Polyhydroxybutyrate (PHB) is a biodegradable polyesters (bioplastics) naturally produced by many bacteria. Production of PHB in plants could provide a solar-energy-powered source of bioplastic. However, economically viable production of bioplastics in plants tends to have detrimental effects on growth, which limits the use of plants as bio-factories. To develop a high PHA- yielding plant, it is critical to systematically study the metabolic effects of addition of new genes. This dissertation describes metabolic consequences of bioplastic accumulations in Arabidopsis and switchgrass. In addition, to quantify acetyl-CoA and other acyl-coenzymeAs in plants, a new LC-MS-MS based method has been developed and reported in this dissertation. To better understand switchgrass metabolism, metabolite profiles of switchgrass and Arabidopsis were compared.

PHB-accumulating lines of switchgrass and the model plant Arabidopsis have been generated. Metabolite profiles (non-targeted GC-MS analysis), the acyl-CoAs accumulations (LC/MS/MS), and transcriptomic profiles were compared between PHB accumulating plants and control plants. Transcriptomic and metabolomic data were evaluated using exploRase (MetNet Platform, http://metnetDB.org) software to analyze and visualize omics data.

Using systems biology approaches, this study help to understand the metabolic changes upon bioplastic accumulation in plants. The understanding from this study would help finding the way to optimize bioplastic accumulation in Arabidopsis and switchgrass, and also provide a step toward to understand systematic changes upon foreign material accumulation in plant.