title: Elucidation of the beta-carotene hydroxylation pathway in Arabidopsis thaliana.
abstract: The first dedicated step in plant xanthophyll biosynthesis is carotenoid hydroxylation. In Arabidopsis thaliana, this reaction is performed by both heme (LUT1 and LUT5) and non-heme (CHY1 and CHY2) hydroxylases. No mutant completely abolishing alpha- or beta-carotene hydroxylation has been described to date. We constructed double and triple mutant combinations in CHY1, CHY2, LUT1, LUT5 and LUT2 (lycopene epsilon-cyclase). In chy1chy2lut2, 80% of leaf carotenoids is represented by beta-carotene. In chy1chy2lut5, beta-carotene hydroxylation is completely abolished, while hydroxylation of the beta-ring of alpha-carotene is still observed. The data are consistent with a role of LUT5 in beta-ring hydroxylation, and with the existence of an additional hydroxylase, acting on the beta-ring of alpha-, but not beta-carotene.
authors.affiliation: Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), Dipartimento Biotecnologie, Centro Ricerche Casaccia, C.P. 2400, Roma 00100, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Fiore
authors.forename: Luca
authors.initials: L
authors.lastname: Dall'osto
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Roberto
authors.initials: R
authors.lastname: Bassi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Giuliano
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D017343:Genes, Plant; D006900:Hydroxylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019207:beta Carotene / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D019207:beta Carotene