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Identification and Characterization of a Variant of Citrus viroid V (CVd-V) in Seminole Tangelo

2010; Volume: 17; Issue: 17 Linguagem: Inglês

10.5070/c534m1b2xq

0074-7203

Pedro Serra, J. A. Pina, N. Durán-Vila,

Phytoplasmas and Hemiptera pathogens

Previous studies on Atalantia citroides, a citrus relative that appeared to be immune to viroid infection, revealed the existence of a new viroid, which was designated tentatively as Citrus viroid-V (CVd-V) and has been proposed as a new member of the genus Apscaviroid within the family Pospiviroidae.Biological indexing of a Seminole tangelo tree on the Etrog citron indicator followed by sPAGE analysis revealed the presence of a viroid that has been characterized as a new variant of CVd-V.The variant has 97.6% sequence identity with the reference sequence of CVd-V and shows three characteristics: (i) two compensatory changes that modify an A-U base pair between the upper and lower "strands" into a G-C base pair, (ii) a U→A change located in a loop that does not seem to disturb the viroid secondary structure, and (iii) two sets of changes located in the upper and lower strands that result in a rearrangement of the base pairing between the upper and lower strands.Infectivity studies performed with an artificial mutant revealed the existence of structural constraints in the region in which major differences between CVd-V and the Seminole tangelo variant were identified.