Product Code Database
Sporopollenin is a biological polymer found as a major component of the tough outer (exine) walls of plant and pollen grains. It is chemically very stable and has been described as the "toughest material in the plant kingdom". It is well preserved in and and with it surviving in spores from the mid‐Ordovician (475 million years ago) providing the earliest evidence of Plant on land.
The exine layer is often intricately sculptured in species-specific patterns, allowing material recovered from (for example) lake sediments to provide useful information to palynology about past plant and fungal populations. Sporopollenin has found uses in the field of paleoclimatology as well as a marker of past ultraviolet (UVB) levels in the sunlight. Sporopollenin is also found in the cell walls of several taxa of green alga, including Phycopeltis (an ) and Chlorella.
are dispersed by many different environmental factors, such as wind, water or animals. In suitable conditions, the sporopollenin-rich walls of pollen grains and spores can persist in the fossil record for hundreds of millions of years, since sporopollenin is resistant to chemical degradation by organic and inorganic chemicals.
In 2019, thioacidolysis degradation and solid-state NMR was used to determine the molecular structure of Pinus rigida sporopollenin, finding it primarily composed of polyvinyl alcohol units alongside other aliphatic , all crosslinked through a series of acetal linkages. Its complex and heterogeneous chemical structure gives some protection from the biodegradative enzymes of bacteria, Fungus and animals. Some aromatic structures based on p-Coumaric acid and naringenin were also identified within the sporopollenin polymer. These can absorb ultraviolet (UV) light, preventing it from penetrating further into the spore. This is relevant to the role of pollen and spores in transporting and dispersing of plants. The DNA of the gametes is readily damaged by the ultraviolet component of daylight. Sporopollenin thus provides some protection from these damages as well as a physically robust container.
Analyses of sporopollenin from the Lycopodiaceae Lycopodium in the late 1980s have shown distinct structural differences from that of flowering plants. In 2020, more detailed analysis of sporopollenin from Lycopodium clavatum provided more structural information. It showed a complete lack of aromatic structures and the presence of a Macrocycle backbone of polyHydroxylation tetraketide-like monomers with pseudo-aromatic 2-pyrone rings. These were crosslinked to a poly(hydroxy acid) chain by ether linkages to form the polymer.
|
|
