title: Determination of pathogen-related enzyme action by mass spectrometry analysis of pectin breakdown products of plant cell walls.
abstract: An analytical approach using matrix-assisted laser desorption/ionization mass spectrometry for the structural characterization and assessment of the degree of polymerization of cell wall pectin-derived oligosaccharides (PDOs) in three regions of Botrytis cinerea-infected tomato fruit tissue is described. The PDOs were isolated from lesion centers (extensively macerated tissue), the area just beyond visible lesion margins, and healthy and intact tissue of an inoculated fruit, sampled at a distance from developing lesions. PDO mixtures were directly analyzed by mass spectrometry without chromatographic separation, after minimum cleanup by membrane drop dialysis. The structures identified implied the action of three different pathogen pectin-modifying enzymes. Modifications such as methyl esterification were identified by determination of exact PDO molecular masses and tandem mass spectrometry via collision-induced dissociation. We have identified four PDO series that were generated through the breakdown of homogalacturonan pectins. The decayed and lesion edge areas had fewer and less diverse PDOs than healthy tissues, possibly due to metabolic by-products of the pathogen. This analytical technique provides a simple and rapid method to characterize the pectin-derived oligosaccharides produced by in vivo digestion during pathogen infection.
authors.affiliation: Department of Chemistry, University of California, Davis, CA 95616, USA.
authors.forename: Hyun Joo
authors.initials: HJ
authors.lastname: An
authors.forename: Susan
authors.initials: S
authors.lastname: Lurie
authors.forename: L Carl
authors.initials: LC
authors.lastname: Greve
authors.forename: Danielle
authors.initials: D
authors.lastname: Rosenquist
authors.forename: Crystal
authors.initials: C
authors.lastname: Kirmiz
authors.forename: John M
authors.initials: JM
authors.lastname: Labavitch
authors.forename: Carlito B
authors.initials: CB
authors.lastname: Lebrilla
mesh_terms: D020171:Botrytis / Q000201:enzymology*; D002473:Cell Wall / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005583:Fourier Analysis; D006603:Hexuronic Acids / Q000032:analysis; D018551:Solanum lycopersicum / Q000166:cytology; D009844:Oligosaccharides / Q000032:analysis / Q000302:isolation & purification; D010368:Pectins / Q000032:analysis / Q000378:metabolism*; D011096:Polygalacturonase / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D006603:Hexuronic Acids; D009844:Oligosaccharides; C007819:galacturonic acid; D010368:Pectins; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C027349:pectin lyase