title: Composition and (in)homogeneity of carotenoid crystals in carrot cells revealed by high resolution Raman imaging.
abstract: Three categories of roots differing in both β/α-carotene ratio and in total carotenoid content were selected based on HPLC measurements: high α- and β-carotene (HαHβ), low α- and high β-carotene (LαHβ), and low α- and low β-carotene (LαLβ). Single carotenoid crystals present in the root cells were directly measured using high resolution Raman imaging technique with 532nm and 488nm lasers without compound extraction. Crystals of the HαHβ root had complex composition and consisted of β-carotene accompanied by α-carotene. In the LαHβ and LαLβ roots, measurements using 532nm laser indicated the presence of β-carotene only, but measurements using 488nm laser confirmed co-occurrence of xanthophylls, presumably lutein. Thus the results show that independently on carotenoid composition in the root, carotenoid crystals are composed of more than one compound. Individual spectra extracted from Raman maps every 0.2-1.0μm had similar shapes in the 1500-1550cm(-1) region indicating that different carotenoid molecules were homogeneously distributed in the whole crystal volume. Additionally, amorphous carotenoids were identified and determined as composed of β-carotene molecules but they had a shifted the ν1 band probably due to the effect of bonding of other plant constituents like proteins or lipids.
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Roman
authors.affiliation: Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, Bobrzynskiego 14, 30-348 Krakow, Poland.
authors.forename: Katarzyna M
authors.initials: KM
authors.lastname: Marzec
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Agriculture in Krakow, Al. 29 Listopada 54, 31-425 Krakow, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Grzebelus
authors.affiliation: USDA-ARS Vegetable Research Crops Unit and Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive, Madison, WI 53706, USA.
authors.forename: Philipp W
authors.initials: PW
authors.lastname: Simon
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland; Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, Bobrzynskiego 14, 30-348 Krakow, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Baranska
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Agriculture in Krakow, Al. 29 Listopada 54, 31-425 Krakow, Poland. Electronic address: baranski@ogr.ur.krakow.pl.
authors.forename: Rafal
authors.initials: R
authors.lastname: Baranski
mesh_terms: D002338:Carotenoids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D003460:Crystallization; D018552:Daucus carota / Q000737:chemistry*; D053758:Nanoparticles / Q000032:analysis*; D059828:Plant Cells / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D002338:Carotenoids
keywords: Daucus carota; Lutein; Raman mapping; Xanthophyll; α-Carotene; β-Carotene