Increasing vitamin E content of canola (Brassica napus L.) by transferring γ-tmt gene

Vitamin E is one of the lipid soluble vitamins consisting of several isoforms, including tocopherols and tocotrienols amongst which the alpha tocopherol is the most active one. The conversion of γ tocophrol to α tocopherol takes place by the activity of γ-tmt enzyme. Many plants including canola lack the γ-tmt gene to enable them to convert γ tocophrol into α tocopherol. The aim of this study was to transfer γ-tmt gene into canola plants to enable them to produce α tocopherol and increase their vitamin E content. γ-tmt gene was isolated from tomato (Lycopersicum esculentum L.), Memory1 cultivar. Then, it was amplified using PCR, digested by XbaΙ enzyme, cloned into the pBluescriptΙΙ cloning vector and subcloned into E. coli. The gene was then transferred into pBI121 vector and subsequently the vector containing the γ-tmt gene was transferred into Agrobactearium tumefaciens. Two canola cultivars Zafam and Hayola 401 were used. The cotyledons of canola seeds were inoculated by Agrobactearium tumefaciens. Seven putative transformants from each cultivar (Zarfam 2 to 8 and Hayola 2 to 8) were chosen for further investigations. After the emergence of shoots and roots, the seedlings were assayed for the presence of γ-tmt gene, by PCR. Vitamin E content of the transformed plants was assayed by FTIR spectrophotometer. Results showed several fold increases in vitamin E contents of the transgenic plants compared to the control. The increases in α-tocopherol content were 2.61 and 2.71 times in Zarfam 6 and Hayola 8, respectively. This approach could be considered as a useful method for fortifying oil seed crops with vitamin E.