title: Plastochromanol-8 and tocopherols are essential lipid-soluble antioxidants during seed desiccation and quiescence in Arabidopsis.
abstract: Given their essential role as vitamin E, tocopherols and tocotrienols have been studied extensively in animals and plants. In contrast, our understanding of the function of plastochromanol-8 (PC-8), a third type of tocochromanol with a longer side chain, is very limited despite the wide distribution of PC-8 in the plant kingdom, including species consumed by humans. To investigate PC-8 function in vivo, we combined the Arabidopsis vte1 mutation that eliminates tocopherols and PC-8 and causes the accumulation of 2,3-dimethyl-6-phytyl-1,4-benzoquinol (DMPBQ), a redox-active tocopherol precursor, and the vte2 mutation that eliminates tocopherols without affecting PC-8. The vte2 vte1 double mutant lacks tocopherols, PC-8, and DMPBQ, and exhibits the most severe physiological and biochemical phenotypes of any tocochromanol-affected genotype isolated to date, most notably a severe seedling developmental phenotype associated with massive lipid oxidation initiated during seed desiccation and amplified during seed quiescence. In contrast, the presence of PC-8 in vte2 suppresses or attenuates all of the developmental and biochemical phenotypes observed in vte2 vte1, demonstrating that PC-8 is a lipid antioxidant in vivo. Finally, the low relative fitness of vte2 vte1 demonstrates that tocopherols and PC-8 are in vivo lipid antioxidants essential for seed plant survival.
authors.affiliation: Department of Biochemistry and Molecular Biology and Chemistry, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Laurent
authors.initials: L
authors.lastname: Mène-Saffrané
authors.forename: A Daniel
authors.initials: AD
authors.lastname: Jones
authors.forename: Dean
authors.initials: D
authors.lastname: DellaPenna
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000235:genetics; D002839:Chromans / Q000378:metabolism*; D002849:Chromatography, Gas; D017931:DNA Primers / Q000235:genetics; D005838:Genotype; D019751:Intramolecular Transferases / Q000235:genetics; D050356:Lipid Metabolism; D013058:Mass Spectrometry; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D012639:Seeds / Q000737:chemistry* / Q000254:growth & development; D024505:Tocopherols / Q000378:metabolism*; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D002839:Chromans; D017931:DNA Primers; D014810:Vitamin E; C013649:plastochromanol 8; D019883:Alkyl and Aryl Transferases; C446531:HPT1 protein, Arabidopsis; D019751:Intramolecular Transferases; C103397:tocopherol cyclase; D024505:Tocopherols