A new sequence variant of Coleus blumei viroid 1 from the Coleus blumei cultivar "Rainbow Gold'

A viroid was isolated from symptomless Coleus blumei cultivar (cv.) 'Rainbow Gold' plants using the bidirectional PAGE method for analysis of small circular RNA molecules. The viriod was transmitted to viroid-free plants of Coleus blumei cv. 'Scarlet Dragonfly' by mechanical inoculation. Cloning and sequencing revealed that the viriod from the Coleus cv. 'Rainbow Gold' is closely related to the Coleus blumei viriod 1-BvA (CbVd 1-BvA) isolated from the Coleus cv. 'Bienvenue'. Therefore, new viroid sequence variant has been named Coleus blumei viriod 1-RG (CbVd 1-RG). Coleus blumei viriod 1-RG consists of 251 nucleotides, 140 G + C, 111 A + U with a GC content of 55.4%. The most stable rod-like secondary structure of this viroid has 53 G:C, 29 A:U and 5 G:U base pairs with a minimum free energy (at 25 degrees C) of -81.2 kcal/mol (-339.4 kJ/mol). The right terminal domain shows a high sequence similarity to the corresponding domain of hop latent viroid (HLVd).