SUBGENOMIC RNAS OF BAMBOO MOSAIC POTEXVIRUS-V ISOLATE ARE PACKAGED INTO VIRIONS

Purified virions of bamboo mosaic potexvirus-V isolate (BaMV-V) were f ound to contain three major RNA species, the 6.4 kb genomic RNA and tw o RNAs of 2.0 and 1.0 kb, in addition to associated satellite RNA (0.8 5 kb). Results of Northern blot hybridization, primer extension analys is and cDNA sequencing showed that the packaged 2.0 and 1.0 kb RNAs of BaMV-V were subgenomic RNAs. In contrast, in the BaMV-O isolate, only genomic RNA was packaged and encapsidated subgenomic RNAs were not de tectable. The transcription initiation sites for the 2.0 and 1.0 kb su bgenomic RNAs of BaMV-V were located 11 and 16 nt upstream of the init iation codon of open reading frames (ORFs) 2 and 5, respectively. The 2.0 and 1.0 kb subgenomic RNAs functioned as messengers for the ORF2 p rotein and capsid protein, respectively. Packaging of the 1.0 kb subge nomic RNAs resulted in the formation of rod-shaped particles about 70 nm in length. Our results indicate that BaMV isolates have evolved dis tinctly for packaging of subgenomic RNAs.