Genetic Discrimination of Catharanthus roseus Cultivars by Pyrolysis Mass Spectrometry

Pyrolysis mass spectrometry (PyMS) is a rapid, simple, high-resolution analytical method based on thermal degradation of complex materials in a vacuum. It is widely applied to the discrimination of closely related microbial strains. Leaf samples from eight cultivars (‘Apricot Delight’, ‘Cooler Grape’, ‘Cooler Peppermint’, ‘Equator Grape’, ‘Equator Rose’, ‘Equator White’, ‘Equator White Eye’, and ‘Little Bright Eye’) of Catharanthus roseus were subjected to PyMS for spectral fingerprinting. Discriminant analysis (DA) of PyMS data enabled us to assign these cultivars to discrete clusters. A hierarchical dendrogram based on DA provided a possible relationship among them that was in general agreement with a previously reported classification of the cultivars based on DNA fingerprints. Furthermore, those belonging to the same ‘series’ were grouped into a single cluster, which previously could not be achieved through similar approaches based on Fourier transform infrared spectroscopy or ¹H NMR data. Overall results suggest that chemical differences (i.e., in pyrolysate composition) among cultivars, as detected by mass spectrometry, reflect their genetic variation.