AUTHOR=Teaster Neal D., Keereetaweep Jantana , Kilaru Aruna , Wang Yuh-Shuh , Tang Yuhong , Tran Christopher N., Ayre Brian G., Chapman Kent D., Blancaflor Elison B.

TITLE=Overexpression of Fatty Acid Amide Hydrolase Induces Early Flowering in Arabidopsis thaliana

JOURNAL=Frontiers in Plant Science

VOLUME=3

YEAR=2012

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2012.00032

DOI=10.3389/fpls.2012.00032

ISSN=1664-462X

ABSTRACT=<p><italic>N</italic>-acylethanolamines (NAEs) are bioactive lipids derived from the hydrolysis of the membrane phospholipid <italic>N</italic>-acylphosphatidylethanolamine (NAPE). In animal systems this reaction is part of the “endocannabinoid” signaling pathway, which regulates a variety of physiological processes. The signaling function of NAE is terminated by fatty acid amide hydrolase (FAAH), which hydrolyzes NAE to ethanolamine and free fatty acid. Our previous work in <italic>Arabidopsis thaliana</italic> showed that overexpression of <italic>AtFAAH</italic> (<italic>At5g64440</italic>) lowered endogenous levels of NAEs in seeds, consistent with its role in NAE signal termination. Reduced NAE levels were accompanied by an accelerated growth phenotype, increased sensitivity to abscisic acid (ABA), enhanced susceptibility to bacterial pathogens, and early flowering. Here we investigated the nature of the early flowering phenotype of <italic>AtFAAH</italic> overexpression. <italic>AtFAAH</italic> overexpressors flowered several days earlier than wild type and <italic>AtFAAH</italic> knockouts under both non-inductive short day (SD) and inductive long day (LD) conditions. Microarray analysis revealed that the <italic>FLOWERING LOCUS T</italic> (<italic>FT</italic>) gene, which plays a major role in regulating flowering time, and one target MADS box transcription factor, <italic>SEPATALLA3</italic> (<italic>SEP3</italic>), were elevated in <italic>AtFAAH</italic> overexpressors. Furthermore, <italic>AtFAAH</italic> overexpressors, with the early flowering phenotype had lower endogenous NAE levels in leaves compared to wild type prior to flowering. Exogenous application of NAE 12:0, which was reduced by up to 30% in <italic>AtFAAH</italic> overexpressors, delayed the onset of flowering in wild type plants. We conclude that the early flowering phenotype of <italic>AtFAAH</italic> overexpressors is, in part, explained by elevated <italic>FT</italic> gene expression resulting from the enhanced NAE hydrolase activity of AtFAAH, suggesting that NAE metabolism may participate in floral signaling pathways.</p>