Suberine
Suberin is a plant-based, hydrophobic biopolymer that is embedded in cell walls . Suberinized cells are found both in the periderm as a secondary closing tissue and in subterranean plant organs . Suberin is named after the species name of the cork oak ( Quercus suber ).
structure
The suberine can be divided into two different domains: a polyphenolic and a polyaliphatic domain. In the polyaliphatic fraction, dicarboxylic acids , hydroxycarboxylic acids , long chain fatty acids and phenolic acids were found. One component is suberic acid . Current research also provides evidence that glycerol is also a very prominent monomer of the compound. The phenolic part shows a similarity to lignin . However, the proportion of monolignols is significantly below that of lignin.
Regarding the structure, it can be assumed that the two mentioned parts appear spatially separated in the suberine. The well-known suberine lamellae can be observed in the transmission electron microscope (TEM). However, since the suberine can currently only be examined after depolymerization , exact information on the exact structure is still pending. It is only certain that the individual monomers are linked to one another via esterification reactions .
Occurrence
Suberin occurs mainly in the cell walls of the phellem (cork), which is formed by the phellogen (cork cambium) outwards towards the surface of the plant body. It also occurs in the primary endodermis , in which it impregnates the Casparian streak , and in the secondary endodermis, in which it is deposited as a suberin lamella on the inner cell wall. Suberin forms a matrix in which waxes are embedded. In this combination it prevents the loss of water and other molecules to the plant surface.
Biological function
As a hydrophobic material, the suberin in the root acts as a seal against water penetration. The transport of water and matter across this interface is only possible via the symplasts and thus controllable by the plant.
Individual evidence
- ↑ Suberin - Lexicon of Biology . ( Spektrum.de [accessed on April 15, 2017]).
literature
- MA Bernards: Demystifying suberin . In: Canadian Journal of Botany . 80, No. 3, 2002, pp. 227-240. doi : 10.1139 / b02-017 .
- PE Kolattukudy: Biochemistry and function of cutin and suberin . In: Canadian Journal of Botany . 62, No. 12, 1984, pp. 2918-2933. doi : 10.1139 / b84-391 .
- PE Kolattukudy: Biopolyester Membranes of Plants: Cutin and Suberin . In: Science . 208, No. 4447, 1980, pp. 990-1000. doi : 10.1126 / science.208.4447.990 .