Oxylipins are involved in plant protections processes and are potential biocontrol agents

Nowadays, biopesticides have emerged as a main alternative to conventional agriculture. In this
context, plant oxylipins, a vast and diverse family of secondary metabolites originated from
polyunsaturated fatty acids (PUFAs), appear to be crucial agents in plant defence mechanisms. Among plant oxylipins, the 13-hydroperoxy oxylipins (13-HPO) constitute key intermediate oxylipins (KIOs) as they can be converted into jasmonic acid, OPDA, dn-OPDA or traumatic acid, well-characterized components involved in plant resistance mechanisms [1][2]. Their presumed functions include direct antimicrobial effect, stimulation of plant defence gene expression, and/or regulation of plant cell death [3]. Otherwise, OPDA and dn-OPDA were also found esterified in more complex structures such as galactolipids. Those compounds are called arabidopsides. However, the precise contribution of each of those molecules in plant defence remains unknown.
The first part of this study aims to understand the oxylipins action mechanisms and especially
their membrane activities. As arabidopsides are produced under stress and localized at the chloroplast membranes, their interactions with those were studied using biomimetic membranes via a complementary in silico informatics and in vitro biophysical approaches. On the other hand, as KIOs are found in the literature to be potential biocontrol agents, there effect on different pathogens of agronomic interest were studied in vitro, by the same approach. As far as arabidopsides are concerned, results show that they possess different interfacial properties compared to major chloroplast lipids, which they are produced from. Arabidopsides modify the fluidity and permeabilize chloroplast membranes. As chloroplast membrane lipid composition is
essential to its photosynthetic ability, such changes in its composition under stress will affect its
function. Concerning KIOs, they seem to interact with pathogens plasma membranes. Indeed, in vitro assays show that KIOs can hinder growth of some plant microbial pathogens, with differences between strains and KIOs forms.