Abstract
The nucleotide sequence and secondary structure of two representative variants from the Group III citrus viroids. CVd-IIIa (297 bases) and CVd-IIIb (294 bases) were determined. The variants are related to the apple scar skin viroid (ASSVd) family. Although smaller in size than any of the ASSVd-related viroids, the central conserved region as well as most of the terminal conserved region of ASSVd is retained. The rod- like structural configuration (characteristic of ASSVd) of the variants as predicted by minimum free energy analysis is presented.