Albert_2022_Proc.Natl.Acad.Sci.U.S.A_119_e2113488119

SignificanceTocopherols (vitamin E) are plant-synthesized, lipid-soluble antioxidants whose dietary intake, primarily from seed oils, is essential for human health. Tocopherols contain a phytol-derived hydrophobic tail whose in vivo source has been elusive. The most significant genome-wide association signal for Arabidopsis seed tocopherols identified an uncharacterized, seed-specific esterase (VTE7) localized to the chloroplast envelope, where tocopherol synthesis occurs. VTE7 disruption and overexpression had large impacts on tissue tocopherol contents with metabolic phenotypes consistent with release of prenyl alcohols, including phytol, during chlorophyll synthesis, rather than from the bulk degradation of thylakoid chlorophylls as has long been assumed. Understanding the source of phytol for tocopherols will enable breeding and engineering plants for vitamin E biofortification and enhanced stress resilience.