The invention concerns a method for obtaining a transgenic monocotyledon plant containing a gene of interest free of foreign ancillary sequences, comprising the following steps: a) transforming at least a plant cell free of active transposase, with a vector comprising two expression cassettes, one (i) including a nucleotide sequence of interest, the other (ii) including a nucleotide sequence coding for a selection marker framed by the mobilisable sequences of a transposon; b) selecting plants transformed with the selection marker (ii); cross-breeding a transformed plant with another plant belonging to a line containing in its genome a gene, coding for an endogenous active transposon, and which is in the middle of an excision phenotypic marker (iii) to obtain a F1 or any other individual of subsequent generation; d) selecting cells of individual carriers of the gene of interest free of foreign ancillary sequence, from the F1 generation; e) regenerating plants from the cells or individuals selected in (d).
