Metabolic fingerprinting allows discrimination between Ulmus pumila and U-minor, and between U-minor clones of different susceptibility to Dutch elm disease

Experiments were conducted to test whether Fourier transform-infrared (FT-IR) spcctroscopy, coupled with chemometric methods, call distinguish healthy xylem tissues collected from elms known to differ significantly in their susceptiblility to Ophiostoma novo-ulmi Brasier. Twig samples from resistant Ulms pumila L., susceptible U. minor Mill. and resistant U. minor clones were harvested oil 1 May, 15May, 1 June, 1 July and 1 September 2004, and subjected to FT-IR analysis. The application of principal component analysis to the spectral data, followed by discriminant function analysis, discriminated between the three groups of samples in all harvesting dates. The examination of the DF-loading pints allowed the identification of key regions within the Spectra for the separation between clusters. The chemical assignments of these key regions allowed the following interpretations to be made: (i) U. pumila tissues contained enhanced levels of starch, cellulose and lignin with respect to U. minor tissues and (ii) resistant U. minor tissues contained enhanced levels of starch, cellulose and Pectic polysaccharides With respect to susceptible U. minor tissues. The possible roles of the compositional differences in disease resistance, as well as the potential use of FT-IR spectroscopy and chemometrics as a tool for screening resistant elms are discussed.