Evolutionary stasis of sporopollenin biochemistry revealed by unaltered Pennsylvanian spores

Abstract

SummaryThe biopolymer sporopollenin present in the spore/pollen walls of all land plants is regarded as one of the most recalcitrant biomacromolecules (biopolymers), providing protection against a range of abiotic stresses. This long-term stability is demonstrated by the near-ubiquitous presence of pollen and spores in the fossil record with spores providing the first evidence for the colonization of the land.Here, we report for the first time chemical analyses of geologically unaltered sporopollenin from Pennsylvanian (c. 310 million yr before present (MyBP)) cave deposits.Our data show that Pennsylvanian Lycophyta megaspore sporopollenin has a strong chemical resemblance to extant relatives and indicates that a co-polymer model of sporopollenin formation is the most likely configuration.Broader comparison indicates that extant sporopollenin structure is similar across widely spaced phylogenetic groups and suggests land plant sporopollenin structure has remained stable since embryophytes invaded land.

Polytrichum commune spores nucleate ice and associated microorganisms increase the temperature of ice nucleation activity onset

“…Similar INA efficiencies for capsule and heated vial spores indicate that heating did not adversely impact any spore coat characteristics that might be responsible for the spore's ability to nucleate ice without microbial associates. This fits with the documented durability of sporopollenin in the spore coat (Fraser et al 2012), which has persisted in the fossil record, making it a useful tool in plant systematics (Hemsley et al 1993).…”

Optical thermal maturity parameters and organic geochemical alteration at low grade diagenesis to anchimetamorphism: A review

“…Recent studies summarized by deLeeuw et al (2006) suggest that the aliphatic moieties are in fact not indigenous to the original sporopollenin and that due to burial and diagenesis the primordial biopolymer is considerably altered even in thermally immature sedimentary rocks. On the contrary,Fraser et al (2012) reported a high chemical similarity of thermally immature Pennsylvanian sporopollenin when compared to extant relatives. They concluded that land plant sporopollenin has remained stable from a chemical point of view since the Palaeozoic.Noteworthy,Watson et al (2007) pointed to another parameter that seems to influence the chemical constitution of sporopollenin.…”

Using the voids to fill the gaps: caves, time, and stratigraphy

“…Although macerated, the plant and animal remains are remarkably well-preserved. The spores preserve original wall structure and sporopollenin Fraser et al 2012), and the scorpion cuticles retain much of the original chitin-protein complex (Cody et al 2011). Aromatic steroids derived from cordaites were also observed (Scott et al 2010).…”