Discovery of Novel N-acylethanolamines in Early Land Plants and Their Implications

N-acylethanolamines (NAEs) are family of lipid-derived signaling molecules in many organisms, which include an endocannabinoid N-arachidonoylethanolamide (anandamide, AEA, NAE 20:4). NAEs, specifically AEA plays pivotal role in mammalian neurological and physiological functions; however their metabolism and functional implications in plants are yet to be fully discovered. Unlike seed plants, bryophytes possess unique fatty acid composition that includes 20:4 and 20:5, which prompted our search for endocannabinods in moss Physcomitrella patens. To this extent, we used targeted lipidomic analyses and discovered long-chain NAEs and their corresponding N-acyl-phosphatidylethalamine (NAPE) precursors in an early land plant species. In protonemal tissues N-arachidonyl-PE and N-20:5-PE contributed to about 49% and 30%, respectively. Matured gametophytes on the other hand showed a 12% increase in N-20:4-PE and 20% decline in N-20:5-PE, relative to NAPE content in protonema. In all haploid developmental stages analyzed NAE 20:4 levels contributed to ~ 23% of the total NAE while NAE 20:5 remained as a minor component (5%). Interestingly, in Selaginella moellendorffi, an early vascular plant N-18:2-PE species was most abundant; although minor amounts of N-20:3-PE, N-20:4-PE and N-20:5-PE were present, only a small quantity of NAE 20:4 was identified among the 20C NAEs. Both AEA and it corresponding fatty acid, arachidonic acid have growth inhibitory effects in a dose dependent manner. Biological implications of anandamide and its metabolic pathway in moss are under investigation. Our data reveals an evolutionarily conserved occurrence of NAE metabolites in early land plants, with an exclusive report of AEA presence in a bryophyte