Determination of pathogen-related enzyme action by mass spectrometry analysis of pectin breakdown products of plant cell walls.

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.