Nucleotide sequence and secondary structure of potato spindle tuber viroid

The viroid of the potato spindle tuber disease (PSTV) is a covalently closed ring of 359 ribonucleotides. As a result of intramolecular base pairing, a serial arrangement of double-helical sections and internal loops form a unique rod-like secondary structure. PSTV is the first pathogen of a eukaryotic organism for which the complete molecular structure has been established.