Cloning And Functional Characterizations Of Soybean Vitamin E Biosynthesis Genes

Soybean is a major source of oil and protein in the human diet. It is also a main source of natural vitamin E, that is an important fat-soluble antioxidant. Vitamin E is not only important for animal central nervous system, but also had a vital role in building and maintaining of plant cell membrane. Considering the bove advantages we have focused on metabolic engineering of vitamin E biosynthesis pathway. In this study at different developmental stages the soybean seeds were stressed and specific vitamin E content was measured. The stress responsive genes were identified and cloned to further characterize their function in vitamin E biosynthesis in soybean plants.The Glycine max Gm HPT-1, Gm HPT-2, Gm HPT-3 genes were overexpressed in Arabidopsis lines. Overexpressed lines showed increased levels of vitamin E(20.3%, 11.2%, 38.5%, respectively) relative to wild-type. The Gm MPBQ-1 and Gm MPBQ-2 over expression in Arabidopsis shows increased vitamin E content up to and 6 and 7.3-fold more α- tocopherol level respectively, as compared to wild type while Gm TC-1 and Gm TC-2 overexpressed lines relative to wild-type lines increased vitamin E level to 10.9% and 7.8%, respectively.. The overexpressed Gm TMT-2 and Gm TMT-3 have negati ve impact on Vitamin E level, while α- tocopherol, total tocopherol ratio increased to 42% and 33%, respectively. The variation in the vitamin E level was observed through different developmental stages of soybean seeds. The increased trend were observed in the total contents of vitamin E, γ-δ-tocopherol while α- tocopherol content increased in the early stages and then decreased during late seed developmental stages. In black bean, the vitamin E level increased in early stages while decreases in the lat e stages. The γ-tocopherol content increased in early stages and become constant in the late stages while δ-tocopherol and α- tocopherol follows the same trend as total vitamin E in black beans. The abiotic stresses also alters the vitamin E content in the soybean seeds. The low temperature and processing time increased 3.3 time vitamin E level than control in the first 24 hours of treatment.