N-Acylethanolamines: Emerging Lipid Mediators of Seedling Development
 
Elison B. Blancaflor1,* and Kent D. Chapman2
1 Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
2 Department of Biological Sciences, University of North Texas, Denton, Texas, USA
*email: eblancaflor@noble.org
 
N-Acylethanolamines (NAEs) are lipid mediators derived from the hydrolysis of the membrane phospholipid, N-acylphosphatidylethanolamine (NAPE). In animal systems, this reaction constitutes part of the endocannabinoid signaling pathway, which regulates a variety of physiological processes, including cell proliferation, immune cell signaling, neurotransmission, and embryo development. NAEs have been identified and quantified in a variety of plant tissues, and reports of biological activities of these lipids in plants are rapidly emerging. For example, NAEs have been implicated in the signal-mediated activation of gene expression, the inhibition of phospholipase D (PLD) alpha activity, and the regulation of ABA-induced stomatal closure. NAEs are prevalent in desiccated seeds and are metabolized rapidly during imbibition. We have shown previously that sustained levels of NAE12:0 have profound effects on Arabidopsis seedling growth and development, which includes a reduction in primary root and cotyledon expansion, increased radial swelling of root tips, and an inhibition of root hair initiation. Light and electron microscopic analysis of Arabidopsis roots reveal that the effects of NAE12:0 also are apparent at the cellular level as defects in cell division, cytoskeletal organization, membrane dynamics, and cell wall organization. We have developed a battery of tools that we expect will help in extending our understanding of NAE function in seedling development in Arabidopsis thaliana. These tools will be supported by sensitive quantitative procedures (gas chromatography/mass spectrometry) for determining endogenous levels of NAEs in plant extracts. Characterizing the effects of NAEs on seedling growth through these interdisciplinary approaches should provide new insights into the regulation of plant development by this endogenous group of bioactive lipids.
 
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