Submitted to: Maydica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/6/2009
Publication Date: 12/15/2009
Publication URL: http://www.maiscoltura.it/maydica/articles/54_199.pdf
Citation: Wang, K., Frame, B., Xu, X., Moeller, L., Lamkey, K., Wise, R.P. 2009. Strategies for the Production of Maize-derived Pharmaceuticals using Cytoplasmic Male Sterile Lines: in vitro Tissue Culture/Transformation and Field Breeding Approaches. Maydica. 54(1):199-210. Interpretive Summary: Plant-made pharmaceuticals offer great promise for the treatment of human and animal diseases. However, pollen drift is considered a source of potential contamination of pharmaceuticals in the food chain. We describe two strategies for using cytoplasmic male sterile (cms-T) germplasm in open-field production of transgenic maize producing a pharmaceutical product. One strategy is to directly introduce the transgenes into transformable male-sterile germplasm. This is the first report of successful transformation of such male-sterile lines using the biolistic (gene gun) or Agrobacterium-mediated methods. The second strategy involves transfer of the subunit vaccine gene from a fertile transgenic line to a cms-T B37 background. After six seasons of breeding, male-sterile transgenic maize seed can be used for open-field production using a non-transgenic pollen donor to produce seeds for large-scale recombinant protein recovery, 100% of which contain the subunit vaccine gene. Plant-made pharmaceuticals offer great promise as efficient and cost-effective products for the treatment of human and animal diseases. The creation of an efficient male-sterile system for production of these pharmaceuticals protects growers and consumers against potential contamination in the food chain, while significantly reducing the cost of production.
Technical Abstract: Plant-made pharmaceuticals (PMPs) offer great promise as efficient and cost-effective products for the treatment of human and animal diseases. Maize seed is known for its large storage capacity and stability of proteins and starches; hence, it is considered an ideal organ for manufacturing recombinant proteins such as antigens and antibodies. Other advantages of the maize system include safety, high yields, and scalability of production and processing. However, the benefits of this technology must be balanced against potential health and environmental risks that may be associated with its use. Because PMPs presently have no provision for regulatory tolerances, their inadvertent occurrence in foods and feeds remains an important economic consideration, even when the health and environmental risks are low. Pollen drift is considered a source of potential contamination of maize-made pharmaceuticals in the food chain. In addition to physical and temporary isolation requirements, open field pharmaceutical maize production also calls for controlled pollen release. Here, we describe two strategies to eliminate the problem of transgenic pollen drift. First, we show the development of a tissue culture-amenable male-sterile line that allows direct introduction of transgenes via biolistic or Agrobacterium-mediated transformation. The second strategy involves the introgression of a transgene from male-fertile transgenic maize to male-sterile germplasm by conventional breeding. After six seasons of breeding, this second strategy allows us to obtain 100% transgenic seeds from an open-field production using a non-transgenic line as the pollinator.