Journal Article

Phospholipids are present in extracellular fluids of imbibing sunflower seeds and are modulated by hormonal treatments

Mariana Regente, Georgina Corti Monzón and Laura de la Canal

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 3, pages 553-562
Published in print February 2008 | ISSN: 0022-0957
Published online January 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/erm329
Phospholipids are present in extracellular fluids of imbibing sunflower seeds and are modulated by hormonal treatments

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Phospholipids are well known messengers involved in developmental and stress responses mediating intracellular signalling. It has been hypothesized that phospholipids exist which could participate in intercellular communication events through the apoplast of sunflower (Helianthus annuus) seeds. Here it is shown that extracellular washing fluids (EWFs) obtained from seeds imbibed for 2 h contain diverse phospholipids. Lipid profiling by electrospray ionization tandem mass spectrometry revealed that the EWFs have a particular composition, with phosphatidic acid (PA) and phosphatidylinositol (PI) being the major phospholipids. These profiles are clearly distinct from those of seed extract (SE), and comparative SDS–PAGE of EWF and SE, followed by intracellular and plasma membrane marker analyses, allowed a significant contamination of the EWF to be discarded. Treatment of the seeds with 100 μM jasmonic acid (JA) induces changes in the profile of EWF phospholipids, leading to a decrease in PI content, while the accumulation of phosphatidylinositol 4-phosphate (PI4P) and specific PA species is observed. On the other hand, the EWF from seeds subjected to 50 μM abscisic acid (ABA) treatment exhibit an increase in PA and phosphatidylglycerol levels. To our knowledge, this is the first report on the existence of phospholipids as extracellular components of seeds. Moreover, the modulation of PA, PI, and PI4P levels by hormonal treatments further suggests their contribution to intercellular communication in planta.

Keywords: Apoplast; phospholipids; seed; sunflower

Journal Article.  6547 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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