The compositions and methods are provided that enhance the selection of
transgenic plants having two T-DNA molecules integrated into a plant
genome at different physical and genetic loci. The compositions are DNA
constructs that comprise novel arrangements of T-DNA molecules containing
genes of interest, positive selectable marker genes, and conditional
lethal genes. The methods disclosed herein comprises transforming a plant
cell to comprise the DNA constructs of the present invention,
regenerating the plant cell into a plant and identifying independant
transgene loci, where the selectable marker genes or transgenic elements
can be segregated in the progeny.