Selection of Streptomyces viridochromogenes DSM 40736 against phosphinothricyl-alanyl-alanine (PTT) results in PTT-resistant selectants. The DNA fragment which harbours the phosphinothricin (PTC) resistance gene is obtained from the complete DNA of these selectants by cutting with BamHI, cloning of a 4.0 kb fragment and selection for PTT resistance. This gene is suitable for producing PTC-resistant plants as well as resistance markers.
