PURPOSE: A plant virus RNA vector useful for transformation of plant cell, obtained by replacing a coat protein gene range of tobamovirus with an adventitious gene.

CONSTITUTION: Plasmid pBR325 containing chloramphenicol acetyltransferase (CAT) gene derived from Escherichia coli HB101 strain is treated with restriction enzyme to construct pCL29 (A) having a coat protein gene range of tobacco mosaic virus (TMV) of pLFW3 replaced with CAT gene. On the other hand a fragment of pt5L29 is linked to a fragment of ptC3L5-2 to construct pCLB29 (B). Then the components A and B are digested with MluI, subjected to transcription reaction with Escherichia coli RNA polymerase and prepared RNA is purified by phenol extraction and ethanol precipitation.