title: Fibrillin influence on plastid ultrastructure and pigment content in tomato fruit.
abstract: The protein termed fibrillin is involved in the formation of lipoprotein structures, such as plastoglobules and fibrils in certain chromoplast types, which have been implicated in the over-production of pigments due to a sink effect. In order to examine its effect in differentiating chromoplasts of a non-fibrillar type, the pepper fibrillin gene was expressed in tomato fruit. Both the transcript and protein were found to accumulate during tomato fruit ripening from an early mature green stage. However, formation of carotenoid deposition structures in tomato chromoplasts, such as fibrils, was not observed. Nevertheless, a two-fold increase in carotenoid content and associated carotenoid derived flavour volatiles (6-methyl-5-hepten-2-one, geranylacetone, beta-ionone and beta-cyclocitral) was observed. An unexpected phenotypic observation in the transgenic fruit was the delayed loss of thylakoids in differentiating chromoplasts, leading to the transient formation of plastids exhibiting a typical chromoplastic zone adjacent to a protected chloroplastic zone with preserved thylakoids. An in vitro assay has been developed to monitor fibrillin activity on thylakoids: data were obtained suggesting a membrane protection role for fibrillin, more specifically against moderate uncoupling effects.
authors.affiliation: Laboratoire Plastes et Différenciation Cellulaire, Université Joseph Fourier and CNRS (UMR5575), BP 53, F-38041 Grenoble cedex 9, France.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Simkin
authors.forename: Joël
authors.initials: J
authors.lastname: Gaffé
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Alcaraz
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Carde
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bramley
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Marcel
authors.initials: M
authors.lastname: Kuntz
mesh_terms: D002212:Capsicum / Q000235:genetics / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis*; D000071837:Fibrillins; D005638:Fruit / Q000378:metabolism / Q000648:ultrastructure*; D018551:Solanum lycopersicum / Q000235:genetics / Q000648:ultrastructure*; D008840:Microfilament Proteins / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000648:ultrastructure; D018087:Plastids / Q000378:metabolism / Q000648:ultrastructure*; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000071837:Fibrillins; D008840:Microfilament Proteins; D002338:Carotenoids