Lipid Profile Reveals Occurrence of Anandamide (A Mammalian Neurotransmitter) in Physcomitrella

Improving crop yield by generating stress tolerant plants is the enduring objective of this research. A small class of bioactive fatty acid derivatives, N-acylethanolamines (NAEs), including anandamide (NAE 20:4), an endocannabinoid receptor ligand, affects a wide range of physiological and behavioral functions in animals. In plants, NAEs to the exclusion of anandamide are found to be ubiquitous and abundant in seed tissues and are shown to be involved in mediating abscisic acid (ABA) -dependent or -independent stress responses. Early land plants such as Physcomitrella patens (moss) have been shown to tolerate abiotic stresses. We hypothesized that NAEs are involved in mediating stress responses in moss. Gas chromatography-mass spectrometry was employed in NAE detection and quantification in moss. Selective lipidomic approach revealed novel NAE metabolites. The endocannabinoid receptor ligand anandamide and its precursor molecules were detected and quantified. Exogenous treatment of NAE 12:0, NAE 20:4 and ABA showed a growth inhibitory effect for all three metabolites. NAE 20:4 was more potent than NAE 12:0 to degrees similar to the plant hormone ABA. In silico analyses of NAE catabolizing enzyme fatty acid amide hydrolase from Arabidopsis showed eight putative FAAH candidates in this moss. Candidates showed high similarities with plants as well as animal FAAH proteins. Primers specific to NAE pathway genes have been designed for expression analysis. Our recent identification of the ligand NAE 20:4 in this moss, provides us with a unique opportunity to address if 1) early land plants, such as mosses, retained the endocannabinoid signaling mechanism that is akin to animals but not to plants and 2) if such distinctive NAE profile and mechanism by which it may function in moss plant is responsible, in part, for their natural ability to resist high temperatures, dehydration, osmotic and salt stresses. Insights into unique lipids composition and signaling pathways that mosses acquire naturally, during their successful transition from water to land, may lead to development of tools necessary to enhance abiotic stress tolerance in vegetative tissues of higher plants and thus contribute to improvement of crop productivity