title: Carotenoid gene expression explains the difference of carotenoid accumulation in carrot root tissues.
abstract: Main conclusion Variations in gene expression can partially explain the difference of carotenoid accumulation in secondary phloem and xylem of fleshy carrot roots. The carrot root is well divided into two different tissues separated by vascular cambium: the secondary phloem and xylem. The equilibrium between these two tissues represents an important issue for carrot quality, but the knowledge about the respective carotenoid accumulation is sparse. The aim of this work was (i) to investigate if variation in carotenoid biosynthesis gene expression could explain differences in carotenoid content in phloem and xylem tissues and (ii) to investigate if this regulation is differentially modulated in the respective tissues by water-restricted growing conditions. In this work, five carrot genotypes contrasting by their root color were studied in control and water-restricted conditions. Carotenoid content and the relative expression of 13 genes along the carotenoid biosynthesis pathway were measured in the respective tissues. Results showed that in orange genotypes and the purple one, carotenoid content was higher in phloem compared to xylem. For the red one, no differences were observed. Moreover, in control condition, variations in gene expression explained the different carotenoid accumulations in both tissues, while in water-restricted condition, no clear association between gene expression pattern and variations in carotenoid content could be detected except in orange-rooted genotypes. This work shows that the structural aspect of carrot root is more important for carotenoid accumulation in relation with gene expression levels than the consequences of expression changes upon water restriction.
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Perrin
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Hartmann
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Dubois-Laurent
authors.affiliation: Faculty of Biology II, University of Freiburg, Freiburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Welsch
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Huet
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Latifa
authors.initials: L
authors.lastname: Hamama
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Briard
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Peltier
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Gagné
authors.affiliation: IRHS, Agrocampus Ouest, INRA, SFR QuaSaV, Université d'Angers, 49071, Beaucouzé, France. emmanuel.geoffriau@agrocampus-ouest.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Geoffriau
mesh_terms: D002338:Carotenoids / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D018552:Daucus carota / Q000254:growth & development / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D015151:Immunoblotting; D052585:Phloem / Q000502:physiology; D018517:Plant Roots / Q000737:chemistry / Q000502:physiology*; D052584:Xylem / Q000502:physiology
chemical_list: D002338:Carotenoids
keywords: Daucus carota L.; Phloem; Pigment; Transcriptional regulation; Xylem