Table 1. Sequence of monomeric circular (+) RNAs accumulating in transgenic Arabidopsis expressing viroid dimeric (+) RNAs.

Viroid species	Primers*	Clones sequenced	Observed mutations
CEVd	75-95, 96-113	10	Two clones: C38→U, G287→U
HSVd	64-87, 88-109	6	None
	276-1, 2-23	6	Two clones: +A(39-45)
CCCVd	41-65, 66-90	9	None
ASSVd	79-89, 90-110	10	One clone: G29→Δ, C31→U, C210→U
ASBVd	42-57, 58-78	10	One clone: U148→C, C151→Δ
			One clone: G196→A

^*Positions of the viroid sequence covered by primers of (−) and (+) polarities, respectively, used for RT-PCR amplification.