title: Characterization of the wound-induced material in Citrus paradisi fruit peel by carbon-13 CP-MAS solid state NMR spectroscopy.
abstract: Grapefruit, Citrus paradisi, were injured, inoculated with Penicillium digitatum and incubated under conditions favourable for the accumulation of defence related material. Histochemical examination revealed that tissues adjacent to inoculated injuries contained phloroglucinol-HCl (PG-HCl) reactive material. Solvent washed cell wall preparations of intact and injured-inoculated peel were further purified using a mixture of cell wall degrading enzymes. Samples from injured inoculated tissue contained PG-HCl reactive globular material in addition to the fragments of xylem and cuticle found in controls. The principal chemical moieties of the material that accumulates in grapefruit injuries during wound-healing were studied by solid state 13C cross-polarization magic angle spinning NMR. A complete assignment of the NMR signals was made. From the analysis evidence was found that cellulose and hemicellulose are the biopolymers present in the intact peel samples, in addition, relevant quantities of cutin were found in the residues of enzyme digest. The NMR difference spectrum intact- wounded peels showed resonances which were attributed to all major functional groups of the aromatic-aliphatic suberin polyester of new material produced by the wounds. Information on the latter polyester was obtained by analyzing the T(1)rho (1H) relaxation.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Cagliari, Complesso Universitario di Monserrato, Strada Statale 554, Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Lai
authors.forename: Adolfo
authors.initials: A
authors.lastname: Lai
authors.forename: Richard R
authors.initials: RR
authors.lastname: Stange
authors.forename: T Greg
authors.initials: TG
authors.lastname: McCollum
authors.forename: Mario
authors.initials: M
authors.lastname: Schirra
mesh_terms: D002247:Carbon Isotopes; D002482:Cellulose / Q000032:analysis / Q000378:metabolism; D002855:Chromatography, Thin Layer; D032083:Citrus paradisi / Q000737:chemistry* / Q000378:metabolism; D005638:Fruit / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000032:analysis / Q000378:metabolism; D006651:Histocytochemistry / Q000379:methods; D008055:Lipids; D008563:Membrane Lipids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010407:Penicillium / Q000737:chemistry; D010696:Phloroglucinol / Q000737:chemistry* / Q000378:metabolism; D018521:Plant Physiological Phenomena; D013314:Stress, Mechanical
chemical_list: D002247:Carbon Isotopes; D008055:Lipids; D008563:Membrane Lipids; C000521:cutin; C065875:suberin; D002482:Cellulose; D010696:Phloroglucinol; D006026:Glycoside Hydrolases; C023305:hemicellulase