A method of controlling a genetically-modified plant, comprising (a) providing a genetically-modified plant, whereby cells of said genetically-modified plant contain a heterologous nucleic acid and whereby said genetically-modified plant is inactive with regard to a cellular process of interest, (b) switching on said cellular process of interest by directly introducing a polypeptide from a cell-free composition into cells containing said heterologous nucleic acid wherein said polypeptide and said heterologous nucleic acid are mutually adapted such that said polypeptide is capable of switching on said cellular process of interest.