Fatty Acid Amide Hydrolases and Chemical Communication in Plants

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Plants use small molecules as signals to synchronize their growth, development and responses to their environment. This project seeks to understand how an evolutionarily-conserved group of plant enzymes utilizes chemical signals to regulate growth and to influence their microbial environment. Specific research aims include the discovery of new enzymes and their substrate molecules that act as communication signals. Broader applications of this research may offer new strategies to enhance agricultural outputs by manipulating plant-microbe interactions in crop and soil systems. In addition, the proposed research activities are integrated with undergraduate training opportunities through a research course at the University of North Texas, a large minority-serving, public university. The three-dimensional structure of the Arabidopsis fatty acid amide hydrolase (AtFAAH) complexed with a diverse range of acylamide substrates helped to identify key residues involved in substrate interactions. By comparing FAAH sequences from 87 plant species, conserved differences in these key residues in the binding pocket revealed two distinct groups of FAAHs, expanding further the types of small molecule substrates that might be recognized by these enzymes. Based on these new, structure-driven inferences, and the demonstrated promiscuity of AtFAAH (group I), this proposal will investigate the role of FAAH proteins more broadly in the interaction of plants with their microbial environment and in the internal modulation of plant growth. The overarching hypothesis is that FAAH acts in an axis of communication through hydrolysis of small molecule acylamides to both surveil the biotic environment and adjust plant growth and development. The hypothesis will be tested in two plant species with multiple FAAH genes and with known microbial interactions that involve FAAH substrates through three aims. 1) Characterize the effects of FAAH suppression on plant growth and microbiomes of both G. hirsutum and M. truncatula. 2) Evaluate the metabolite changes in FAAH-altered plants through metabolomics platforms. 3) Examine substrate ranges for group I and group II FAAH through ex vivo lipidomics analysis and in vitro enzyme assays. The objectives of this research proposal will be integrated more broadly with training opportunities for 32 undergraduate students through two offerings of a classroom undergraduate research experience (CURE) at the University of North Texas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.