Differentiation of two morphologically similar Amazonian Aniba species by mass spectrometry leaf fingerprinting

Abstract

The wood of the Amazonian tree Aniba rosaeodora Ducke has been intensively exploited since the 1920s and remains a much valued material in the perfume industry, leading to its classification as a plant at risk of extinction. Another Amazonian tree, Aniba parviflora, is morphologically highly similar to the much more valuable A. rosaeodora and is illegally commercialized in the seedling stage as counterfeit samples of the much more valuable A. rosaeodora. A technique that would be able to perform rapid, versatile and reliable differentiation of the two species would therefore be valuable to detect such illegal practice. Herein we describe unequivocal differentiation between the two morphologically similar Amazonian Aniba species by leaf mass spectrometry fingerprinting using a small fragment of the leaf. Two ionization techniques were tested (ESI and V_L-EASI), and mass spectra obtained from many leaves and at different points on the leaf surface belonging to the same species were very similar and reproducible, whereas spectra between the two species were markedly different. Marker ions detected in each spectrum were structurally characterized based on the accurate mass measurements, MS/MS fragmentation patterns and comparison of the results with reported data. Principal component analysis (PCA) was used to validate the differentiation of the spectra. MS leaf fingerprinting using both ESI and V_L-EASI offers therefore a rapid, versatile and reliable method to differentiate morphologically similar plant species, as demonstrated herein for the two Amazonian Aniba species at the seedling stage.