User:Daniel Mietchen/Talks/MPI-ICE 2012/Workshop/Cyclo-Oxylipin-galactolipids

Cyclo-Oxylipin-galactolipids are galactolipids containing cyclic oxylipins. They are also often referred as arabidopsides. Mainly they consist out of one or more of the oxylipins 12-oxophytodienoic acid (OPDA) and/or its C16 analog dinor-oxophytodienoic acid (dnOPDA) esterified to monogalactosyl diacylglycerol (MGDG) or digalactosyl diacylglycerol (DGDG). They were found to make up for a major portion of the total OPDA/dnOPDA content. Until now different structures with OPDA/dnOPDA bound to the SN1 and/or SN2 position, as well as to the 6’position of the galactose were found.

Types
MGDG-O , arabidopside A , arabidopside B , arabidopside C , arabidopside D , arabidopside E , arabidopside F , arabidopside G

Similar substances with a substitution of the galactosyl glycerol by a phosphoglycerol are also found.

Appearance
Up to now they were only found in the aerial part of plants from the genus Arabidopsis. They seem to be mainly, if not totally located to the thylakoid membranes of the chloroplasts.

Function
It is still not clear what their main function is. Nevertheless a few processes were found were they seem to be involved. Since OPDA/dnOPDA can be metabolized to jasmonic acid (JA). OPDA/dnOPDA containing galactolipids are assumed to contribute in JA formation. Additionally they were found to accumulate after different stresses like wounding and perception of the bacterial avirulence proteins. Additionally they were found to have growth inhibiting effects on Botrytis cinerea and OPDA can be released out of them by treatment with insect and fungal lipases. This indicates a role in plant defense against bacterial and fungal pathogens and herbivores. Other properties are senescence-promoting effects, growth inhibition of cress roots and they seem to be associated to the photosystems.