The vitamin E family of antioxidants in plants consists of tocotrienols and tocopherols.  These molecules differ only in the degree of unsaturation of their isoprenoid-derived tail.  Because of their lipid soluble nature, tocotrienols and tocopherols are extracted as components of vegetable oils during the commercial processing of seeds.  These molecules confer improved oxidative stability to vegetable oils, which is important for food processing and for engine and hydraulic lubrication.  The goal of these studies was to metabolically engineer increased content of vitamin E antioxidants in soybean seeds, which would subsequently be used for functionality testing.  Transgenic soybean lines were generated that express a cDNA for barley homogentisate geranylgeranyl transferase (HGGT) under control of the seed-specific promoter for the alpha' subunit of beta-conglycinin.   As demonstrated in our previous studies, HGGT catalyzes the first step in the biosynthesis of the tocotrienol form of vitamin E in monocot seeds, and transgenic expression of this enzyme alone is sufficient to confer tocotrienol biosynthetic ability to plant cells.  Transgenic events were obtained that accumulate vitamin E antioxidants to amounts >2,500 microgram/gram seed wt, which is a >6-fold enhancement in vitamin E content relative to seeds from non-transformed plants  This is currently the highest content of vitamin E antioxidants engineered in seeds of crop plants by use of a single transgene.  These increases were due largely to the production of delta- and gamma-tocotrienols.  In a second experiment, the barley HGGT transgene was co-expressed in soybean along with a seed-specific transgene for the gamma-tocopherol/tocotrienol methyltransferase.  Seeds obtained from transgenic lines contained similar levels of increased vitamin E content as observed for expression of HGGT alone, however the composition was shifted to primarily the beta- and alpha-forms of tocotrienol.  We are currently bulking seed from homozygous lines for functionality testing of extracted vegetable oils.