Infectious cDNA clones of four viroids in Coleus blumei and molecular characterization of their progeny

Four viroid species infecting Coleus blumei, named Coleus blumei viroid 1-4 (CbVd-1-CbVd-4), and two tentative new viroid species,. named CbVd-5 and CbVd-6, have been characterized, for two of which (CbVd-5 and CbVd-6, first reported in 2009), there is no established bioassay. Here, infectious clones were used as inoculums sources and the biological properties of CbVd-1, -3, -5 and -6 were assessed. When dimeric CbVd (+) RNAs synthesized in vitro were bioassayed, the first detection time for the four CbVds was different, ranging from 45 to 300 days. In addition, we confirmed that CbVd-5 and CbVd-6 can be transmitted via seeds. Molecular characterization of their progeny from slash-inoculated plants one year after inoculation demonstrated that the genetic diversity of CbVd populations may depend on the infected coleus plants and on the viroid genotype. (C) 2013 Elsevier B.V. All rights reserved.