Comparative Genomics Approach to Pathway Discovery and Engineering in Tomato Trichomes

Schenck Craig A, Lansing MI

Investigators

Abstract

This action funds an NSF National Plant Genome Initiative Postdoctoral Research Fellowship in Biology for FY 2018. The fellowship supports a research and training plan in a host laboratory for the Fellow who also presents a plan to broaden participation in biology. The title of the research and training plan for this fellowship to Dr. Craig Schenck is "Comparative Omics Approach to Pathway Discovery and Engineering in Tomato Trichomes" The host institution for the fellowship is Michigan State University and the sponsoring scientist is Dr. Robert Last. Metabolites produced in spatial and temporal manner, are the drivers to plant form and function. These metabolites are assembled from organic building blocks in a complex web of enzymatic reactions and allow plants to thrive in diverse environments. Many specialized metabolites are involved in ecological interactions, but also provide humans with diverse metabolites of nutritional and medicinal importance. The diversity and taxonomic restriction of plant specialized metabolism allows for discovery of novel biochemical reactions, and investigation of evolution on a macro and micro level. Fundamental understanding of the production of biologically active plant specialized metabolites will have broad impacts on improving nutrition and performance of crops. Specifically, increasing biologically active plant metabolites in agronomically important species provides a means to enhance crop defenses and productivity. This project will provide a fundamental understanding of how enzymes and metabolic pathways evolve, the principles of which can be applied to agriculture and extended to understand evolution in other biological systems. Training objectives include functional genomics, analytical chemistry, and bioinformatics. Broader impact activities include mentoring and training graduate and undergraduate students and organizing outreach events to raise public awareness of the plant sciences. Plants produce a myriad of lineage-specific specialized metabolites (e.g. alkaloids, terpenes, etc.), which are synthesized from essential primary metabolites like amino acids. Many specialized metabolites are involved in ecological interactions, but also provide humans with diverse metabolites of nutritional and medicinal importance. Evolution of specialized metabolism tends to occur more quickly than evolutionarily constrained primary metabolism. This recent evolution in plant specialized metabolism has given rise to hundreds of thousands of structurally diverse metabolites found in the green plant lineage. The diversity and taxonomic restriction of plant specialized metabolism allows for discovery of novel biochemical reactions, and investigation of evolution on a macro, metabolic pathway, and micro, enzyme, level. Sugar esters (acylsugars) are a group of specialized metabolites restricted to many species within the nightshade family (Solanaceae) that consist of a sugar core decorated with diverse acyl chains and have plant defense and commercial properties. The acyl chains attached to acylsugars vary in number, length, and branching pattern, which gives rise to natural variation in acylsugar types and abundance within Solanaceae. Branched-chain amino acids are the direct precursors of C4-C5 acyl chains, but synthesis of longer acyl chains requires elongation. However, the biochemical mechanisms responsible for chain elongation remain unknown. This project will leverage the wealth of data encompassing the Solanaceae to identify biochemical mechanisms and evolutionary processes leading to the diversity of acylsugars. Using comparative genomics, transcriptomics, metabolomics, biochemistry and traditional genetics, this project aims to identify and biochemically characterize the acyl chain elongation pathway in tomato and closely-related wild relatives, validate in vitro biochemistry by testing the in vivo function of the identified enzymes, and engineer the Solanum acyl chain elongation pathway in Nicotiana benthamiana to reconstitute the pathway and enhance production of biologically active acylsugars. All data obtained through this project will be submitted to publicly available websites and repositories and manuscripts will be published in open access journals. Keywords: biochemistry, specialized metabolism, defense compounds, acylsugar, chain elongation 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.