Deacetylation of an inactive precursor of herbicide, N-acetyl phosphinothricin (N-AcPt) results in the active herbicide molecule, phosphinothricin (Pt). This process was applied on plant as a negative selection system. I isolated E. coli ornithine deacetylase (argE) gene and expressed this gene in tobacco under the control of constitutive Cauliflower mosaic virus (CaMV) 35S promoter. The herbicide, Pt was acetylated and purified by evaporation of acetic acid. And I established successful green-house level negative selection system by using N-AcPt, which was harmless to nontransgenic tobacco and only destroyed argE transgenic tobacco transformant selectively.