UV-B absorbing pigments in spores: biochemical responses to shade in a high-latitude birch forest and implications for sporopollenin-based proxies of past environmental change

• Published in: Polar Research
• Main Authors: Fraser, Wesley T., Sephton, Mark A., Watson, Jonathan S., Self, Stephen, Lomax, Barry H., James, David I., Wellman, Charles H., Callaghan, Terry V., Beerling, David J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2011
• Subjects: Polar Research
• Online Access: https://oro.open.ac.uk/29293/; https://oro.open.ac.uk/29293/1/Fraser_PR_11.pdf; http://www.polarresearch.net/index.php/polar/article/view/8312/pdf_223; https://doi.org/10.3402/polar.v30i0.8312

Current attempts to develop a proxy for Earth’s surface ultraviolet-B (UV-B) flux focus on the organic chemistry of pollen and spores because their constituent biopolymer, sporopollenin, contains UV-B absorbing pigments whose relative abundance may respond to the ambient UV-B flux. Fourier transform infrared (FTIR) microspectroscopy provides a useful tool for rapidly determining the pigment content of spores. In this paper, we use FTIR to detect a chemical response of spore wall UV-B absorbing pigments that correspond with levels of shade beneath the canopy of a high-latitude Swedish birch forest. A 27% reduction in UV-B flux beneath the canopy leads to a significant ( p <0.05) 7.3% reduction in concentration of UV-B absorbing compounds in sporopollenin. The field data from this natural flux gradient in UV-B further support our earlier work on sporopollenin-based proxies derived from sedimentary records and herbaria collections.