Presence of phospholipid-vesicles in the apoplast of sunflower seeds.

GEORGINA CORTI MONZÓN; MARIANA REGENTE; LAURA DE LA CANAL

Rosario, Santa Fe, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The phospholipids(PL)-rich plasma membrane separates the symplast from the apoplast and couples perception of extracellular factors with intracellular biochemical responses. Hence, PL participates in diverse intracellular signaling cascades but the putative role of PL in transferring the reverse information (from a cell to the extracellular context) has not been studied yet. We have recently hypothesized on the participation of PL in plant extracellular signaling events and we have reported the presence of PL in the extracellular fluid (EF) of sunflower seeds. Since PL are insoluble in aqueous fluids the aim of this work was to determine their organization in the sunflower apoplast. The EF was subjected to fractionation by centrifugation steps at 10000g, 40000g and 100000g and the pellets analyzed by transmission electronic microscopy.  The observation revealed the presence of particles of 120 nm in the 10000g and 40000g pellets, with apparent membrane organization as multivesicular compartments. The characterization of these fractions indicates the presence of PL and proteins, showing a differential content in each fraction. The organization of specific PL and proteins in vesicular structures resembles those of animal systems which have been proposed to participate in the intercellular communication.