Beyond Corn and Soybean - Transgenic Traits in Wheat and Sorghum.

The University of Nebraska-Lincoln has established the infrastructure for the development and agronomic evaluation of transgenes in commodity crops.  The infrastructure collectively referred to as the agriculture biotechnology pipeline, consists of a plant transformation core research facility coupled with a plant biotechnology field facility.  The former possesses the wherewithal for the genetic engineering of the major commodity crops, including soybean, sorghum, wheat and maize, while the latter is dedicated acreages for the field-testing of regulated transgenic events.  With respect to grains, sorghum and wheat, our efforts are targeting strategies to improve nitrogen use efficiency (NUE), tolerance to abiotic stresses and end-use functionality.  In regards to NUE, we have assembled and introduced, via Agrobacterium-mediated transformation into both wheat and sorghum, a series of plant expression cassettes that harbor transgenes involved in nitrogen storage and flux in planta, namely the rice cytosolic glutamine synthetase (OsGS1) and plastidic NADH-glutamate synthase (OsGAGAT), along with the barley alanine aminotransferase (HvAlaAT).  In addition, we are exploring a transcription factor strategy by introducing the maize Dof1 (ZmDof1) transcription factor as a means to coordinately express multiple genes linked to carbon/nitrogen flux in planta.  The end-use target in sorghum being evaluated involves modulating storage proteins.  To this end we have successfully silenced both the gamma kafirin and the 22 kDa alpha kafirin, and expressed a wheat high molecular weight glutenin subunit.  These target seed storage protein modifications were done independently and were subsequently stacked by crossing, hence, we now have sorghum germplasm in which silenced gamma kafirin, 22 kDa alpha kafirin and production of the wheat high molecular weight glutenin subunit traits are present individually and in combinatorial stacks.  The end-use target for wheat is modification of fructans via the introduction of the levansucrase (sacB) gene from Bacillus subtilis for the production of levan in the grain.