The invention relates to a method of producing transgenic plant material by transforming a plant with a vector comprising an essential gene having mutations at two sites at least. The method is exemplified with EPSPS as the essential gene. The method makes it possible to use an antisense molecule directed to the native form of said gene for selection of transformed plants. The application relates further to a plant obtainable by the method, a binary vector system containing the mutated essential gene, said mutations being silent mutations. Furthermore, the application discloses the use of an antisense molecule directed to an essential gene as a herbicide in particular using an aqueous solution comprising a saccharide such as sucrose, fructose and glucose.