Molecular cloning of a potato virus Y genome: nucleotide sequence homology in non-coding regions of potyviruses.

An aphid-transmissible field isolate of potato virus Y, strain MM, was purified from a pepper host and cloned. All but 18 terminal nucleotides of the 9.7 kb genome are apparently contained in two overlapping cDNA clones. The library of cDNA clones is likely to be representative of the viral RNA population present in infected plants because restriction endonuclease maps derived from cloned and uncloned cDNA are colinear, each region of the genome is represented by several independent clones, and nucleic acid sequencing of 5' and 3'-terminal regions revealed small AU-rich non-coding domains with blocks of nucleotide sequence homology between this strain of PVY and three other potyviruses. The efficient application of cDNA cloning techniques to a large positive-stranded RNA virus is described.