NSF-ANR MCB/PHY: Subcellular trafficking and secretion of scent

Purdue University, West Lafayette IN

Investigators

Abstract

Plants emit a wide diversity of volatile organic compounds (VOCs) that play essential roles in reproduction, defense, plant-plant signaling, and abiotic stress responses. They also influence atmospheric chemistry and climate, and are of economic importance to humans. Given the importance of volatiles, significant progress has been made in elucidating the biosynthesis and regulation of plant VOCs, and in recent years, the molecular mechanisms involved in the release of volatiles from cells into the atmosphere. It has been shown that the movement of volatiles across the plasma membrane relies on transporters and non-specific lipid transfer proteins to facilitate their diffusion across the cell wall to the cuticle, the final barrier for VOCs to cross, which acts as a VOC sink/concentrator. Yet, the transport of VOCs to the plasma membrane remains unexplored. This project will investigate the involvement of lipid droplets in VOC intracellular trafficking to the plasma membrane and how toxicity of volatiles via sequestration is prevented. This research will provide new insights into the biological mechanisms of VOC trafficking and storage in plant cells. The results will have a substantial practical impact by uncovering new targets for accumulating valuable compounds or altering their release from the plant. The information gained may also lay the foundation for boosting plants' capability to store lipophilic compounds. The proposed research will provide multidisciplinary training to undergraduate and graduate students, and postdoctoral researchers. The educational program will also introduce STEM-based research to students at a local middle school, with the goals of improving student enthusiasm, interest, and perceptions about scientific careers. This research will employ an integrative strategy comprised of -omics, biochemical and genetic approaches, metabolic profiling, cellular biology, and in situ imaging using coherent Raman techniques to (i) characterize the lipids and specific proteins involved in the formation of lipid droplets in VOC-producing tissues; (ii) elucidate the role of lipid droplets in the emission, storage and/or toxicity prevention of VOCs, and (iii) determine the lipid droplet dynamic changes and their influence on VOC trafficking and/or storage during flower development, a day/night cycle, and in response to changes in temperature. Rose and petunia petals as well as pelargonium leaf trichomes will be used as model systems in this research. Comparative analysis of roses, which emit both terpenoids and phenylpropanoids during the day, and petunia, which emit high levels of phenylpropanoids/benzenoids during the night, will not only determine whether the lipid droplets' contributions to emissions depends on the nature of the VOCs but also uncover if lipid droplet abundances change rhythmically during a daily light/dark cycle correlated with VOC emission. In contrast, analysis of lipid droplets in trichomes will uncover their distinct storage properties, which prevent VOC emission from these extracellular structures. This collaborative US/France project is jointly supported by the Cellular Dynamics and Function program in the Division of Molecular and Cellular Biosciences and the Physics of Living Systems program in the Division of Physics at the US National Science Foundation and the French Agence Nationale de la Recherche, where NSF funds the US investigator and ANR funds the partners in France. 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.