Compositions for enhancing segregation of transgenes in plants
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 independent transgene loci, where the selectable marker genes or transgenic elements can be segregated in the progeny.
1. A DNA plasmid comprising in linked order a first Agrobacterium Ti plasmid right border region operably linked to a first DNA region comprising at least one transgene of agronomic interest operably linked to a second Agrobacterium Ti plasmid right border region operably linked to a second DNA region comprising an antibiotic positive plant selectable marker transgene or a herbicide positive selectable marker transgene and plasmid maintenance elements required for propagation in bacteria, wherein said second DNA region is also operably linked to said first Agrobacterium Ti plasmid right border region.
2. The DNA plasmid of claim 1 , wherein said second DNA region further comprises a conditional lethal transgene.
3. The DNA plasmid of claim 2 , wherein said conditional lethal transgene is selected from the group consisting of: phosphonate monoester hydrolase, glyphosate oxidoreductase, carboxy ester hydrolase, N-acetyl-L-ornithine deacetylase, P450 monooxygenase CPY105A1, and β-glucuronidase.
4. The DNA plasmid of claim 1 , wherein said antibiotic positive plant selectable marker transgene provides tolerance to an antibiotic is selected from the group consisting of hygromycin, kanamycin, bleomycin, G418, streptomycin and spectinomycin.
5. The DNA plasmid of claim 1 , wherein said herbicide selectable marker transgene provides tolerance to a herbicide selected from the group consisting of glyphosate, glufosinate, sulfonylureas, imidazolinones, bromoxynil, delapon, cyclohezanedione, a protoporphyrinogen oxidase inhibitor, and isoxaslutole herbicides.
6. The DNA plasmid of claim 1 , wherein said transgene of agronomic interest provides an agronomic trait comprising herbicide tolerance, increased yield, insect control, fungal disease resistance, virus resistance, nematode resistance, bacterial disease resistance, mycoplasma disease resistance, modified oils production, high oil production, high protein production, germination and seedling growth control, enhanced animal and human nutrition, low raffinose, environmental stress tolerance, increased digestibility, industrial enzyme production, pharmaceutical peptides and small molecule production, improved processing traits, proteins improved flavor, nitrogen fixation, hybrid seed production, reduced allergenicity, biopolymers, or biofuel production.
7. The DNA plasmid of claim 1 , wherein said plasmid maintenance elements comprise at least one origin of replication and an antibiotic marker.
8. The DNA plasmid of claim 7 , wherein said origin of replication is a pBR322 origin of replication and/or an oriV origin of replication from the RK2 plasmid.
9. The DNA plasmid of claim 7 , wherein said antibiotic marker is an aad (Spc/Str) gene for bacterial spectinomycin/streptomycin resistance.