A regulatory role for N-acylethanolamine metabolism in Arabidopsis thaliana seeds and seedlings.

A regulatory role for N-acylethanolamine metabolism in Arabidopsis thaliana seeds and seedlings.

Date: May 2009
Creator: Teaster, Neal D.
Description: N-Acylethanolamines (NAEs) are bioactive acylamides that are present in a wide range of organisms. Because NAE levels in seeds decline during imbibition similar to ABA, a physiological role was predicted for these metabolites in Arabidopsis thaliana seed germination and seedling development. There is also a corresponding increase of AtFAAH (fatty acid amide hydrolase), transcript levels and activity, which metabolizes NAE to ethanolamine and free fatty acids. Based on whole genome microarray studies it was determined that a number of up-regulated genes that were responsive to NAE were also ABA responsive. NAE induced gene expression in these ABA responsive genes without elevating endogenous levels of ABA. It was also determined that many of these NAE/ABA responsive genes were associated with an ABA induced secondary growth arrest, including ABI3. ABI3 is a transcription factor that regulates the transition from embryo to seedling growth, the analysis of transcript levels in NAE treated seedlings revealed a dose dependent, inverse relationship between ABI3 transcript levels and growth, high ABI3 transcript levels were associated with growth inhibition. Similar to ABA, NAE negatively regulated seedling growth within a narrow window of early seedling establishment. When seedlings are exposed to NAE or ABA within the window of sensitivity, ...
Contributing Partner: UNT Libraries
Interactions of N-Acylethanolamine Metabolism and Abscisic Acid Signaling in Arabidopsis Thaliana Seedlings

Interactions of N-Acylethanolamine Metabolism and Abscisic Acid Signaling in Arabidopsis Thaliana Seedlings

Date: August 2010
Creator: Cotter, Matthew Q.
Description: N-Acylethanolamines (NAEs) are endogenous plant lipids hydrolyzed by fatty acid amide hydrolase (FAAH). When wildtype Arabidopsis thaliana seeds were germinated and grown in exogenous NAE 12:0 (35 µM and above), growth was severely reduced in a concentration dependent manner. Wildtype A. thaliana seeds sown on exogenous abscisic acid (ABA) exhibited similar growth reduction to that seen with NAE treatment. AtFAAH knockouts grew and developed similarly to WT, but AtFAAH overexpressor lines show markedly enhanced sensitivity to ABA. When low levels of NAE and ABA, which have very little effect on growth alone, were combined, there was a dramatic reduction in seedling growth in all three genotypes, indicating a synergistic interaction between ABA and NAE. Notably, this synergistic arrest of seedling growth was partially reversed in the ABA insensitive (abi) mutant abi3-1, indicating that a functional ABA signaling pathway is required for the full synergistic effect. This synergistic growth arrest results in an increased accumulation of NAEs, but no concomitant increase in ABA levels. The combined NAE and ABA treatment induced a dose-dependent increase in ABI3 transcript levels, which was inversely related to growth. The ABA responsive genes AtHVA22B and RD29B also had increased expression in both NAE and ABA treatment. ...
Contributing Partner: UNT Libraries
N-Acylethanolamine (NAE) profiles change during Arabidopsis thaliana seed germination and seedling growth.

N-Acylethanolamine (NAE) profiles change during Arabidopsis thaliana seed germination and seedling growth.

Date: August 2006
Creator: Wiant, William C.
Description: An understanding of the potential roles as lipid mediators of a family of bioactive metabolites called N-acylethanolamines (NAEs) depends on their accurate identification and quantification. The levels of 18C unsaturated NAEs (e.g. NAE18:2, NAE 18:3, etc.) in wild-type seeds (about 2000 ng/g fw) generally decreased by about 80% during germination and post-germinative growth. In addition, results suggest NAE-degradative fatty acid amide hydrolase (FAAH) expression does not play a major role in normal NAE metabolism as previously thought. Seedlings germinated and grown in the presence of abscisic acid (ABA), an endogenous plant hormone, exhibited growth arrest and secondary dormancy, similar to the treatment of seedlings with exogenous N­lauroylethanolamine (NAE12:0). ABA-mediated growth arrest was associated with higher levels of unsaturated NAEs. Overall, these results are consistent with the concept that NAE metabolism is activated during seed germination and suggest that the reduction in unsaturated NAE levels is under strict temporal control and may be a requirement for normal seed germination and post-germinative growth.
Contributing Partner: UNT Libraries