2-Phenylethanol and its derivatives in poplar-insect and poplar-microbe interactions

Background: In response to herbivory, many plants produce defense compounds which can either be toxic or repellant for the herbivore or attractive for natural enemies of the herbivore. These direct and indirect defenses present strong barriers against various attackers. 2-Phenylethanol (2PE) is an amino acid-derived volatile compound that is produced by a multitude of plant species. It has been reported to function as a volatile signal in different plant-insect interactions such as the attraction of natural enemies of plant herbivores and the attraction of pollinators. Moreover, 2PE has been shown to possess antimicrobial properties. Poplar trees are known to produce 2PE as a major volatile in response to herbivory. Additionally, they accumulate high amounts of 2PE-glucose (2PE-Glc) in undamaged leaves. However, the potential role of volatile 2PE and non-volatile 2PE-Glc in indirect and direct poplar defense is unclear.

Project Description: The first aim of this project is to investigate the biological role of 2PE and 2PE-Glc in poplar-insect interactions. The PhD candidate will perform bioassays to test whether pure 2PE and 2PE-Glc can influence insect herbivore behavior and performance. Later, transgenic trees with altered levels of 2PE and 2PE-Glc will be used for in vivo bioassays. Using modern analytical techniques such as GC-MS and LC-MS/MS, the PhD candidate will also study the spatial and temporal pattern of herbivore-induced 2PE emission and constitutive 2PE-Glc accumulation in poplar trees.
While the herbivore-induced formation of volatile 2PE has been recently elucidated in poplar, the biochemical pathway leading to constitutive accumulation of 2PE-Glc is still unclear. Since endophytic fungi isolated from poplar leaves are able to produce 2PE in vitro, we hypothesize that they contribute to 2PE/2PE-Glc formation in planta. To test this hypothesis, the PhD candidate will compare 2PE emission and 2PE-Glc accumulation in sterile and inoculated poplar trees. Furthermore, he/she will apply a transcriptomics approach to identify fungal and plant genes responsible for 2PE-Glc biosynthesis. Gene candidates will be tested in heterologous systems and enzyme characterization will be performed in vitro using enzyme assays and in vivo using transgenic poplar plants.

Candidate profile: We look for a candidate with a Master´s degree or equivalent who has a strong background in molecular ecology, biochemistry, and/or plant physiology. Highly motivated students with solid training in other areas of biology or biochemistry are also encouraged to apply. We offer an excellent research environment with enthusiastic scientists from different nationalities in the Department of Biochemistry (director: Prof. Jonathan Gershenzon) at the Max Planck Institute for Chemical Ecology in Jena, Germany.