The invention relates to a method for producing a transformed plant cell. More particularly, the method involves the transformation of a plant cell with a Transformation Cassette which is targeted to plant plastids and which comprises a selection gene, for example isopentenyl transferase (IPT), and a transgene. After selection for transformed plastids, expression of a recombinase is induced in the plant cell, which leads to the excision of the selection gene from the plastid and the expression of the transgene in the plastid. The invention also provides cells and plants comprising the Transformation Cassette.