title: Partial depolymerization of genetically modified potato tuber periderm reveals intermolecular linkages in suberin polyester.
abstract: Suberin is a biopolyester found in specialized plant tissues, both internal and external, with key frontier physiological functions. The information gathered so far from its monomer and oligomer composition, and in situ studies made by solid state techniques, haven't solved the enigma of how the suberin polyester is assembled as a macromolecule. To investigate how monomers are linked in suberin, we analyzed oligomer fragments solubilized by the partial depolymerization of suberin from potato (Solanum tuberosum) tuber periderms. The structure of the suberin oligomers, namely which monomers they included, and the type and frequency of the inter-monomer ester linkages, was assessed by ESI-MS/MS and high resolution NMR analysis. The analyzed potato periderms included the one from wild type (cv. Desirée) and from plants where suberin-biosynthesis genes were downregulated in chain elongation (StKCS6), ω-hydroxylation (CYP86A33) and feruloylation (FHT). Two building blocks were identified as possible key structures in the macromolecular development of the potato periderm suberin: glycerol - α,ω-diacid - glycerol, as the core of a continuous suberin aliphatic polyester; and glycerol - ω-hydroxyacid - ferulic acid, anchoring this polyaliphatic matrix at its periphery to the vicinal polyaromatics, through linking to ferulic acid. The silencing of the StKCS6 gene led to non-significant alterations in suberin structure, showing the relatively minor role of the very-long chain (>C28) fatty acids in potato suberin composition. The silencing of CYP86A33 gene impaired significantly suberin production and disrupted the biosynthesis of acylglycerol structures, proving the relevance of the latter and thus of the glycerol - α,ω-diacid - glycerol unit for the typical suberin lamellar organization. The silencing of the FHT gene led to a lower frequency of ferulate linkages in suberin polyester but to more polyphenolic guaiacyl units as seen by FTIR analyses in the intact polymer.
authors.affiliation: Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal. Electronic address: jograca@isa.ulisboa.pt.
authors.forename: José
authors.initials: J
authors.lastname: Graça
authors.affiliation: Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Cabral
authors.affiliation: Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Sara
authors.initials: S
authors.lastname: Santos
authors.affiliation: ITQB-UNL - Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República-EAN, 2780-157 Oeiras, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Lamosa
authors.affiliation: Laboratori del Suro, Department de Biologia, Universitat de Girona, E-17071 Girona, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Serra
authors.affiliation: Laboratori del Suro, Department de Biologia, Universitat de Girona, E-17071 Girona, Spain.
authors.forename: Marisa
authors.initials: M
authors.lastname: Molinas
authors.affiliation: Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Schreiber
authors.affiliation: Solana Research GmbH, Eichenallee 9, D-24340 Windeby, Germany.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Kauder
authors.affiliation: Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany.
authors.forename: Rochus
authors.initials: R
authors.lastname: Franke
mesh_terms: D003373:Coumaric Acids / Q000737:chemistry; D018506:Gene Expression Regulation, Plant; D005990:Glycerol / Q000737:chemistry; D008055:Lipids / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D035281:Plant Tubers; D030821:Plants, Genetically Modified; D058105:Polymerization; D011198:Solanum tuberosum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D003373:Coumaric Acids; D008055:Lipids; C065875:suberin; C004999:ferulic acid; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C067377:phosphoenolpyruvate-sorbose phosphotransferase; D005990:Glycerol
keywords: Acylglycerols of α,ω-diacids; CYP86A33 ω-hydroxylase; FHT feruloyl transferase; Ferulates of ω-hydroxyacids; Partial depolymerization; Potato periderm; Solanaceae; Solanum tuberosum; StKCS6 fatty acid chain elongase; Suberin