Abscisic acid enhancement of lipid vesicle aggregation

Abstract Abscisic acid (ABA) is shown to enhance the rate of aggregation of sonicated phospholipid vesicles as measured by a change in light scattering. Bilayers consisting of pure phosphatidylcholine (PC) remain stable in the presence of ABA as do bilayers of mixed components above their phase transition temperatures. ABA-induced aggregation was measured for phosphatidylcholine vesicles below the phase transition temperature when a second membrane component (phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidic acid (PA) or stearylamine (SE)) was added. Aggregation is dependent upon the concentration of ABA, the concentration of the second membrane component, and pH of the surrounding solution. These findings further support the hypothesis that ABA is causing membrane instability by interacting with bilayers at the interface between different phospholipids.