Both point mutation and RNA recombination contribute to the sequence diversity of citrus viroid III

Citation
Ra. Owens et al., Both point mutation and RNA recombination contribute to the sequence diversity of citrus viroid III, VIRUS GENES, 20(3), 2000, pp. 243-252
Citations number
42
Categorie Soggetti
Molecular Biology & Genetics
Journal title
VIRUS GENES
ISSN journal
09208569 → ACNP
Volume
20
Issue
3
Year of publication
2000
Pages
243 - 252
Database
ISI
SICI code
0920-8569(200005)20:3<243:BPMARR>2.0.ZU;2-O
Abstract
Field-grown citrus trees often harbor complex mixtures of 4-5 different vir oid species, and the presence of citrus viroid III (CVd-III) has been shown to reduce the rate of tree growth without inducing disease. To more fully define the structure of its quasi-species, we have examined nine citrus vir oid complexes for the presence of previously undescribed sequence variants of CVd-III. Analysis of 86 full-length cDNAs generated from these nine viro id complexes by RT-PCR revealed the presence of 20 new CVd-III variants. Ch ain lengths ranged from 293-297 nucleotides, and sequence changes were conf ined largely to the lower portions of the central conserved region and vari able domain. The previously described variants CVd-IIIa (297 nt) and CVd-II Ib (294 nt) were clearly predominant, but phylogenetic analysis indicated t hat certain isolates may contain representatives of two additional fitness peaks. At least one group of CVd-III variants appears to have arisen as a r esult of RNA recombination. Populations recovered from diseased/declining t rees were the most diverse, but even dwarfing isolates originating from old line Shamouti trees showed considerable variability.