An environmental friendly and non toxic method for selection of transformed cells from a population consisting of transformed and non-transformed cells. The method comprises the following steps a) introducing into a cell at least one desired nucleotide sequence and at least one selection-nucleotide sequence to obtain a genetically transformed cell, wherein the selection-nucleotide sequence comprises a region which codes for a protein involved in the metabolizing of trehalose; b) placing a population with transformed and non-transformed cells into contact with trehalose and/or derivative thereof; and c) selecting the transformed cells from the population on the basis of the capacity of the transformed cells to metabolize the trehalose and/or derivative.