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Reference : UMR7263-MARCOC-004
Workplace : MARSEILLE 03
Date of publication : Tuesday, June 23, 2020
Scientific Responsible name : Elena ORMENO-LAFUENTE
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
The PhD student with work about the Physico-chemical defense strategies of Mediterranean forests under restricted raining in the field. Assessing the forest capacity to drought adaptation is a major issue mainly in the Mediterranean region where summer drought periods become more frequent and long-lasting and climatic models indicate these changes will accelerate and intensify through the XXI century. Such quick climate change can thus impact forest functioning in turn limiting their ecosystem and societal services.
To understand these strategies, the project will aim to evaluate 1) the occurrence of trade-offs between morphological et metabolomic modifications in foliage with a focus on the specialized metabolome, 2) the link between production, tissue localization and biological functions of some metabolites. This study is thereby integrative since it considers several scales: from the molecule (specialized but also primary metabolites), to the leaf as a whole, going through leaf surface and tissues. This study will mainly be carried out at the Quercus pubescens forest in the experimental site O3HP (at Saint Michel l'observatoire), located 100 km in North of Marseille. Herein, this forest is submitted to rain exclusion since 2012 in order to intensify drought constraint. Field measurements will roughly take place every 3 months.
The candidate will use 1) several imaging techniques (e.g. scanning electron microscopy, confocal and optical microscopy, polarized raman spectroscopy) in order to characterize the internal and external leaf structure and localize different metabolites, 2) instrumentation that allows to characterize plant physiological stress (water potential, gaz exchanges) 3) several techniques such as spin trapping coupled to EPR (electron paramagnetic resonance) to evaluate the oxidant pressure in leaves, indicator of the vegetation physiological stress, 4) analytical instrumentation to characterize the produced metabolites through GC-MS (targeted metabolism) and UHPLC QTof (untargeted metabolism).
The IMBE, particularly the team DFME (Diversity and Fonctionning : from molecules to ecosystems), has being working for 20 years on specialized metabolites from vegetation with a focus on Mediterranean species. These studies are related to several environmental topics such as the role of these metabolites on health, development and functioning of vegetation formations under environmental constraints, with a focus on water deficit in the Mediterranean region. Within the 10 last years, the team has selected the Downy oak forest (Quercus pubescens) as model since it is representative of deciduous forests with a remarkable water deficit resistance.
The main host laboratory will be IMBE (Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale, UMR 7263 CNRS, Aix Marseille University, IRD, Avignon University). More particularly, the PhD student will be related to the DFME team located at Marseille. The secondary host laboratory will be the ICR (Institut de Chimie Radicalaire, Marseille). The student will collaborate also with researchers from the Institut Fresnel.
Constraints and risks
A stay abroad of about 1 month will be envisioned at INIA (Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria) with the aim to analyze foliage tissues through optical microscopy. The field work will imply various journeys at O3HP (Observatoire de Haute Provence) 100 km North Marseille about every 2 - 3 months. The candidate will have to be autonomous during the travels (which implies to possess the driving car license and its own car).
Required profile : The student needs to have a university Master degrees or an engineering degree in environmental sciences, or biology or chemistry and have performed several research internships in domains related to plant ecophysiology, and/or chemical ecology and/or organic and structural organic chemistry. Since this is a pluridisciplinary project, skills within at least one of the 3 profiles (ecology, ecophysiology and chemistry) are sought but an affinity for the other scientific domains are required too. It is also required that the candidate appreciates field and laboratory work, possess skills on statistics and be interested on data treatment. The candidate needs to be dynamic, motivated to receive some training about complementary domains to the initial background, possess writing skills (English and/or French) for reports and scientific papers and organization and communication skills. A B2 English level is required at least.
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