Occurrence and Implications of the N-Acylethanolamine Metabolic Pathway in Physcomitrella patens

N-acylethanolamines (NAEs) with C12-C18 acyl chain are ubiquitous in seed plants and play a role in mediating abscisic acid (ABA)-dependent or -independent responses to stress. In moss Physcomitrella patens, using selective lipidomics approach, we recently identified the occurrence of anandamide or N-arachidonylethanolamide (NAE 20:4) and its precursors that were previously not reported in plants. Occurrence of anandamide in moss provides us with a unique opportunity to address if early land plants retained NAE-mediated signaling mechanism that is akin to animals but not to vascular plants. It is hypothesized that a distinctive NAE profile and metabolic pathway occurs in P. patens. To this extent, putative genes that might be responsible for anandamide metabolic pathway were identified and their expression levels were determined for three developmental stages of moss. The NAE metabolite levels and transcript levels for putative genes were higher in protonema stage and anandamide showed higher growth inhibitory effects, chlorophyll reduction, and putative gene induction than NAE 12:0, compared to ABA, when applied exogenously