MOLECULAR CHARACTERIZATION OF AN ISOLATE OF CITRUS TRISTEZA VIRUS THAT CAUSES SEVERE SYMPTOMS IN SWEET ORANGE

摘要: The complete sequence (19,249 nucleotides) of the genome citrus tristeza virus (CTV) isolate SY568 was determined. organization is identical to that previously determined CTV-T36 and CTV-VT isolates. Sequence comparisons revealed CTV-SY568, a severe stem-pitting from California, has more than 87% overall identity with CTV-VT, seedling yellows Israel. Although an 81% CTV-T36, quick decline Florida, in 3′ half over 90% while 5′ as low 56%. Based on alignments these three isolates, sequences are generally well conserved, relatively divergent. data independent overlapping clones CTV-SY568 two regions highly divergent sequences. In open reading frame 1b (RNA dependent RNA polymerase), there were 118 nucleotide differences lead 16 amino acid changes. coat protein gene, 5 changes result 48 differences. Most occurred third position codons, resulted silent substitutions. RNase protection assays demonstrated most obtained representative major species this isolate. Northern analysis indicated accumulated viral including genomic certain subgenomic RNAs isolates VT or T36 sweet orange.