Characterization of membrane structure modifications induced during plant defense signaling

SPE IPM UB INRA DOCT SPE IPM UB INRA DOCTSPEIPMUBINRADOCTPlasma membrane was long considered as a simple separation between internal and external cellular environment. But more, it is a dynamic interface, an exchange platform. Now, recent researches highlight its role in plant defense responses to biotic and abiotic stresses. We use the tobaccocryptogein model to study the early steps of plant cell responses to pathogen detection. The signaling cascade includes an oxidative burst triggering an increase of plasma membrane order. The level of membrane order informs us about both packing and arrangement of membrane components, this parameter being evaluated by spectrofluorimetric approaches using a lipidic environment-sensitive probe: the di-4-ANEPPDHQ. Here we focus on mechanisms responsible for membrane order increase and the associated increase of ordered domains amount. Two complementary hypotheses could explain such modifications of plasma membrane biophysical properties. Firstly, vesicular traffic could bring sterols (molecules regulating lipid packing) to plasma membrane in response to pathogen and increase ordered domain abundance. Secondly, a modification in the structure of sterols by the direct exposure to reactive oxygen species produced during the defense response could induce a more compact assembling