Enzyme inhibitors to increase poly-3-hydroxybutyrate production by transgenic tobacco.

Chemical regulation of secondary-metabolite synthesis was investigated through the improvement of poly-3-hydroxybutyrate (PHB) production in transgenic tobacco plants by the use of enzyme inhibitors. Two tobacco lines, BC3 and rCAB8, that produce PHB in both the cytosol and plastids were used. An acetyl-CoA carboxylase inhibitor, D-(+)-Quizalofop-ethyl, increased PHB accumulation in both lines 2-fold. The accumulation rate of plastidial PHB in the rCAB8 line was 2.5-fold higher than that of cytosolic PHB in the BC3 line. A specific inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, mevastatin, also increased PHB accumulation but only in the BC3 line. These results indicated that chemical regulation of the native metabolic flows by the specific enzyme inhibitors increased secondary-metabolite production in the transgenic tobacco plants we used.