from Wikipedia, the free encyclopedia
Pollen grains with different surfaces from different plants: Lilium auratum with monocolpate pollen grains; the others have tricolpate pollen grains: sunflower ( Helianthus annuus ), morning glory ( Ipomoea purpurea ), Sildalcea malviflora , evening primrose ( Oenothera fruticosa ) and castor bean ( Ricinus communis ).

Sporopollenin is the plant substance that forms the building material of the exospore in spores and the exine of pollen grains . Sporopollenin is a highly polymeric heteropolymer of related biomolecules that is built up from simple aromatic carboxylic acids such as p -umaric 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). An oxidative polymerization of carotenoids and carotenoid esters was assumed to be the origin . But tracer experiments suggest an involvement of lipid - and phenylpropanoid - metabolism in the biosynthesis out of sporopollenin. The exact chemical composition was not known for a long time, precisely because of the chemical resistance. Due to this property, pollen grains are not broken down in the absence of air and thus become microfossils .

Sporopollenin is a deposit (accretion) on the cell wall. The main function is to protect against UV radiation but not against dehydration.


Sporopollenin-like substances (e.g. algaenans ) occur in some air algae in the group of Chlorophyta : the Trentepohliophyceae and in some Chlorococcales . The main occurrence, however, is the Embryophyta : the mosses , fern-like and seed plants . Sporopollenin is considered to be a key feature of land plants that has contributed to the successful colonization of land. The spore (later: pollen) resistance was increased. Sporopollenin is also found in chandelier algae (Characeae), whose line of development is considered to be the sister group of the Embryophyta.


Individual evidence

  1. ^ Paul Kenrick & Peter R. Crane (1997): The origin and early evolution of plants on land. Nature 389, 33-39.
  2. CF Delwiche, LE Graham, N. Thomson (1989): lignin-like compounds and sporopollenin in Coleochaete, plans to algal model for the country. Science 245, 399-401.