Comparison of nucleotide sequences from three potato leafroll virus (PLRV)isolates collected in Brazil

Polymerase chain reaction linked automated sequencing was used to compare t he relatedness of Brazilian (BR) potato leafroll luteovirus (PLRV) isolates , By comparing PLRV genomic sequences from Holland, Poland, Canada, Scotlan d, and Australia (GeneBank), three primer pairs were designed and made that would hybridize to all five isolates, and amplifying three variable region s which display distinctive nucleotide variations in each isolate. These pr imer pairs mere used in the reverse-transcription polymerase chain reaction (RT-PCR) to analyze analogous variable regions in three PLRV isolates hom around Sao Paulo State, BR (two from field potatoes grown 500 km apart, one hom Datura stramonium), Each primer pair amplified a DNA product of predic ted size from the BR isolates and a Wisconsin (USA) isolate, and all PCR pr oducts were directly sequenced. Comparisons of the variable region sequence s from the three Brazilian isolates to the five isolates from GenBank and t he one from Wisconsin revealed that the BR isolates were approximately 99% homologous with each other, 97% with the European and Canadian isolates, an d 95% with the USA and Australian isolates. These results suggest that the primer pairs utilized in this study can be used to detect PLRV (by RT-PCR) for diagnostic purposes, and can further be used to differentiate between d ifferent PLRV isolates (when RT-PCR is Linked to automated sequencing) for epidemiological purposes.