Metabolically engineered oilseed crops with enhanced seed tocopherol

• Published in: Metabolic engineering Vol. 7; no. 5; pp. 384 - 400
• Main Authors: Karunanandaa, Balasulojini, Qi, Qungang, Hao, Ming, Baszis, Susan R., Jensen, Pamela K., Wong, Yun-Hua H., Jiang, Jian, Venkatramesh, Mylavarapu, Gruys, Kenneth J., Moshiri, Farhad, Post-Beittenmiller, Dusty, Weiss, James D., Valentin, Henry E.
• Format: Journal Article
• Language: English
• Published: Belgium Elsevier Inc 01.09.2005
• Subjects: Gene Expression Regulation, Plant - physiology; Genetic Enhancement - methods; Glycine max - genetics; Glycine max - metabolism; Nutrition; Oilseed crop; Seeds - genetics; Seeds - metabolism; Soybean Oil - chemistry; Soybean Oil - metabolism; Tocochromanol; Tocopherol; Tocopherols - chemistry; Tocopherols - metabolism; Tocotrienol; Vitamin E; Tocochromanol; Tocotrienol; Nutrition; Tocopherol; Vitamin E; Oilseed crop
• ISSN: 1096-7176; 1096-7184
• DOI: 10.1016/j.ymben.2005.05.005

Tocochromanols (tocopherols and tocotrienols) are important lipid soluble antioxidants and are an essential part of the mammalian diet. Oilseeds are particularly rich in tocochromanols with an average concentration 10-fold higher than other plant tissues. Here we describe a systematic approach to identify rate-limiting reactions in the tocochromanol biosynthetic pathway, and the application of this knowledge to engineer tocochromanol biosynthesis in oilseed crops. Seed-specific expression of genes encoding limiting tocochromanol pathway enzymes in soybean increased total tocochromanols up to 15-fold from 320 ng/mg in WT seed to 4800 ng/mg in seed from the best performing event. Although WT soybean seed contain only traces of tocotrienols, these transgenic soybean accumulated up to 94% of their tocochromanols as tocotrienols. Upon crossing transgenic high tocochromanol soybean with transgenic high α-tocopherol soybean, the vitamin E activity in the best performing F2-seed was calculated to be 11-fold higher than the average WT soybean seed vitamin E activity.