The hygromycin phosphotransferase (denoted hpt, hph or aphIV) gene was originally derived from Escherichia coli. The gene codes for hygromycin phosphotransferase (HPT) , which detoxifies the aminocyclitol antibiotic hygromycin B. A large number of plants have been transformed with the hpt gene and hygromycin B has proved very effective in the selection of a wide range of plants, including monocotyledonous. Most plants exhibit higher sensitivity to hygromycin B than to kanamycin, for instance cereals.