N-Acylated phospholipid metabolism and seedling growth: insights from lipidomics studies in Arabidopsis

Abstract

N-Acylphosphatidylethanolamines (NAPEs) are precursors of endogenous bioactive lipids, N-acylethanolamines (NAEs). NAPEs, which occur as a minor membrane lipid, are hydrolyzed in a single enzymatic step catalyzed by a type of phospholipase D (PLD) to generate fatty acid ethanolamides. Although, the occurrence of NAPE is widespread in the plant kingdom, the physiological roles remain under appreciated due to the lack of sensitive tools to quantify the pathway metabolites. In Kilaru et al. (2012, Planta, DOI 10.1007/s00425-012-1669-z), comprehensive mass spectrometry (MS)-based methods were developed to gain a clearer understanding of the complex network of metabolites that participate in NAE metabolic pathway. This targeted lipidomics approach allowed insights to be drawn into the implications of altered NAE levels on NAPE content and composition, and the overall regulation of PLD-mediated hydrolysis in Arabidopsis. Based on these results, we point out here the important need for the identification of the precise isoform(s) of PLD in plants that is (are) involved in the regulated hydrolysis of NAPE and formation of NAE lipid mediators in vivo.

Figure 1. Formation of N-acylethanolamine (NAE 18:2) by phospholipase D (PLD)-mediated hydrolysis of N-acylphosphatidylethanolamine (N-acyl head group is 18:2). NAEs, when present in excess amounts, may regulate PLD activity by feedback inhibition, leading to NAPE accumulation. R' and R” are O-acyl moieties of N-acylphosphatidylethanolamine.