We studied temporal and spatial expression patterns of the potato proteinase inhibitor II(PI-II) promoter, using transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) plants that carried of fusion between the PI-II promoter and the chloramphenicol acetyltransferase (cat) gene. PI-II promoter activity was low when plants were young, but increased as plants grew. In 8-week-old plants, old leaves showed higher activity than young leaves. At flowering stage (ca. 15 weeks), the overall promoter activity was reduced to a lower level except in the petals. Compared with stems or petioles at the flowering stage, the roots and floral organs showed minimal activity for the PI-II promoter. We used several environmental stimuli to examine the induction of the PI-II promoter in different organs. Promoter induction was effected by wounding or methyl jasmonate in stems, petioles, sepals, and leaves. The induction was highest in leaves, as was sucrose-enhanced wound induction. These results suggest that the PI-II gene is temporally and spatially regulated. We also established a transient assay system in tobacco BY2 suspension cells to elucidate the upstream regulatory region of the PI-II promoter. A field strength of 0.75 kV/cm and 400 $mu$F capacitance were optimal electroporation conditions for our transient assay.