In order to transform pokeweed antiviral protein cDNA to tobacco plant, total RNA was extracted from Phytolacca americana. PAP-II cDNA was synthesized from purified total RNA via RT-PCR and subcloned to recombinant vector pBluescript II SK-. 10 deletion mutant PAP-II cDNA fragments which were sequentially deleted from N-terminal by 90bp were synthesized from PAP-II cDNA except leading frame by PCR with primers designed in our laboratory. To select non-cytotoxic clone, pAc55M was constructed with yeast expression vector pAc55 and multicloning site(MCS). Sequentially deleted mutant PAP-II cDNAs were cloned on downstream of gall promoter of pAc55M. 6 non-cytotoxic deletion mutant PAP-II cDNA were selected. Selected cDNAs were cloned into plant expression vector pKGT101BH for transformation of these clones to plant through Agrobacterium tumefacience. After cloning, recombinant pKGT101BH carrying deleted mutant PAP-IIcDNA were transformed to Nicotiana tabacum cv. NC567. Transformed tobacco plants cultured on shooting and rooting media were transfered to green-house. About four weeks later, these plants were infected with physically infection using carborandum with PVY-VN strain. After 4 weeks, plants resistant to virus were selected , and seeds of these plants were gathered. Southern blot hybridization showed deleted fragments by 220bp and 420bp, so resistant ability of these plants is due to mutant PAP-II cDNA