A process of generating transgenic plants or plant cells transformed on their plastome, comprising (a) introducing into plant plastids a first DNA molecule and a second DNA molecule, wherein said first DNA molecule contains a first region homologous to a region of the plastome for directing plastome integration and a first sequence of interest, and said second DNA molecule contains a second region homologous to a region of the plastome for directing plastome integration and a second sequence of interest, whereby a sequence segment of said first sequence of interest is homologous to a sequence segment of said second sequence of interest, and selecting transformants having an integration sequence stably integrated in the plastome, whereby said integration sequence contains at least a portion of said first and at least a portion of said second sequence of interest as a continuous sequence.