PhD position available Evolution of transpiration barrier properties in Aeonium (Crassulaceae) – integrating cuticle chemistry and structure by means of Raman spectroscopy The cuticle is the most important transpiration barrier of plants. Structure and composition of plant cuticular waxes have been shown to influence the transpiration barrier function of the cuticle. We aim to study the role of crystalline wax moieties relative to amorphous wax moieties for the permeance of the cuticle to water. While the genetic basis of cuticular wax biosynthesis and elongation of aliphatic components is increasingly well understood, large-scale studies of cuticular wax chemistry and the corresponding transpiration barrier properties have been unsuccessful in establishing a direct association. While the composition of cuticular waxes is studied by extraction and subsequent chromatographic analysis, the structure of cuticles has been mostly studied using electron microscopy, both being destructive methods. Raman spectroscopy and its applications to the study of plant structure and biochemistry are an emerging field in plant sciences and have recently started to show high potential for in-vivo analysis of the plant cuticle. Raman imaging mapping is well suited to spatially resolve the chemical properties and degree of crystallinity or amorphia in multi-layered objects such as the plant cuticle. It is a minimally invasive method (0.9 μm Spotsize with 100 objective) that only requires simple preparation of the specimen and can therefore be applied to plants from which cuticular membranes cannot be isolated, as is the case in Aeonium. Aeonium is a genus of succulent plants belonging to the most species-rich plant lineage that diversified in the Macaronesian floristic region. It represents a classic case of radiation into different ecological niches. Among 32 of the 41 accepted species of Aeonium, minimum conductance to water has been shown to diverge by two orders of magnitude, underpinning the vast ecological diversity in this genus. Aeonium species also express Crassulacean Acid Metabolism (CAM) to varying degrees, and minimum conductance was shown to be negatively correlated with the level of CAM expressed relative to C3 photosynthetic carbon fixation. This implies that cuticular transpiration barrier properties likely are under selective pressure in the diversification of CAM plant lineages. With this project, we want to (1) test the hypothesis of cuticular wax crystallinity as predictor of cuticular permeance to water and to (2) trace the evolution of and selection pressure on genes underlying cuticular wax biosynthesis that are relevant for the protection against water loss in an ecologically diverse lineage. Eligibility We are looking for a highly motivated candidate with a Master of Science degree in Biology or a related scientific field, fluency in English, an interest in plant physiology, spectroscopic techniques and genomics and a relevant background in plant ecology and evolution. Experience with molecular biological lab methods is essential. Previous experience with spectroscopic lab techniques, analytical chemistry, experimental plant physiology or advanced bioinformatic skills will also be viewed favourably. Position details Supervision: This project will be conducted under the primary supervision of Dr. Thibaud Messerschmid (Botanical Garden Munich-Nymphenburg) and PD Dr. Melanie Kaliwoda (Bavarian State Collection for Mineralogy), as well as Prof. Dr. Gudrun Kadereit (LMU Munich). Location: The Kadereit Working Group at the Institute of Systematics, Biodiversity and Evolution of Plants, Ludwig Maximilian University of Munich (Menzinger Straße 67, 80638 Munich, Germany) and the Botanical Garden Munich-Nymphenburg (Menzinger Str. 65, 80638 Munich) Time-frame: 3 years, November/December 2024 Salary: 65% TVL-E13 Application To apply for this position, please prepare the following (in English): 1. A short (1-2 page) cover letter explaining your motivation for applying for this PhD position 2. Your CV, including 1-2 referees and a publication list (if applicable) 3. A certificate of completion and degree certificate (if not available yet, please state that in your cover letter) Email your application documents as one PDF to Dr. T. Messerschmid (messerschmid@snsb.de). Applications close October 18th, 2024. For further information regarding the application procedure or the project, please contact Dr. T. Messerschmid (messerschmid@snsb.de). This position is funded by the Bavarian Natural History Collections (SNSB). Kind regards, Thibaud Messerschmid Dr. Thibaud Messerschmid Botanischer Garten München-Nymphenburg Postal address: Menzinger Str. 61 80638 München Tel.: +49 89 17861-370 "Messerschmid, Thibaud" (to subscribe/unsubscribe the EvolDir send mail to golding@mcmaster.ca)