Figure 7.

Tocopherol levels and composition in stressed wild-type, 35S::HPT1/35S::γ-TMT double overexpressers, and the corresponding transgenic parents. Plants were stressed for 15 d, and individual tocopherols were analyzed by normal phase HPLC. After 15 d of stress, 35S::HPT1 leaves accumulated 2-fold higher total tocopherol levels relative to wild type. The conversion of γ- and δ-tocopherols to α- and β-tocopherols occurred to a much greater extent in 35S::HPT1/35S::γ-TMT than in 35S::HPT1, suggesting that γ-TMT activity limits α- and β-tocopherol synthesis in 35S::HPT1 leaves during abiotic stress. Numbers above the error bars represent total tocopherol levels in each line.