Taxonomic relationships of pollens from matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry data using multivariate statistics

Abstract

Our results indicate that the chemical information represented by MALDI-TOFMS data is useful for reconstructing taxonomic relationships and is complementary to other chemical information on pollen from other spectroscopic data.

Simplifying the Preparation of Pollen Grains for MALDI-TOF MS Classification

“…In accord with this, the Corylus -typical spectral regions, e.g., from m / z 5400 to 6117 [15], yielded positive signals in the loadings of the respective first PCs (see Figure 3, 2nd and 4th column, black loadings spectra). The other species, however, cannot be differentiated clearly from each other using the scores plots in Figure 2d,e,j–l.…”

“…In Figure 2a, the scores of Corylus avellana spectra feature negative values for the first and second PCs, which result in negative Corylus- typical peaks [15] in the respective loadings (e.g., at m / z 3098, m / z 4103 and the range from m / z 5400 to 6110 shown in Figure 3a, top black spectra and middle gray spectra). Alnus cordata spectra provide scores values that are positive for the first PC and negative for the second PC (Figure 2a).…”

“…Alnus cordata spectra provide scores values that are positive for the first PC and negative for the second PC (Figure 2a). The corresponding loadings (Figure 3a) showed peaks in the lower mass range of m / z 1310 to 1463 and peaks around m / z 5204 and m / z 9488 that can be assigned to Alnus [15]. The Pinus sylvestris spectra were characterized by scores values close to zero for the first PC and very positive score values for the second PC.…”

“…For pollen classification and identification, the applicability of MALDI-TOF MS was proven, combining the mass spectral data with hierarchical cluster analysis (HCA) and principal component analysis (PCA) [15]. There, almost 200 pollen samples of 74 different species from 11 genera and 2 plant orders were classified according to their taxonomic relationships, including discrimination of species that feature a very high chemical similarity [15].…”

“…There, almost 200 pollen samples of 74 different species from 11 genera and 2 plant orders were classified according to their taxonomic relationships, including discrimination of species that feature a very high chemical similarity [15]. The application of multivariate statistics (e.g., PCA) to mass spectral patterns yields an enormous improvement concerning taxonomic classification of the samples compared to common microscopic techniques.…”