Pollen and spores are the reproductive structures (microorganisms) of plants and fungi, and thus have key function during plant and fungal life cycles. Identification of pollen and spores provides useful information in various fields, for instance in public health for allergy forecasts, in ecology for monitoring of life cycles of vegetation and mycobiota, and in forensics for temporal and spatial determination of a criminal event. Unfortunately, current studies are still confined to visual measurements of pollen and spore morphologies under a microscope and the research has remained basically unchanged over the last hundred years. The identification requires laborious visual recognition of bioparticles by a skilled microscopist with specific knowledge of pollen and spore morphology.

Male cones with pollen of Mediterranean cypress (left) and Greek fir (right). The corresponding FTIR spectra of pollen (middle); the marked vibrational bands are associated with lipids (L), proteins (P), sporopollenins (S) and carbohydrates (C).
Recently, infrared (FTIR) and Raman spectroscopies have attracted attention as methods for characterisation of plants and fungi. As opposed to morphological characterisation with microscopy, these two vibrational spectroscopy techniques offer an operator-independent approach based on chemical characterisation via identifiable spectral features. Roughly, a spectrum of a microorganism contains specific signatures of the constituent biomolecules, such as lipids, proteins, carbohydrates, pigments and grain wall biopolymers (sporopollenins, cellulose, glucan and chitin). These chemicals are the principal structural and nutritious components of microorganisms, and they are responsible for the majority of phenotypic attributes. Since the corresponding spectral signals of these chemicals are highly specific, vibrational spectroscopy is an excellent tool for biochemical analysis of plants and fungi.
Projects:
Quantitative estimates of past UV-B irradiance from fossil pollen
Research Council of Norway (FRIMEDBIO, project Nº. 324670)
Selectivity of FTIR microspectra from single grass pollen grains for species identification
Helmholtz Zentrum Berlin (HZB projects Nº. 18207701 and 19107969)
Pollen Chemistry as the Next Generation Tool in Palaeoecological Research – Theory, Methods and Applications
Research Council of Norway (FRIMEDBIO, project Nº. 249844)
Plant Phenotyping by Vibrational Spectroscopy of Pollen
European Commission, Research Executive Agency (FP7-PEOPLE-2012-IEF, project Nº. 328289)
Phenotyping of flora of Svalbard by vibrational spectroscopy of pollen and seeds
Svalbard Science Forum (AFG project Nº. 246125, RiS 10113)
Combined FTIR and Raman analysis of pollen composition for studying plant adaptation to environmental changes
Research Council of Norway (DAADppp mobility grants, project Nº. 233941)
Synchrotron infrared microspectroscopy of pollen grains
SOLEIL, French national synchrotron facility (SOLEIL, project Nº. 20120345)
Literature:
Heitmann Solheim J., Borondics F., Zimmermann B., Sandt C., Muthreich F., Kohler A.
An automated approach for fringe frequency estimation and removal in infrared spectroscopy and hyperspectral imaging of biological samples
Journal of Biophotonics (2021)
Diehn S., Zimmermann B., Tafintseva V., Bağcıoğlu M., Kohler A., Ohlson M., Fjellheim S., Kneipp J.
Discrimination of grass pollen of different species by FTIR spectroscopy of individual pollen grains
Analytical and Bioanalytical Chemistry 412 (2020) 6459-6474
Diehn S., Zimmermann S., Tafintseva V., Seifert S., Bagcioglu M., Ohlson M., Weidner S., Fjellheim S., Kohler A., Kneipp J.
Combining chemical information from grass pollen in multimodal characterization
Frontiers in Plant Science 10 (2020) 1788
Muthreich F., Zimmermann B., Birks H.J.B., Vila‐Viçosa C.M., Seddon A.W.R.
Chemical variations in Quercus pollen as a tool for taxonomic identification: Implications for long‐term ecological and biogeographical research
Journal of Biogeography 47 (2020) 1298
Kenđel A., Zimmermann B.
Chemical Analysis of Pollen by FT-Raman and FTIR Spectroscopies.
Frontiers in Plant Science 11 (2020) 352
Seddon A.W.R., Festi D., Robson T.M., Zimmermann B.
Fossil pollen and spores as a tool for reconstructing ancient solar-ultraviolet irradiance received by plants: an assessment of prospects and challenges using proxy-system modelling
Photochemical and Photobiological Sciences 18 (2019) 275
Innes S.N., Arve L.E., Zimmermann B., Nybakken L., Melby T.I., Solhaug K.A., Olsen J.E., Torre S.
Elevated air humidity increases UV mediated leaf and DNA damage in pea (Pisum sativum) due to reduced flavonoid content and antioxidant power
Photochemical and Photobiological Sciences 18 (2019) 387
Diehn S., Zimmermann B., Bağcıoğlu M., Seifert S., Kohler A., Ohlson M., Fjellheim S., Weidner S., Kneipp J.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) shows adaptation of grass pollen composition
Scientific Reports 8 (2018) 16591.
Blümel R., Lukacs R., Zimmermann B., Bağcıoğlu M., Kohler A.
Observation of Mie ripples in the synchrotron FTIR spectra of spheroidal pollen grains
Journal of the Optical Society of America A 35 (2018) 1769
Zimmermann B.
Chemical characterization and identification of Pinaceae pollen by infrared microspectroscopy.
Planta 247 (2018) 171.
Zimmermann B., Bağcıoğlu M., Tafinstseva V., Kohler A., Ohlson M., Fjellheim S.
A high-throughput FTIR spectroscopy approach to assess adaptive variation in pollen quality
Ecology and Evolution 7 (2017) 10839
Bağcıoğlu M., Kohler A., Seifert S., Kneipp J., Zimmermann B.
Monitoring of plant-environment interactions by high throughput FTIR spectroscopy of pollen
Methods in Ecology and Evolution 8 (2017) 870
Zimmermann B., Tafintseva V., Bağcıoğlu M., Høegh Berdahl M., Kohler A.
Analysis of allergenic pollen by FTIR microspectroscopy
Analytical Chemistry 88 (2016) 803
Bağcıoğlu M., Zimmermann B., Kohler A.
A multiscale vibrational spectroscopic approach for identification and biochemical characterization of pollen
PLOS One 10 (2015) e0137899
Zimmermann B., Bağcıoğlu M., Sandt C., Kohler A.
Vibrational microspectroscopy enables chemical characterization of single pollen grains as well as comparative analysis of plant species based on pollen ultrastructure
Planta 242 (2015) 1237
Zimmermann B., Tkalčec Z., Mešić A., Kohler A.
Characterizing aeroallergens by infrared spectroscopy of fungal spores and pollen
PLOS One 10 (2015) e0124240
Lukacs R., Blümel R., Zimmermann B., Bağcıoğlu M., Kohler A.
Recovery of absorbance spectra of micrometer-sized biological and inanimate particles
Analyst 140 (2015) 3273-3284
Zimmermann B., Kohler A.
Infrared spectroscopy of pollen identifies plant species and genus as well as environmental conditions
PLOS One 9 (2014) e95417
Zimmermann B.
Characterization of pollen by vibrational spectroscopy
Applied Spectroscopy 64 (2010) 1364