EXTRACTION OF NUCLEI FROM SONCHUS YELLOW NET RHABDOVIRUS-INFECTED PLANTS YIELDS A POLYMERASE THAT SYNTHESIZES VIRAL MESSENGER-RNAS AND POLYADENYLATED PLUS-STRAND LEADER RNA

Although the primary sequence of the genome of the plant rhabdovirus s onchus yellow net virus (SYNV) has been determined, little is known ab out the composition of the viral polymerase or the mechanics of viral transcription and replication. In this paper, we report the partial is olation and characterization of an active SYNV polymerase from nuclei of SYNV-infected leaf tissue, A salt extraction procedure is shown to be an effective purification step for recovery of the polymerase from the nuclei, Full-length, polyadenylated SYNV N and M2 mRNAs and plus-s trand leader RNA are among the products of the in vitro polymerase rea ctions, Polyadenylation of the plus-strand leader RNA in vitro is show n with RNase H and specific oligonucleotides, This is the first report of a polyadenylated plus-strand leader RNA for a minus-strand RNA vir us, a feature that may reflect adaptation of SYNV to replication in th e nucleus, Analysis of the SYNV proteins present in the polymerase ext ract suggests that the N, M2, and I, proteins are components of the tr anscription complex. Overall, the system we developed promises to be u seful for an in-depth characterization of the mechanics of SYNV RNA sy nthesis.