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Differential Effects of Two Phospholipase D Inhibitors, 1-Butanol and N-Acylethanolamine (NAE), on in vivo Cytoskeletal Organization and Arabidopsis Seedling Growth. C.M. Motes1, K.D. Chapman2 P. Pechter1, C.-M. Yoo1, Y.-S. Wang1, and E.B. Blancaflor1 

1Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK , and 2Department of Biological Sciences, University of North Texas, Denton, TX

   Plant development is regulated by numerous chemicals derived from a multitude of metabolic pathways. However, we know very little about the functions of many of these metabolites in the cell. N-acylethanolamines (NAEs) are a group of lipid mediators that play important roles in mammalian physiology. Despite the similarities between animals and plants in NAE metabolism, not much is known about the precise function of these metabolites in plants. In plants, NAEs have been shown to inhibit phospholipase D (PLD) alpha activity, interfere with ABA-induced stomatal closure and retard Arabidopsis seedling development. 1-Butanol, an antagonist of PLD-dependent phosphatidic acid (PA) production, induced defects in Arabidopsis seedling development that were similar to effects induced by elevated levels of NAE. This raised the possibility that the impact of NAE on seedling growth could be mediated in part via its influence on PLD activity. To address this possibility, we conducted a comparative analysis of the effects of 1-butanol and N-lauroylethanolamine (NAE 12:0) on Arabidopsis root cell division, in vivo cytoskeletal organization, seed germination and seedling growth. Although both NAE 12:0 and 1-butanol induced profound cytoskeletal and morphological alterations in seedlings, there were distinct differences in their overall effects. 1-Butanol induced more pronounced modifications in cytoskeletal organization and cell division compared to NAE 12:0. Futhermore, 1-butanol delayed seed germination and had a more deleterious effect on overall seedling growth compared to NAE 12:0. We propose that these compounds mediate their differential effects on cytoskeletal organization, cell division, and seedling growth, in part through the differential modulation of specific PLD isoforms (Supported by DOE DE-FG02-05ER15647 and NSF DBI 0400580).