Production of high levels of poly-3-hydroxybutyrate in plastids of Camelina sativa seeds.

Poly-3-hydroxybutyrate (PHB) production in plastids of Camelina sativa seeds was investigated by comparing levels of polymer produced upon transformation of plants with five different binary vectors containing combinations of five seed-specific promoters for expression of transgenes. Genes encoding PHB biosynthetic enzymes were modified at the N-terminus to encode a plastid targeting signal. PHB levels of up to 15% of the mature seed weight were measured in single sacrificed T1 seeds with a genetic construct containing the oleosin and glycinin promoters.

PHA bioplastics, biochemicals, and energy from crops.

Large scale production of polyhydroxyalkanoates (PHAs) in plants can provide a sustainable supply of bioplastics, biochemicals, and energy from sunlight and atmospheric CO(2). PHAs are a class of polymers with various chain lengths that are naturally produced by some microorganisms as storage materials. The properties of these polyesters make them functionally equivalent to many of the petroleum-based plastics that are currently in the market place.

High levels of bioplastic are produced in fertile transplastomic tobacco plants engineered with a synthetic operon for the production of polyhydroxybutyrate.

An optimized genetic construct for plastid transformation of tobacco (Nicotiana tabacum) for the production of the renewable, biodegradable plastic polyhydroxybutyrate (PHB) was designed using an operon extension strategy. Bacterial genes encoding the PHB pathway enzymes were selected for use in this construct based on their similarity to the codon usage and GC content of the tobacco plastome. Regulatory elements with limited homology to the host plastome yet known to yield high levels of plastidial recombinant protein production were used to enhance the expression of the transgenes.

Production of polyhydroxybutyrate in switchgrass, a value-added co-product in an important lignocellulosic biomass crop.

Polyhydroxyalkanoate bio-based plastics made from renewable resources can reduce petroleum consumption and decrease plastic waste disposal issues as they are inherently biodegradable in soil, compost and marine environments. In this paper, the successful engineering of the biomass crop switchgrass (Panicum virgatum L.) for the synthesis of polyhydroxybutyrate (PHB) is reported.

Chemically inducible expression of the PHB biosynthetic pathway in Arabidopsis.

Arabidopsis plants were transformed with a multi-gene construct for expression of the polyhydroxybutyrate (PHB) biosynthetic pathway containing a gene switch that can be activated by commercially available non-steroidal ecdysone analogs approved for use on some crops as pesticides. T(1) progeny of transgenic Arabidopsis plants were isolated and screened for PHB production in the presence of ecdysone analogs. T(2) progeny derived from selected T(1) lines were subjected to further analysis by comparing PHB production levels prior to treatment with inducing agent and 21 days after initiation of induction.

Polyhydroxyalkanoate polymers and their production in transgenic plants.

Commercialization of plant-derived polyhydroxyalkanoates will require the creation of transgenic crop plants that possess high product yields, normal plant phenotypes, and transgenes that are stable over several generations. The studies included in this review describe the progress that has been made toward achieving these goals in both model plant systems and commercial crop plants.