Fatty Acid Amide Hydrolases Mediate N-Acylethanolamine Hydrolysis in Tomato

N-acylethanolamines (NAEs) are a diverse family of signaling lipids that occur in eukaryotes and their presence is specific to developmental stage and tissue type. In plants, NAEs with an acyl chain ranging from C12 to C18 are common with NAE 18:2 generally being the most abundant type, particularly in desiccated seeds. In Arabidopsis, NAEs negatively regulate growth and mediate stress responses via abscisic acid-dependent and -independent signaling pathway. The function of NAEs is terminated by a highly conserved fatty acid amide hydrolase (FAAH). Because of the significant role NAEs were shown to play in model plant Arabidopsis it is pertinent to elucidate this conserved metabolic pathway in crop species such as tomato. It is hypothesized that NAE pathway occurs in tomato and that there is a functional FAAH that hydrolyzes NAEs.To test this hypothesis, NAE content and composition will be determined in various tissues and developmental stages of tomato by selective lipidomic analysis. Furthermore, a functional homolog of AtFAAH has been identified in tomato and will be biochemically characterized.Thus far, full-length coding sequence of SlFAAH1 and SlFAAH2 were isolated and cloned into a heterologous expression system. The expressed protein will be characterized for its hydrolytic activity against radiolabelled NAE substrates. Temporal expression of SlFAAH1 and SlFAAH2 in different tissues will also be analyzed by quantitative PCR to correlate with the NAE levels. The molecular and biochemical characterization of FAAH in addition to determining the composition of NAEs in tomato will further validate the conserved nature of NAE metabolic pathway in plants