Evolutionary stasis of sporopollenin

Fraser,WT, Scott, AC, Forbes, AES, Glasspol, IJ, Plotnick, RE, Kenig, F & Lomax, BH (2012) Evolutionary stasis of sporopollenin biochemistry revealed by unaltered Pennsylvanian spores. New Phytologist, doi:10.1111/j.1469-8137.2012.04301.x

Exceptionally preserved Lycophyte megaspores obtained from a cave in-fill deposit in Illinois of Pennsylvanian age (c.310 Ma) (Plotnick et al., 2009; Scott et al., 2010) offer the opportunity to investigate the chemical composition of ancient sporopollenin. Using the established analytical technique of Fourier transform infrared (FTIR) spectroscopy the chemical functionality of these megaspores has been determined, with the exciting result that these ancient megaspores exhibit a strong chemical resemblance to their modern-day relatives. From this evidence it can be proposed that sporopollenin chemical configuration has remained similar throughout much of the history of terrestrial plants since embryophytes invaded the land. A key factor that enabled this study, and that sets it apart from previous work on ancient palynomorphs is that these megaspores appear to have been subjected to only very minor diagenesis; diagenetic processes have recently been shown to be capable of changing sporopollenin configuration (Watson et al., 2012). This work demonstrates the potential of cave in-fill deposits as long-term storage of exceptionally preserved palnomorphs and could lead to new opportunities in organo-chemical palynology that previously have been hindered by diagenetic over-prints of chemical signals locked in sporopollenin.

References:

Plotnick, RE, Kenig, F, Scott, AC, Glasspool, IJ, Eble, CF & Lang, W (2009) Palaios 24, 627-637.

Scott, AC, Kenig, F, Plotnick, RE, Glasspool, IJ, Chaloner, WG & Eble, CF (2010) Palaeogeography, Palaeoclimatology, Palaeoecology 291, 72-84.

Watson, JS, Fraser, WT & Sephton, MS (2012) Journal of Analytical and Applied Pyrolysis 95, 138-144.

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