Identification of birch pollen species using FTIR spectroscopy

Abstract

In this study, the morphology and chemical composition of pollen grains of six birch species (Betula utilis Doorenbos, B. dahurica, B. maximowicziana, B. pendula, B. pubescens and B. humilis) were examined to verify which of these features allow distinguishing them in a more unambiguous way. For this purpose, scanning electron microscopy and light microscopy, as well as Fourier transform infrared (FTIR) spectroscopy and curve-fitting analysis of amide I profile, were performed. The microscopy images show that the pollen grains of B. pubescens, B. pendula and B. humilis are similar in diameter and significantly smaller than those of others species, with the largest diameter observed for B. utilis Doorenbos. However, the results obtained from FTIR spectroscopy indicate that the chemical compositions of B. pubescens and B. pendula are similar, but B. humilis is outlaying. Summarizing, it is not possible to unambiguously state, which feature or which technique is the best for differentiating between the six chosen birch species. However, the study showed that both techniques have potential for identification of birch pollen species.

Chemotaxonomy of domesticated grasses: a pathway to understanding the origins of agriculture

“…Poaceae pollen grains are all morphologically simple, being more or less spherical with a single, annulate pore and a scabrate to areolate surface sculpture (Köhler and Lange, 1979;Mander et al, 2013). Attempts to distinguish among and between wild grasses and their domesticated relatives have relied on a combination of grain size and shape, pore diameter and position, annulus width and thickness, and exine structure and microsculpture (Andersen, 1979;Beug, 1961Beug, , 2004Bottema, 1992;Dickson, 1988;Firbas, 1937;Joly et al, 2007;Köhler and Lange, 1979;Rowley, 1960;Tweddle et al, 2005), although of these various characters grain size has been most commonly relied upon in routine palynological studies (Bottema, 1992). Pollen grain size varies between 30 and 100 µm among Poaceae species and broadly correlates with genome size (Bennett, 1972).…”

“…Variations in pollen grain surface sculpture have been used as a basis for dividing grains up into broad types, such as the Hordeum type, Triticum type, Avena type and Setaria type of Köhler and Lange (1979). Additional information on grain morphology has then been used to separate out individual taxa, such as Secale cereale L. (rye) being distinguished from other members of the Hordeum type by grain shape and pore position (Dickson, 1988;Köhler and Lange, 1979). These sculpturing types are, however, not phylogenetically or taxonomically meaningful and occur across the grass phylogeny (Mander and Punyasena, 2016).…”

Worthwhile Relevance of Infrared Spectroscopy in Characterization of Samples and Concept of Infrared Spectroscopy-Based Synchrotron Radiation

“…Infrared (IR) microspectroscopy, as implied in the name, is a combination of vibrational mid-infrared (IR) spectroscopy and microscopy [23,[122][123][124]. It enables chemical composition of materials to be determined at microscopic level [125,126]. In general, an IR transmission microscope, with all reflecting optics is attached to a Fourier Transform IR (FTIR) spectrometer, allowing mid-IR absorption spectra to be collected from measurements as small as 5-10 µ min, a sample to be analyzed [127].…”

Combining Chemical Information From Grass Pollen in Multimodal Characterization

“…Vibrational spectroscopic methods, such as FTIR (Pappas et al, 2003;Gottardini et al, 2007;Dell'Anna et al, 2009;Julier et al, 2016;Depciuch et al, 2018;Jardine et al, 2019), Raman scattering (Ivleva et al, 2005;Schulte et al, 2008), and surface enhanced Raman scattering (SERS) (Sengupta et al, 2005;Seifert et al, 2016), as well as mass spectrometric methods (Krause et al, 2012;Lauer et al, 2018) can be applied to classify pollen according to taxonomic relationships based on molecular composition. Pollen spectra can also indicate changes in chemical composition according to genetic background and environmental influences (Zimmermann and Kohler, 2014;Zimmermann et al, 2017;Diehn et al, 2018).…”