Introduction of bacterial metabolism into higher plants by polycistronic transgene expression.

Multiple-gene transformation is required to improve or change plant metabolisms effectively; but this many-step procedure is time-consuming and costing. We succeeded in the metabolic engineering of tobacco plants by introducing multiple genes as a bacteria-type operon into a plastid genome. The tobacco plastid was transformed with a polycistron consisting of three bacterial genes for the biosynthesis of a biodegradable polyester, polyhydroxybutyrate (PHB). Accumulation of PHB in the leaves of the transgenic tobacco indicated that the introduced genes were polycistronically expressed. This "phyto-fermentation" system can be used in plant production of various chemical commodities and pharmaceuticals.