Abstract: The coding sequence of the chicken interferon gamma(ChIFN-γ)gene was optimized by modification of codon usage to that of Brassica napobrassica plant genes.The synthetic ChIFN-γ gene,along with an endoplasmic reticulum retention signal(SEKDEL),was placed under control of the Napin promoter and napin signal peptide in the plasmid with isocaudarner technique,pSH-NGN which transformed into Agrobacterium tumefaciens EHA105.The transient expression system utilizes lettuce(Lactuca sativa L.)vacuum-infiltrated with Agrobacterium tumefaciens.The ChIFN-γ transient expression level in lettuce was determined by enzyme-linked immunosorbent assay(ELISA).The results provide a basis for the next stage of stable genetic transformation of brassica napobrassica plants as an oral vaccine,simultaneously also provide a new method for efficient and rapid identification gene expression.