Abstract
Citrus Tristeza Virus (CTV) is the most economically important virus of citrus worldwide. Genetic diversity and population structure of CTV isolates from all citrus growing areas from Uruguay were analyzed by RT-PCR and cloning of the three RNA silencing suppressor genes (p25, p20 and p23). Bayesian phylogenetic analysis revealed the circulation of three known genotypes (VT, T3, T36) in the country, and the presence of a new genetic lineage composed by isolates from around the world, mainly from South America. Nucleotide and amino acid identity values for this new genetic lineage were both higher than 97% for the three analyzed regions. Due to incongruent phylogenetic relationships, recombination analysis was performed using Genetic Algorithms for Recombination Detection (GARD) and SimPlot software. Recombination events between previously described CTV isolates were detected. High intra-sample variation was found, confirming the co-existence of different genotypes into the same plant. This is the first report describing: (1) the genetic diversity of Uruguayan CTV isolates circulating in the country and (2) the circulation of a novel CTV genetic lineage, highly present in the South American region. This information may provide assistance to develop an effective cross-protection program.
Highlights
Citrus is one of the most important commercial fruit crop worldwide
The co-circulation of different Citrus Tristeza Virus (CTV) genotypes and the possibility of re-infection caused by the Population Structure and Geographical Distribution of CTV Isolates in Uruguay virus vector, we analyze the DNA clones obtained from the Uruguayan isolates, in order to know a
331 DNAcaused clones the virus vector, we analyze the DNA clones obtained from the Uruguayan isolates, in order to know a genome regions of thirteen CTV isolates, establishing phylogenetic relationships between them
Summary
Citrus is one of the most important commercial fruit crop worldwide. Citrus Tristeza Virus (CTV)is the most serious viral pathogen of citrus and has been responsible for the loss of over 100 million trees in the past 70 years [1]. Toxoptera citricida and Aphis gossypii, the former being the most efficient in virus transmission [2]. It is graft transmitted and is limited to the phloem of infected plants species of Rutaceae [3]. CTV virions (Closteroviridae, Closterovirus) are flexuous filaments of 2000 ˆ 11 nanometers in size, with a helical nucleocapsid architecture consisting of two coat proteins One of these proteins is a 25 kDa major capsid protein (CP), which forms a long virion body covering 95% of the particle length and is encoded by the p25 gene [4,5,6].
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