PHA production, from bacteria to plants

The genes encoding the polyhydroxyalkanoate (PHA) biosynthetic pathway in R alstonia eutropha (3-ketothiolase, phaA or bktB; acetoacetyl-CoA reductase, phaB; and PHA synthase, phaC) were engineered for plant plastid targeting and expressed using leaf (e35S) or seed-specific (7s or lesquerella hydroxy lase) promoters in Arabidopsis and Brassica. PHA yields in homozygous trans formants were 12-13% of the dry mass in homozygous Arabidopsis plants and a pproximately 7% of the seed weight in seeds from heterozygous canola plants . When a threonine deaminase was expressed in addition to bktB, phaB and ph aC, a copolyester of 3-hydroxybutyrate and 3-hydroxyvalerate was produced i n both Arabidopsis and Brassica. (C) 1999 Elsevier Science B.V. All rights reserved.