientist. The viroid of the potato spindle tuber was the first to be discovered (PSTVd). The enzyme RNA polymerase II replicates the virus. They are distinct from viruses in that they do not have a protein covering. The adult viroids are capable of infecting plants and infecting them with illnesses. It results in a financial loss for the plant they infect. When a viroid infects a plant, it uses the host plant's proteins for basic biological processes such as replication, processing, transport, and disease.

Additional information:
Difference between viroids and virus-
Viroids lack an exterior envelope and a capsid, and they can only proliferate within the host cell.
Proteins are not produced by viruses. They only make a single RNA strand, whereas viruses make proteins.
Viroids are made up of nucleic acid without a protein coat, whereas viruses are made up of nucleic acid with a protein coat.

Note:
The smallest pathogens known to humans are viroids. They only harm the plant by infecting it and causing illnesses. Humans and animals have not been found to be infected with them. They have single-stranded RNA and don't have a protein covering on them. They do not encode for any proteins, yet when introduced into host plant species, they can multiply.