Incidence and Molecular Characterization of Citrus psorosis virus in Tunisia

Abstract

In order to study the current situation of Citrus psorosis virus (CPsV) in Tunisia, field surveys were conducted in commercial orchards in Cap Bon region and 575 citrus trees were sampled. As determined by DAS-ELISA, the CPsV incidence in Tunisia was high, and ranged between 20 and 47%, according to geographical location, citrus species and varieties. cDNA encompassing the full-length RNA3 from Tunisian isolates was synthesized by RT-PCR using specific primers and two isolates were cloned and sequenced. Full length sequences of the coat protein (CP) gene were obtained and deposited in GenBank. Based on CP gene sequences, phylogenetic clustering of isolates revealed two populations, one includes isolates from Spain, Morocco and New Zealand and the other includes those from Tunisia, Spain, Italy, Mexico and Egypt. Genetic haplotype network provided evidence of the existence of two distinct clusters with an ambiguous origin. Selective neutrality test was significantly positive, suggesting a balancing selection of CPsV CP gene.

Keywords

• Citrus psorosis virus
• coat protein gene
• molecular variability
• recombination
• serology