Introduction of bacterial metabolism into higher plants by polycistronic transgene expression

Multiple-gene transformation is required to improve or change plant metabol isms effectively; but this many-step procedure is time-consuming and costin g. We succeeded in the metabolic engineering of tobacco plants by introduci ng multiple genes as a bacteria-type operon into a plastid genome. The toba cco plastid was transformed with a polycistron consisting of three bacteria l genes for the biosynthesis of a biodegradable polyester, polyhydroxybutyr ate (PHB). Accumulation of PHB in the leaves of the transgenic tobacco indi cated that the introduced genes were polycistronically expressed. This "phy to-fermentation" system can be used in plant production of various chemical commodities and pharmaceuticals.