Presence of necrotic strains of Potato virus y in Mexican potatoes

Abstract

As part of a routine screening for the possible presence of the necrotic strains of potato virus Y affecting potatoes in Mexico, five PVY isolates were submitted to biological and molecular analysis. Considering their serological properties, two belong to the common strain (O) and three to the necrotic strain (N). All the isolates induced vein necrosis in Nicotiana tabacum. To characterize the isolates, 5' NTR and P1 genes were sequenced and compared with sequences from GenBank database. Nucleotide sequence similarity ranged from 47100% in the 5' NTR and from 63100% in the P1 coding region. The lowest amino acid similarity between sequences of P1 gene was 55%. In phylogenetic trees of 5'NTR analysis, two PVYOMexican isolates clustered with other PVYOisolates. In turn, the three PVYNisolates grouped with PVYN-NTNisolates. The phylogenetic analysis of P1 sequences (nucleotide and amino acid) showed two PVYOisolates grouping next to N-NTN cluster. A detailed analysis of the PVYOisolates showed two potential recombination regions in the P1 gene, in contrast to 5'NTR where no recombination was detected. © 2009 Ramírez-Rodríguez et al; licensee BioMed Central Ltd.