Increased α-tocopherol content in soybean seed overexpressing the Perilla frutescens γ-tocopherol methyltransferase gene

• Published in: Plant cell reports Vol. 26; no. 1; pp. 61 - 70
• Main Authors: Tavva, Venkata S, Kim, Yul-Ho, Kagan, Isabelle A, Dinkins, Randy D, Kim, Kyung-Hwan, Collins, Glenn B
• Format: Journal Article
• Language: English
• Published: Berlin Berlin/Heidelberg : Springer-Verlag 01.01.2007; Springer
• Subjects: alpha-tocopherol; alpha-Tocopherol - chemistry; alpha-Tocopherol - metabolism; Amino Acid Sequence; Biological and medical sciences; Biotechnology; Blotting, Northern; Blotting, Southern; chemical constituents of plants; Chromatography, High Pressure Liquid; Fundamental and applied biological sciences. Psychology; gamma-tocopherol; Gene Expression Regulation, Plant; gene overexpression; Genetic engineering; Genetic technics; Glycine max; Glycine max - genetics; Glycine max - metabolism; Lipid Peroxidation; Malondialdehyde - metabolism; Methods. Procedures. Technologies; methyltransferases; Methyltransferases - genetics; Methyltransferases - metabolism; Molecular Sequence Data; Molecular Structure; Perilla frutescens; Perilla frutescens - enzymology; Perilla frutescens - genetics; Plants, Genetically Modified; promoter regions; seeds; Seeds - genetics; Seeds - metabolism; Sequence Alignment; soybean oil; soybeans; Transgenic animals and transgenic plants; Transgenic plants; vitamin E; Vitamin E - metabolism; Enzyme; Transferases; HPLC chromatography; Gene overexpression; Lipid peroxidation; Lipids; α-Tocopherol; Perilla frutescens; E-Vitamins; Soybean; Glycine max; Leguminosae; Gene; Methyltransferases; Dicotyledones; Angiospermae; Spermatophyta; Transgenic plant; γ-Tocopherol methyltransferase Transgenic plants Vitamin E; HPLC; Peroxidation
• ISSN: 0721-7714; 1432-203X
• DOI: 10.1007/s00299-006-0218-2

Tocopherols, with antioxidant properties, are synthesized by photosynthetic organisms and play important roles in human and animal nutrition. In soybean, γ-tocopherol, the biosynthetic precursor to α-tocopherol, is the predominant form found in the seed, whereas α-tocopherol is the most bioactive component. This suggests that the final step of the α-tocopherol biosynthetic pathway catalyzed by γ-tocopherol methyltransferase (γ-TMT) is limiting in soybean seed. Soybean oil is the major edible vegetable oil consumed, so manipulating the tocopherol biosynthetic pathway in soybean seed to convert tocopherols into more active α-tocopherol form could have significant health benefits. In order to increase the soybean seed α-tocopherol content, the γ-TMT gene isolated from Perilla frutescens was overexpressed in soybean using a seed-specific promoter. One transgenic plant was recovered and the progeny was analyzed for two generations. Our results demonstrated that the seed-specific expression of the P. frutescens γ-TMT gene resulted in a 10.4-fold increase in the α-tocopherol content and a 14.9-fold increase in the β-tocopherol content in T2 seed. Given the relative contributions of different tocopherols to vitamin E activity, the activity in T2 seed was calculated to be 4.8-fold higher than in wild-type seed. In addition, the data obtained on lipid peroxidation indicates that α-tocopherol may have a role in preventing oxidative damage to lipid components during seed storage and seed germination. The increase in the α-tocopherol content in the soybean seed could have a potential to significantly increase the dietary intake of vitamin E.