The method is for introducing a gene of antiviral protein PIP expressed in Phytolacca insularis Nakai. The method comprises isolating the pure gene from cDNA library, preparing recombinant expression vector pJMC201 containing the gene and transforming a plant cell with the vector. mRNA is isolated and purified from leaf of Phytolacca insularis Nakai and then cDNA library is prepared. Then, with PAP gene isolated from leaf of Phytolacca americana L. as probe, pure PIP gene is isolated and deletion mutant thereof is made. By dideoxy chain termination method, total base sequence of the gene is determined and PIP gene is amplified by polymerase chain reaction. By cloning the gene into a binary vector pBI121, recombinant expression vector pJMC201 is prepared. Thereafter, the vector is introduced into Agrobacterium tumefaciens LBA4404. This Agrobacterium and plant tube disc are cultured simultaneously, by which the plant is transformed.
