Sequencing of peach latent mosaic viroid variants from nine North American peach cultivars shows that this RNA folds into a complex secondary structure.

We sequenced 34 new peach latent mosaic viroid (PLMVd) variants isolated from nine different peach cultivars. This study provides the widest view of PLMVd diversity reported to date and includes the original characterization of North American variants, which cannot be differentiated from European sequences. PLMVd appears as a species in which each isolate is a complex mixture of RNAs. Analysis of base-pair covariations supports the hypothesis that PLMVd folds into a complex branched structure with the potential of including three new pseudoknots. The resulting "globular-like" structure is in contrast to the rod-like one adopted by most other viroids. Copyright 2000 Academic Press.