GENOME CHARACTERIZATION AND TAXONOMY OF PLANTAGO-ASIATICA MOSAIC POTEXVIRUS

The complete nucleotide sequence of Plantago asiatica mosaic virus (Pl AMV) genomic RNA has been determined. The 6128 nucleotide sequence con tains five open reading frames (ORFs) coding for proteins of M(r) 156K (ORF1), 25K (ORF2), 12K (ORF3), 13K (ORF4) and 22K (ORF5). The sequen ces of these PlAMV proteins exhibit strong homology to the proteins of the other potexviruses. Phylogenetic trees based on the multiple sequ ence alignments of three conserved domains in ORF1 product and capsid protein reveal a close relationship of PlAMV to papaya mosaic virus an d clover yellow mosaic virus. The PlAMV genomic RNA and a major subgen omic RNA (sgRNA) of 0.9 kb have been detected in infected leaves by No rthern blot hybridization. The latter sgRNA is the messenger for virus capsid protein and its 5' terminus has been located 23 nucleotides up stream of the initiator codon of the coat protein gene. The PlAMV viri on RNA and RNA transcript resembling the 0.9 kb sgRNA have been transl ated in vitro giving rise to a single major 170K product and a major 2 2K product, respectively.