Polymorphism of a specific region in gene p23 of Citrus tristeza virus allows discrimination between mild and severe isolates.

摘要: The pathogenicity determinants of Citrus tristeza virus (CTV) are presently unknown, although transgenic Mexican limes over-expressing CTV p23, an RNA-binding protein involved in regulating the asymmetrical accumulation viral RNA strands, display typical symptoms. Here we compared predominant sequence variants gene p23 from 18 isolates different geographic origin and characteristics. Phylogenetic analysis these sequences revealed three groups isolates: i) mild, inducing only symptoms lime and/or decline citrus species grafted on sour orange rootstock, ii) severe, causing additionally stem pitting sweet grapefruit, iii) atypical group inciting variable located at periphery each were recombinants. Pairwise comparisons predicted amino acid showed that residues positions 78-80 characteristic isolates. Group-specific primers based differences allowed RT-PCR detection type dsRNA-rich preparations infected tissues. While mild contained this group, most severe their additionally, groups, suggesting phenotype is associated with presence types. This association can be exploited for quick potentially damaging monitoring cross protection.