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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.
2010 Project Description
- Conducted the first of the two seasonal field experiments employing the transgenic plants developed in the first phase of the project.
- Obtained required regulatory approval, and planted the outcrossing experiment in the chosen field sites in Tennessee and Kentucky.
- Monitored and recorded the performance of the plants from the onset of flowering.
- Collected all seed pods that formed on the hybrid plants, and sampled pods from the positive-control plants.
- Recorded morphological appearance of pods on the hybrids, as well as seed content.
- Attempted to germinate all seed-like entities from the hybrid pods, and germinated seed samples from the indicator-plant pods.
- Examined resulting seedlings under UV light to assess and record possible expression of marker transgene.
- Continued to prepare transgenic plants expressing markers genes in both foliar and pollen tissues for next season's (2012) field experiment, screening them for optimal expression using both antibiotic selection and quantitative fluorescence estimation of marker phenotype.
- Prioritized transgenic plants for crossing to make the hybrids for the 2012 experiment.
This field 'outcrossing' experiment was the first of two field trials which comprise the purpose of the overall project, i.e. to assess the suitability of the Nicotiana interspecific hybrid plants for production of new materials in a transgenic format without compromising the genetic integrity of other tobacco-type crops being grown (for any applications, including production of other new materials) in the adjacent environment.
The study will also serve to illustrate how the development of new host plants exhibiting limited fertility can help address concerns about the use of transgenic crops to provide much-needed new pharmaceuticals and industrial materials, as the customization of the host plant itself for such applications has received very little attention in the past (with any crop species).
In addition to contributing the first of two replicated sets of data (replication over two seasons being necessary to provide confidence in the reproducibility of the results in different seasonal conditions), the field experiment also enabled the investigators to become familiar with the performance of the plants outdoors and to become proficient in the required use of pollen traps and seed sampling/testing techniques. These experiences will help ensure an even more successful experiment next year.