A wound-inducible proteinase inhibitor I gene was isolated from a genomic library and characterized at the nucleotide sequence level previously. In order to understand the molecular biology of wound induction of the inhibitor I gene, the inhibitor I-chloramphenicol acetyltransferase (CAT) chimaeric genes were constructed in a vector derived from Ti plasmid of Agrobacterium tumefaciens. One of the constructs, pJSL105 was introduced into tobacco cells by electroporation, which were regenerated into intact plants. Southern hybridization of genomic DNAs isolated from leaves of a transgenic plant revealed the presence of the plasmid DNA. Agrobacterium-mediated transformation of tobacco was also carried out with pJSL105. Leaf segments were co-cultivated with Agrobacterium containing pJSL105 mobilized from E. coli by triparental mating. Kanamycin-resistant colonies initiated at the boundary of leaf segments were regenerated into plants. The functionality of the wound-inducible promoter of the inhibitor I gene is being tested by CAT assay.