Stress-related accumulation of arabidopsides: impact on chloroplast membranes

Oxylipins are crucial agents in plant defense mechanisms. While free oxylipins are well studied, roles of esterified oxylipins remain unclear. Esterified oxylipins are structurally diverse metabolites that were found in diverse plant species, suggesting that those may be more ubiquitous that currently thought. Among those, galactolipids containing (dn)OPDA were discovered, firstly in A. thaliana, but also in other plants. Those molecules, named arabidopsides, are highly induced under stress conditions, as it accumulates up to 8 percent of plant lipids, but their precise contributions in plant defense mechanisms are still unknown. Arabidopsides are directly formed in plant chloroplast membranes from galactolipids. Accumulation of arabidopsides in such high quantity in chloroplast membranes may modify their properties (e.g. photosynthetic activity).
This study aims to understand the impact of arabidopside presence in chloroplast membranes on their properties using biomimetic plant membranes via complementary in silico and in vitro approaches. Interfacial properties of arabidopsides and non-oxidized galactolipids were studied using Langmuir film balance. Results showed that arabidopsides possess different interfacial properties compared to non-oxidized chloroplast lipids. Arabidopsides ability to permeabilize chloroplast membranes was also studied in vitro. Arabidopsides A and B are able to permeabilize chloroplast membranes while arabidopside D is not.
In conclusion, arabidopside production by plants under stress conditions may modify chloroplast membrane properties such as its permeability. As chloroplast membrane lipid composition is essential to its photosynthetic ability, such changes may also affect its function.