Differential interaction of synthetic glycolipids with biomimetic plasma membrane lipids correlates with plant biological response

Natural and synthetic amphiphilic molecules including lipopeptides, lipopolysaccharides
and glycolipids are able to induce defense mechanisms in plants. In the present work, the
perception of two synthetic C14 rhamnolipids, namely Alk-RL and Ac-RL, differing only
at the level of the lipid tail terminal group, have been investigated using biological and
biophysical approaches. We showed that Alk-RL induces a stronger early signaling
response in tobacco cell suspensions than does Ac-RL. The interactions of both synthetic
RLs with simplified biomimetic membranes were further analyzed using experimental and
in silico approaches. Our results indicate that the interactions of Alk-RL and Ac-RL with
lipids were different in terms of insertion and molecular responses and were dependent on
the lipid composition of model membranes. A more favorable insertion of Alk-RL than
Ac-RL into lipid membranes is observed. Alk-RL forms more stable molecular assemblies
than Ac-RL with phospholipids and sterols. At the molecular level, the presence of sterols
tends to increase the RLs’ interaction with lipid bilayers with a fluidizing effect on the
alkyl chains. Taken together, our findings suggest that the perception of these synthetic
RLs at the membrane level could be related to a lipid-driven process depending on the
organization of the membrane and the orientation of the RLs within the membrane and is
correlated with the induction of early signaling responses in tobacco cells.