Grapevine untargeted metabolomics to uncover potential biomarkers of fungal/oomycetes-associated diseases

The leaf metabolome from eleven field grown Vitis genotypes (5 Vitis species and 6 Vitis vinifera) was analysed by Fourier Transform Ion Cyclotron Resonance mass spectrometry (FT-ICR-MS). For the analysis, samples were diluted 1000-fold in methanol and human leucine enkephalin (Sigma Aldrich) was added for internal calibration of each mass spectrum ([M+H]+ =556.276575 Da or [M-H]- = 554.262022 Da). Samples were analysed by direct infusion on an Apex Qe 7-Tesla FT-ICR-MS (Brüker Daltonics). Spectra were acquired with an accumulation of 250 scans for each spectrum, at both positive (ESI+) and negative (ESI-) electrospray ionization modes, in the mass range of 100 to 1000 Th. Data Analysis 5.0 (Brüker Daltonics, Bremen, Germany) was used to internally calibrate each mass spectrum using leucine enkephalin for single point calibration. Peaks lists (m/z and intensity) were retrieved, considering a minimum signal-to-noise ratio of 4.