RNA-DEPENDENT RNA-POLYMERASE FROM PLANTS INFECTED WITH TURNIP CRINKLEVIRUS CAN TRANSCRIBE (-STRANDS AND (-)-STRANDS OF VIRUS-ASSOCIATED RNAS())

RNA-dependent RNA polymerase (RdRp) was solubilized from membranes of turnip infected with turnip crinkle virus (TCV), a single-stranded, mo nopartite RNA virus. The RdRp activity could be separated into three p eaks by Sephacryl S5OOHR chromatography. RdRp from peak I, which conta ined substantial amounts of endogenous TCV genomic RNA, and peak II we re template-specific, synthesizing full-length complementary strands o f exogenous TCV subviral RNAs but not control RNA templates. Peak III RdRp was nonspecific, synthesizing full-sized products for all added R NA templates. Peak II RdRp transcribed several different TCV satellite (sat) and defective interfering RNA templates in both (+)- and (-)-se nse orientations but did not transcribe (+)-strands of satellite RNAs associated with unrelated viruses. Monomeric-length sat-RNA C was synt hesized from a template containing as many as 220 nonsatellite bases a t the 3' ends of either (+)- or (-)-strands, indicating that the RdRp was able to recognize 3'-end sequences in an internal location. Deleti on of 95-242 bases from the 3' end of (+)-strand sat-RNA C abolished t he synthesis of template-length product. However, transcription of tem plate-length products was not affected by the deletion of at least 257 bases from the 3' end of (-)-strand sat-RNA C template (leaving only the 100 5'-terminal residues), implying that different mechanisms exis t for synthesis of (+)-and(-)-strand satellite RNA in vitro.