Citrus viroid V: Molecular characterization and synergistic interactions with other members of the genus Apscaviroid

• Published in: Virology (New York, N.Y.) N.Y.), 2008-01, Vol.370 (1), p.102-112
• Main Authors: Serra, P, Barbosa, C.J, Daròs, J.A, Flores, R, Duran-Vila, N
• Format: Article
• Language: English
• Subjects: Base Sequence; CBLVd; Citrus - growth & development; Citrus - virology; Citrus bent leaf viroid; Citrus viroid V (CVd-V); Citrus viroids; CVd-III; Infectious Disease; Molecular Sequence Data; Nucleic Acid Conformation; Phylogeny; Plant Diseases - virology; Plant Leaves - virology; Plant Viruses - classification; Plant Viruses - genetics; Plant Viruses - pathogenicity; Sequence Analysis, DNA; Species Specificity; Synergism; Viroids - classification; Viroids - genetics; Viroids - pathogenicity; Viroids - physiology
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2007.07.033

Abstract Studies on Atalantia citroides , a citrus relative, revealed the existence of a viroid not described previously. The new viroid has a GC-rich genome of 293–294 nucleotides and contains the central conserved region characteristic of members of the genus Apscaviroid , and the terminal conserved region present in this and other genera of the family Pospiviroidae . The secondary structure of minimum free energy predicted for the new viroid is a rod-like conformation with 68.7% paired nucleotides and showing sequence identities with other viroids always lower than 90%, the conventional limit that separates different species within a given genus. Infectivity assays showed that the new viroid induces mild but characteristic symptoms on the indicator Etrog citron. Co-inoculation of CVd-V with either Citrus bent leaf viroid or Citrus viroid III , two other members of the genus Apscaviroid infecting citrus, disclosed synergistic interactions manifested in enhanced leaf symptoms and very pronounced dwarfing. Viroid titers, however, remained unaltered in co-infected plants. Possible mechanisms underlying the observed synergistic effects are discussed. According to its molecular and biological properties and its unusual ability to replicate in A. citroides , the new viroid, tentatively named Citrus viroid V (CVd-V), should be considered a new species of the genus Apscaviroid.