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Field Evaluation of a Transgene Containment Strategy for Plant-Made Pharmaceuticals in Tobacco
H.M. Davies, O. Chambers, C. N.Stewart
Department of Plant and Soil Sciences
Plants used to manufacture pharmaceuticals and industrial proteins must not be able to transfer the genes encoding these products to the equivalent conventional crops. This project examines a genetic strategy for obviating, or greatly reducing the potential for, this 'gene flow' when tobacco plants are used as the production system.
2009 Project Description
The work conducted during the past year was undertaken by our UT collaborator, but with progress and plans shared with us (the UK team and P.I.) through monthly status reports and site visits at which detailed discussion and planning was undertaken. The UT team have progressed the generation of the required transgenic plants to the stage that suitable parents for the intended N. glauca - N. tabacum (TN-90) hybrids are in process of being selected by screening at whole-plant stage for the highest GFP-expressers. Following provision of transgenic GFP-expressing T1-generation plants from the UT team, we (the UK group) grew them and generated T2 seed via self-pollination.
The UT investigators are now growing plants from these T2 seeds, prioritizing the whole-plant-GFP lines GFP-1, GFP-2, GFP-3 (all these expressing 35S-GFP), to screen the resulting T2 N. glauca plants for quantitative GFP expression. The goal is to obtain and send us the best homozygous, high-expressing, plants from these for our forthcoming crosses to make hybrids. Having developed T0-generation fertile-TN90 35S-GFP N. tabacum plants, the UT team is self-pollinating them and will collect the resulting T1 seed, and grow plants. They will screen 10 events quantitatively for GFP expression and identify the highest GFP expressers. They will send 3-5 of the best plants to us for the hybridization.
In the next few months, upon receiving the selected parental lines from UT we will cross them and make the hybrids which will then be the subject of the planned field and greenhouse outcrossing experiments in Kentucky and Tennessee in the 2010 field season. Suitable locations to conduct the field trials have been identified, and work on permits is in process. The UT investigators continue to develop transgenic plants expressing a pollen-specific marker for the planned future experiments on pollen flow.
Production of the transgenic parental lines, which has experienced considerable delay (due in part to technical issues) is an essential first element of the overall project. The hybrid plants which the project is designed to evaluate are derived by crossing these N. glauca and N. tabacum parent-plants. With the parental lines now at whole-plant stage, being selected for optimal marker (GFP) expression, we are now only a few weeks or months away from being able to start producing the hybrid seed for the planned 2010 beginning of the outcrossing experiments.