Genetic evidence of potential virulent Citrus tristeza virus isolates in Mediterranean areas.

Abstract

Citrus tristeza virus (CTV) is the causal agent of devastating epidemics that have changed the course of citrus industry worldwide. Sixty-eight Mediterranean and eight exotic CTV isolates were characterized based on sequence divergence within the 5’ terminal genomic region and the major coat protein gene (CP). Different genotype profiles were assigned to each of the isolates examined according to their specific signals against a set of reaction to selected molecular markers. High sequence polymorphism in the CP region was observed from various CTV isolates between and within countries. Results indicated that T30 mild strain genotype was a stable viral component among the isolates under investigations. CP haplotypes showed high nucleotide identities with standard strains associated with high virulence behavior, such as T3 and SY568 while severe VT and T36 genotypes were the main variants in the Middle East and East Adriatic regions, respectively. The possible rapid diffusion of these severe CTV strains by aphids raises the risk of new outbreaks in the Mediterranean region.