Induced Production of α-Tocotrienol by Co-Suppression of Tocopherol Cyclase Gene in Vegetable Crops
Umaiyal Munusamy, Siti Nor Akmar Abdullah, Maheran Abdul Aziz, Huzwah Khazaai and Lai Mun Seong
DOI : 10.3844/ajbbsp.2013.355.364
American Journal of Biochemistry and Biotechnology
Volume 9, Issue 4
This study involves the induced production of α-tocotrienol by the co-suppression of tocopherol cyclase gene. The Tocopherol/Tocotrienol Cyclase (TC) is a key enzyme involved in the biosynthesis of α-tocotrienol. The partial conserved cDNA of TC gene isolated from the oil palm (Elaeis guineensis) that shared greater than 75% sequence identity with TC sequences from other plant species was used to silence TC gene expression in Amaranthus sp. and Allium porrum leaves by co-suppression strategies. This was carried out using recombinant vector constructs designated as p4a11 and p4c9 containing TC driven by the maize ubiquitin promoter (Ubi1P) and the oil palm leaf-specific promoter (LHCB), respectively. In the Amaranthus sp. leaves infiltrated with p4a11, the α-tocopherol suppression was 85.0, 71.0 and 74.0% on day three, five and seven, respectively and complete suppression was observed in the leaves infiltrated with p4c9. Whereas, only 11.0, 7.0 and 29.0% suppression was detected in Allium porrum leaves infiltrated with p4a11 and 45.0, 4.0 and 57.0% of suppression was observed in Allium porrum infiltrated with p4c9 on day three, five and seven, respectively. Silencing of TC gene driven by LHCB (p4c9) causes the reduction of α-tocopherol production better than by Ubi1P (p4a11). The results have demonstrated that gene silencing through co-suppression is capable of producing α-tocotrienol. However, there is no correlation between the α-tocotrienol production and the α-tocopherol suppression. It has been suggested that the transgene mediated co-suppression mechanism had triggered the vitamin E biosynthesis metabolic pathway to shift towards producing α-tocotrienol.
© 2013 Umaiyal Munusamy, Siti Nor Akmar Abdullah, Maheran Abdul Aziz, Huzwah Khazaai and Lai Mun Seong. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.