DOE OSTI2018
Research in our labs, supported since 2005 by Basic Energy Sciences, has led to the discovery of a new lipid mediator pathway that influences phytohormone-mediated regulation of plant growth and development—the so-called N-acylethanolamine (NAE) regulatory pathway. This pathway in plants shares conserved metabolic machinery with the endocannabinoid signaling system of vertebrates that regulates a multitude of physiological and behavioral processes in mammals, suggesting that the metabolism of NAEs is an important regulatory feature of eukaryotic biology. Current evidence in plants points to interactions between NAE metabolism, abscisic acid (ABA) signaling and light signaling to modulate seedling establishment and the acquisition of photoautotrophic growth. The proposed research fits well within the mission of Photosynthetic Systems and Physical Biosciences which seek “to understand the processes by which plants, algae and non-medical microbes capture, convert and/or store energy”. The fundamental regulatory processes that govern seedling establishment directly influence the assembly of photosynthetic energy conversion systems in essentially all higher plants. Our main hypothesis is that seedlings coordinate the metabolic depletion of NAEs during seedling establishment through a complex interaction of hydrolysis (by fatty acid amide hydrolase, FAAH) and oxidation (by lipoxygenases, LOX) and that newly-reported oxylipin metabolites of polyunsaturated NAEs help to coordinate seedling development and acquisition of photoautotrophy in response to appropriate environmental cues. Evidence suggests that ethanolmide oxylipins derived from NAEs can reversibly accumulate in seedlings and adjust/arrest seedling establishment and chloroplast development in conjunction with ABA signaling and light-signaling pathways. Our results provide important new information linking the production of small molecule lipid mediators in seedlings to the coordinated development of photoautorophy. While relevant to how plants capture, convert and store energy, this work also extends to the general understanding of acylethanolamides and their bioactivity in eukaryotic organisms. In addition, analytical mass spectrometry methodology developed in this work also helped to demonstrate the identification, quantification and spatial localization of NAEs and other lipids in various plant and animal tissues. Cumulative scholarly output includes 45 publications, 2 U.S. Patents, and 24 invited research seminars. This research funding also supported the training of 2 master’s students, 4 Ph.D. students and 3 postdoctoral scholars, enhancing the human infrastructure of the U.S. science enterprise.