This invention provides a genetic construct comprising: (a) a DNA cut-and-paste transposon genetic unit which comprises a transposase gene flanked on either side by inverted repeat sequences and operably under the control of a first promoter; and (b) a transgene unit which comprises an expressable transgene, placed operably under the control of a second promoter; wherein the transposon genetic unit and the transgene unit are linked with one of the inverted repeat sequence located in an intron of the transgene. This invention also provides methods of transiently expressing a transgene in a stably transformed eukaryote. This invention further provides methods for obtaining marker-free transgenic plants.