METABOLIC ENGINEERING OF α-TOCOTRIENOL THROUGH PTGS MECHANISMS AND ISOPRENOID/NON-MEVALONATE PATHWAYS IN PERENNIAL CROPS
UMAIYAL MUNUSAMY
Centre for Research in Biotechnology for Agriculture (CEBAR), Level 3, Research Management & Innovation Complex, University of Malaya, 50603 Kuala Lumpur, Malaysia and Department of Agriculture Technology, Faculty of Agriculture, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
SITI NOR AKMAR ABDULLAH *
Department of Agriculture Technology, Faculty of Agriculture, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia and Laboratory of Plantation Crops, Institute of Tropical Agriculture, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
MAHERAN ABD AZIZ
Department of Agriculture Technology, Faculty of Agriculture, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia and Laboratory of Plantation Crops, Institute of Tropical Agriculture, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
HUZWAH KHAZA`AI
Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
*Author to whom correspondence should be addressed.
Abstract
α-tocotrienol provides effective neuro and cellular protection against oxidative stress and aging among vitamin E analogs. Therefore, consuming it through natural food resources become popular as concern is rising on the safety of ingesting it as a clinical supplement. The content of α-tocotrienol varies among plant species and various parts of the plant. Boosting the level of α-tocotrienol in perennial crops are an attractive way to consume. Therefore, perennial crops that are lacking in α-tocotrienol were identified. In this study, amaranth and leek was transiently transformed to produce α-tocotrienol through post transcriptional mechanisms (PTGS) and targeted metabolic engineering of isoprenoid and non-mevalonate pathway. We observed only α-tocopherol suppression in amaranth and leek leaves in plant infiltrated with p5b5 while α-tocopherol suppression followed by α-tocotrienol synthesis in plant infiltrated with p5d9. Our results revealed that shift in the pathway from isoprenoid to non mevalonate to produce α-tocotrienol occur once reduction in α-tocopherol at a maximum level was achieved. Hence, suggest that variations of α-tocochromanols composition can be manipulated by triggering post transcriptional mechanisms (PTGS) which leads to targeted metabolic engineering of isoprenoid and non-mevalonate pathway.
Keywords: Perennial crops, co-suppression, homogentisate phytyltransferase, α-tocochromanols, constitutive promoter, vitamin E biosynthetic pathway