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

• Main Authors: Fraser, Wesley, 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: English
• Published: 2011
• Subjects: Polar Research
• Online Access: https://radar.brookes.ac.uk/radar/items/247c298e-2c6b-4de3-92e0-d7378754b628/1/; https://radar.brookes.ac.uk/radar/file/247c298e-2c6b-4de3-92e0-d7378754b628/1/Fraser+et+al+2011+Polar+Research+30+8312.pdf

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 corresponds 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.