Plants are a major source of fine chemicals (secondary metabolites) including pharmaceuticals, fragrances, flavors, and pesticides. Although there has been but limited success in the profitable production of secondary products from plant cultures there is serious interest in the use of plant cell and tissue culture for the production of these valuable commodities. Many of these products are produced by roots, so the use of plants transformed by Agrobacterium, yielding hairy roots, offers great potential for comercial exploitation. Hairy roots are genetically stable, grow rapidly, and produce levels of secondary products equal to or greater than the whole plant. Root hairs, however, are easily damaged in conventional bioreactors. A further barrier to the use of these plant tissues on a commercial scale is that most secondary metabolites accumulate within the plant tissue and are not readily exported into the growth medium. Thus, there is a need for nondestructive methods for culturing hairy roots and methods by which the products produced by these plant tissues can be recovered for processing while still retaining the biomass. The goals of the proposed research are to grow hairy roots of beets (Beta vulgaris) in a new bioreactor which employs nutrient mists, and to test physical techniques for the reversible permeabilization of cells for release of products into the medium. The proposed research will lay the groundwork for development of a unique model system for the large scale growth of plant hairy roots and development of techniques for the recovery of commercially valuable products (secondary metabolites) from these specialized plant tissues.
