Subcellular dynamic of ozone injury and detoxification processes within tree foliage
PI : Yves Jolivet (UMR 1137 Ecologie et Ecophysiologie Forestières – EEF)
Co-applicants : Mireille Cabané, Dany Afif, A Gandin, Didier Le Thiec, Marie-Noëlle Vaultier (UMR 1137 Ecologie et Ecophysiologie Forestières – EEF)
Collaborations : Marcus Schaub, Pierre Vollenweider (WSL, Birmensdorf, Switzerland)
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Context — With background concentrations having reached phytotoxic levels during the last century, tropospheric ozone (O3) has become a key agent in climate change, counteracting carbon sequestration by forest ecosystems. Recently, O3 flux-based critical levels for the vegetation, using dose-response functions with e.g. O3 damage and reduced growth, have been established. However, one of the main gaps for those functions concerns the assessment of the effective O3 flux leading to adverse effects, which primarily depends on detoxification processes within foliage.
Objectives — The main objective of this project is to provide an innovative mechanistic and integrative understanding regarding the dynamics of cellular processes leading to visible O3 injury in foliage. The modifications in carbon allocation and biomass productivity will be studied as a consequence of symptom development. The interaction between oxidative constraints (ozone and drought) will also be investigated.
Approaches — Using the phytotron facility at the Lorraine University, we plan to perform a series of O3 exposure experiments under controlled conditions. Micropropagated trees from a hybrid poplar clone (Populus tremula x Populus alba INRA 717-1-B4) will be exposed to O3 for a few weeks and foliage material sequentially sampled with a view to integrative of structural, molecular and physiological analyses. Specific analyses using innovative methodologies will be performed by collaborating with genomic and microscopy centers. Metabolite determination and 13C labeling will be also performed.
Expected results and impacts — By resolving the spatiotemporal scale of O3 damage in foliage, we will be able to disentangle the defensive, degenerative and hypersensitive responses and relate them to corresponding effective O3 dose. We thus expect decisive advance in current understanding regarding the complex interplay between oxidative stress and plant defense.
