DIVERSITY OF CITRUS TRISTEZA VIRUS IN JAMAICA
L. Fisher, P. Tennant, W.A. McLaughlin
Citrus tristeza virus (CTV), one of the most serious pathogens affecting Rutaceae species, causes considerable economic losses to citrus production worldwide. While mild pathotypes have been known for many years in Jamaica, decline outbreaks were only recently recognized after the introduction of the vector Toxoptera citricidus in 1993. In this study, coat protein (CP) gene sequences of isolates from four major citrus-growing regions in Jamaica were obtained and their molecular diversity compared with reference CTV genotypes from other regions. CP sequences from Jamaican isolates showed identities between 90 to 100% at the nucleotide level and shared similar identities with comparable sequences reported for other Jamaican isolates in 2009 and 2010. Phylogenetic analysis revealed segregation into five of seven lineages. One third of the Jamaican isolates clustered with Florida-T30 and Spain-T385 genotypes, with 99 to 100% identity within the lineage. The remaining isolates grouped closely with Florida T36-like genotypes or with the grapefruit and orange stem pitting B249 from Venezuela and the New Zealand CTV-resistance breaking genotypes. Identities among these groups ranged between 91 and 99%. The detection of genetic variants and potential recombination events involving parents from different lineages provide further evidence of the diversity among Jamaican CTV isolates.