sali xbai fragment of pb3rs2 interior to the bmv coat gene was then replaced by the approximately 0 6 kb mboii xbal fragment of pcc8c5 which contains the entire coat protein gene of tmv cc including sequences believed to represent the encapsidation origin of the rna meshi et al supra the sali and mboii restriction fragment ends were both repaired to blunt ends with t4 dna polymerase prior to ligation the resulting plasmid will be referred to as pb3 tmv transcripts from ecori linearized pb3 tmv including the complete bmv rna3 and tmv sequences contained in that plasmid were inoculated onto barley protoplasts along with infectious transcripts of bmv rna1 and rna2 cdna clones french et al 1986 science 231 1294 1297 the pb3 tmv rna 39 s were replicated in such infections and gave rise to a subgenomic rna of the size expected for a mrna initiated at the normal bmv rna3 subgenomic initiation site and containing all sequences between that point and the 3 39 end of the bmv rna sequence including the tmv cc sequence insertion rna samples were derived from protoplasts inoculated with transcripts of wild type cdna copies of bmv rna 39 s 1 and 2 and either no additional transcript or transcripts of either wild type bmv rna3 cdna or pb3 tmv fluorographs of 3huridine labelled rna 39 s separated on a 1 w v agarose gel after extraction from protoplast samples variously inoculated and incubated for 20 hours in light at 24 degrees c showed the presence of all these rna 39 s when.