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WRINKLED 1 and ACYL‐COA:DIACYLGLYCEROL ACYLTRANSFERASE 1 regulate tocochromanol metabolism in Arabidopsis
Author(s) -
Pellaud Sébastien,
Bory Alexandre,
Chabert Valentin,
Romanens Joëlle,
ChaisseLeal Laurie,
Doan Anh Vu,
Frey Lucas,
Gust Andrea,
Fromm Katharina M.,
MèneSaffrané Laurent
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14856
Subject(s) - arabidopsis , diacylglycerol kinase , biochemistry , mutant , biology , biosynthesis , gene , tocopherol , acyltransferase , chemistry , vitamin e , enzyme , antioxidant , protein kinase c
Summary Photosynthetic organisms such as plants, algae and some cyanobacteria synthesize tocochromanols, a group of compounds that encompasses tocopherols and tocotrienols and that exhibits vitamin E activity in animals. While most vitamin E biosynthetic genes have been identified in plant genomes, regulatory genes controlling tocopherol accumulation are currently unknown. We isolated by forward genetics Arabidopsis enhanced vitamin E ( eve ) mutants that overaccumulate the classic tocopherols and plastochromanol‐8, and a tocochromanol unknown in this species. We mapped eve1 and eve4 , and identified the unknown Arabidopsis tocochromanol by using a combination of analytical tools. In addition, we determined its biosynthetic pathway with a series of tocochromanol biosynthetic mutants and transgenic lines. eve1 and eve4 are two seed lipid mutants affecting the WRINKLED 1 ( WRI1 ) and ACYL‐COA:DIACYLGLYCEROLACYLTRANSFERASE 1 ( DGAT1 ) genes, respectively. The unknown tocochromanol is 11′‐12′ γ‐tocomonoenol, whose biosynthesis is VITAMIN E 1 ( VTE 1) ‐ and VTE 2‐dependent and is initiated by the condensation of homogentisate ( HGA ) and tetrahydrogeranylgeranyl pyrophosphate. This study identifies the first two regulatory genes, WRI 1 and DGAT 1 , that control the synthesis of all tocochromanol forms in seeds, and shows the existence of a metabolic trade‐off between lipid and tocochromanol metabolisms. Moreover, it shows that Arabidopsis possesses a tocomonoenol biosynthetic pathway that competes with tocopherol synthesis.