title: Identification of Plastoglobules as a Site of Carotenoid Cleavage.
abstract: Carotenoids play an essential role in light harvesting and protection from excess light. During chloroplast senescence carotenoids are released from their binding proteins and are eventually metabolized. Carotenoid cleavage dioxygenase 4 (CCD4) is involved in carotenoid breakdown in senescing leaf and desiccating seed, and is part of the proteome of plastoglobules (PG), which are thylakoid-associated lipid droplets. Here, we demonstrate that CCD4 is functionally active in PG. Leaves ofArabidopsis thaliana ccd4mutants constitutively expressing CCD4 fused to yellow fluorescent protein showed strong fluorescence in PG and reduced carotenoid levels upon dark-induced senescence. Lipidome-wide analysis indicated that β-carotene, lutein, and violaxanthin were the principle substrates of CCD4in vivoand were cleaved in senescing chloroplasts. Moreover, carotenoids were shown to accumulate in PG ofccd4mutant plants during senescence, indicating translocation of carotenoids to PG prior to degradation.
authors.affiliation: Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Rottet
authors.affiliation: Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Julie
authors.initials: J
authors.lastname: Devillers
authors.affiliation: Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Gaétan
authors.initials: G
authors.lastname: Glauser
authors.affiliation: Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Véronique
authors.initials: V
authors.lastname: Douet
authors.affiliation: Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Céline
authors.initials: C
authors.lastname: Besagni
authors.affiliation: Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel Neuchâtel, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Kessler
keywords: Arabidopsis thaliana; carotenoid; ccd4; chloroplast; plastoglobule; senescence