NUCLEOTIDE-SEQUENCE AND INFECTIVITY OF A FULL-LENGTH CDNA CLONE OF PANICUM MOSAIC-VIRUS

The sequence of an infectious cDNA clone of panicum mosaic virus (PMV) showed that the single-stranded RNA genome is 4326 nucleotides (nt) a nd a single highly abundant subgenomic (sg) RNA of 1475 nt was synthes ized during PMV infection of pearl millet plants and protoplasts. Comp uter comparisons revealed strong similarities between the predicted am ino acid sequences of the p48 and p112 open reading frames (ORFs) and replicase proteins of members of the Tombusviridae. The sgRNA has the potential to encode five proteins. Three small ORFs, p8, p8-FS, and/or p6.6 have similarity to ORFs of carmo-, necro-, and machlomoviruses t hought to be involved in virus spread in plants. The sgRNA also has th e potential to encode a 26-kDa capsid protein and a 15-kDa nested gene (p15) of unknown function. PMV transcripts also supported replication and movement of SPMV, the satellite virus. Genome organization, physi cochemical properties, and biological features indicate that PMV is a member of the Tombusviridae family. However, PMV differs sufficiently from previously described members to warrant its placement in a new ge nus provisionally designated Panicovirus. (C) 1998 Academic Press.