Genetic and biochemical basis for alternative routes of tocotrienol biosynthesis for enhanced vitaminEantioxidant production

• DOI: 10.1111/tpj.12067
• Publication Date: 2012-11-08T14:22:33Z
• Authors: Chunyu Zhang; Rebecca E. Cahoon; Sarah C. Hunter; Ming Chen; Jixiang Han; Edgar B. Cahoon
• Keywords: Tocotrienol

Summary Vitamin E tocotrienol synthesis in monocots requires homogentisate geranylgeranyl transferase ( HGGT ), which catalyzes the condensation of and unsaturated C20 isoprenoid diphosphate GGDP ). By contrast, vitamin tocopherol is mediated by phytyltransferase HPT condenses saturated phytyl PDP An ‐independent pathway for has also been shown to occur de‐regulation synthesis. In this paper, basis its impact on production when combined with are explored. Arabidopsis line was initially developed that accumulates tocotrienols co‐expression hydroxyphenylpyruvate dioxygenase HPPD ) Escherichia coli bi‐functional chorismate mutase/prephenate dehydrogenase (TyrA). When crossed into vte2–1 null mutant, lost, indicating /TyrA‐expressing plants atypical use as a substrate. Consistent this, recombinant preferentially catalyzed vitro precursor benzoquinol only presented high molar ratios : . addition, levels were highest early growth stages /TyrA lines, but decreased strongly relative tocopherols during later known accumulate. Collectively, these results indicate /TyrA‐induced occurs upon enrichment prenyl pools. Finally, expression leaves seeds resulted large additive increases production, concentrations limit ‐catalyzed