Grouping of Potato Isolates of PVY Based on thr 5'-UTR Nucleotide Sequence

Abstract

Potato isolates of Potato virus Y (PVY) were divided into two major groups based on nucleotide sequence
homology in the 5’-end region of their genomes. Several characteristic nucleotide modifications differentiated the
two virus groups. Sequence similarity within members of each group was 89–100%, whereas between members of the
respective groups there was sequence divergence of up to 33%. The two groups were distinguished by restriction
cleavage of the virus PCR products elicited by group-specific restriction endonucleases: Xho II and Nsp I (group I)
and Mbo II, Fok I and Nco I (group II). The sites of the first three enzymes (group I-specific) were sequentially
positioned so that a sequence of 16 nucleotides preceding the ATG codon could be determined in this way. Group I
included members of the tobacco necrotic (N) and non-necrotic (O) strains of PVY, whereas the potato tuber necrotic
isolate NTN-H belonged to the second group, which included also non-tuber and tobacco leaf necrotic members. It
seems therefore that the biological characteristics of the tuber or tobacco leaf necrosis are not related to nucleotide
modifications at the 5’-UTR but rather to group-specific differences.