The 3'-nucleotide sequence of an ordinary strain of potato virus S.

The sequence of 1346 nucleotides of the 3'-terminal region of an ordinary strain of potato virus S was determined from cloned cDNA. This portion of the viral RNA contains two major open reading frames (ORFs), encoding the coat protein of M(r)33K and a protein of M(r)11K 3' to the coat protein, both of which showed high homology, 93% and 79%, respectively, with the equivalent proteins of the Andean strain. A major block of amino acids that differ between the ordinary and Andean strains was present in both the coat protein and the 11K. These blocks may be responsible for the substantial differences between the ordinary and Andean strains at the symptom and aphid transmissibility levels.