Sporopollenin

Sporopollenin is the herbal substance that forms the building material of the Exospors with spores and the exine of pollen grains. Sporopollenin is a highly polymerized heteropolymer of related biomolecules that is constructed of simple aromatic carboxylic acids such as p- coumaric acid ( 4-hydroxy- cinnamic acid ) and long-chain, unbranched aliphatics and aliphatic polyhydroxy components; the cross-linked molecular structure has ether bridges. Sporopollenin is chemically very resistant ( inert to acids, bases, solvents). As a formation mechanism was suspected oxidative polymerization of carotenoids and carotenoid esters. Tracer experiments, however, indicate an involvement of lipid and phenylpropanoid metabolism in the biosynthesis of sporopollenin. The exact chemical composition of a long time was precisely because of the chemical resistance is not known. Because of this characteristic pollen grains are not degraded under exclusion of air and thus become microfossils.

Sporopollenin is a Auflagerung ( Akkruste ) on the cell wall. The function is mainly the protection against UV radiation, but not before dehydration.

Occurrence

Sporopollenin -like substances (eg Algaenane ) occur in some air algae in the group of Chlorophyta: the Trentepohliophyceae and in some Chlorococcales. However, the main deposit is located at the Embryophyten: mosses, fern-like and seed plants. Sporopollenin is considered a key feature of land plants which contributed to the successful colonization of land. The spore (later pollen ) was for resistance thus increases .. sporopollenin is also used in Chara ( Characeae ) in front of whose line of development is considered to be a sister group to Embryophyta.