Plastics produced by bacterial fermentation are degradable in many different environ-ments and comprised of renewable resources, making them a "green" alternative to their petroleum-based cousins. A major barrier to commercialization, however, is their high cost. Producing these biopolymers in genetically engineered plants has long been viewed as a way of reducing these costs, but progress has been slow. Now in this issue, Gruys and colleagues describe synthesis of a particularly useful plastic in plants, by engi-neering four bacterial genes to modify two different metabolic pathways ( see p. 1011 and Research News p. 960 ).