Abstract: A method of selecting genetically transformed cells from a population of cells comprising introducing a desired nucleotide sequence and a co-introduced nucleotide sequence into the genome of a cell whereby the desired nucleotide sequence or the co-introduced nucletoide sequence induces a positive effect by giving the transformed cells a competitive advantage when the population of cells are supplied with an inactive compound thereby allowing the transformed cells to be identified and selected from the non-transformed cells by means defined as positive selection; as well as cells transformed according to the method and plants derived therefrom. The invention further relates to novel glucuronide compounds including cytokinin glucuronide compounds for use in the method.