The sequence of 1, 392 nucleotides from the 3'-terminal genomic region of aphid transmissible isolate 1 and that of 1, 103 nucleotides from the 3' region of non-transmissible isolate 31 of turnip mosaic virus (TuMV) RNA were determined. These sequences contained the complete coding region of the coat protein followed by a 3' non-coding region of 209 nucleotides. The coat protein genes of these two isolates were 864 nucleotides long, encoding 288 amino acids of Mr 33, 061 (isolate 1) or Mr 33, 132 (isolate 31). A putative glutamine-alanine cleavage site was identified at the N-termini of the coat proteins of the two isolates. Nucleotide sequence comparison of the coat protein genes of the two isolates revealed 20 nucleotide substitutions which give rise to 6 amino acid differences near the N-termini. The amino acid sequence of the coat protein of TuMV isolate 1 was 47.6 to 58.3% homologous to those of 11 other potyviruses, with most of amino acid conservation found in the C-terminal regions. The nucleotide sequence of 3' non-coding region of TuMV isolate 1 was 28.3 to 37.8% homologous to those of 11 other potyviruses.