Molecular characterization of the 3′ end of Citrus tristeza virus genome from Oman

Citrus aurantifolia (acid lime) trees exhibiting yellowing, stem pitting and decline symptoms in Oman were found to be infected by Citrus tristeza virus (CTV) (genus; Closterovirus, family; Closteroviridae). The sequence of the 3′ approximately 9.8 Kb genome, encompassing the partial RNA dependent RNA polymerase to P23 genes including the 3′ UTR region was determined. Pairwise nucleotide comparisons revealed that the Oman isolate had the highest nucleotide identity with those from Mexico and Egyptian isolates. Phylogenetic analysis showed that the Oman isolate clustered with the Egyptian isolate and was identified as T36 genotype. Recombination analysis showed the presence of three potential recombination events and the findings of this study are discussed. Further, extensive studies on CTV species mainly in Oman and as a whole in the Arabian Peninsula is needed, especially after investigating the recombinant 3′ CTV genome isolate.