Two Novel Variants of Hop Stunt Viroid Associated with Citrus Diseases

Viroids are small, covalently closed, circular, single-stranded RNA molecules which contain 246-463 nucleotides and have no protein coat or mRNA activity. In citrus a series of viroid-like RNA in the range of 275-375 nt was reported with different infectivity on a group of citrus indicator hosts. The authors wish to thank the Council of Centers of Excellence and the Iranian Chapter of TWAS (ISMO) for supporting this research.