Table 3. Overexpression Strategies Reported for Successful Enhancement of α-Tocopherol Content in Plants.
| overexpressed enzyme(s) | species (source of transgene)a | fold increase in α-tocopherol compared with wild type [final content (units) or activity in α-tocopherol equivalents (α-TE)]b |
|---|---|---|
| HPPD (PDS1) | Arabidopsis leaves (At)81 | 1.44 [18 pmol mg–1 (FW)] |
| Arabidopsis leaves (Mi)82 | 2.58 [31 μg g–1 (FW)] | |
| tomato leaves (Mi)82 | 2.67 [11.5 μg g–1 (FW)] | |
| tomato fruits (Mi)82 | 5.0 [10.3 μg g–1 (FW)] | |
| potato leaves (At)83 | 2.12 [15.68 μg g–1 (FW)] | |
| potato tubers (At)83 | 3.66 [1030.7 ng g–1 (FW)] | |
| lettuce leaves (Ls)84 | 4.0 [25.6 μg g–1 (FW)] | |
| Brassica napus (Sy)85 | 1.5 [252 mg kg–1 oil) | |
| HPT (VTE2) | tomato leaves (Md)86 | 3.6 (36.83 μg/g FW) |
| tomato fruits (Md)86 | 1.7 (4.57 μg/g FW) | |
| potato tubers (At)83 | 2.0 [578.6 ng g–1 (FW)] | |
| tobacco leaves (At)87 | 5.4 [12.09 μg g–1 (FW)] | |
| Arabidopsis seeds (At)88 | 1.33 (5.2 mg α-TE 100 g–1 tissue) | |
| tomato mature leaves (Sy)89 | 2.5 [500 ng mg–1 (DW)] | |
| MPBQ (VTE3) | soybean (At)90 | 2.5 [75 ng mg–1 (seed)] |
| TC (VTE1) | lettuce leaves (At)91 | 2.24 [4.7 μg g–1 (FW)] |
| tobacco leaves (At)87 | 4.0 [8.96 μg g–1 (FW)] | |
| γ-TMT (VTE4) | soybean (At)90 | 8.0 [240 ng mg–1 (seed)] |
| Arabidopsis seed (At)92 | 93.4 [342 ng mg–1 (seed)] | |
| Arabidopsis seeds (At)88 | 9.1 (35.6 mg α-TE 100 g–1 tissue) | |
| soybean seed (Pf)93 | 10.4 (450.1 pmol mg–1 tissue) | |
| soybean seed (Bn)94 | 11.1 [340 μg g–1 (DW)] | |
| Brassica juncea seeds (At)95 | 6.6 [367 ng mg–1 (seed)] | |
| lettuce leaves (At)96 | 3.1 [0.37 mg g–1 (DW)] | |
| Perilla frutescens leaves (At)97 | 1.8 (87.8 μg g–1 tissue) | |
| Perilla frutescens seeds (Pf)98 | 22.5 [1.31 mg g–1 (seed)] | |
| tobacco seeds (At)23 | 9.6 [120 μg g–1 (FW)] | |
| VTE2+VTE1 | tobacco leaves (At+At)87 | 7.1 [15.90 μg g–1 (FW)] |
| VTE3+VTE4 | soybean (At+At)90 | 9.1 [273 ng mg–1 (seed)] |
| VTE2+VTE4 | Arabidopsis seeds (At+At)88 | 12.0 (47.4 mg α-TE 100 g–1 tissue) |
| VTE1+VTE4 | tobacco leaves (At+At)79 | 1.2 [14.8 μg g–1 (FW)] |
| VTE2+VTE1+VTE4 | tomato mature leaves (Sy+Sy+At)89 | 4.0 [900 ng mg–1 (DW)] |
a
At, Arabidopsis thaliana; Mi, Mangifera indica; Ls, Lactus sativa; Sy, Synechocystis; Pf, Perilla frutescens; Bn, Brassica napus.
b
FW, fresh weight; DW, dry weight.