Transgenerational effects and physiological responses to drought recurrence in holm oak (Quercus ilex) – TRANSfER

The overarching goal of this project is to quantify and understand the physiological impacts of drought recurrence in trees as well as the role of potential transgenerational epigenetic regulation in the adaptation of trees to drought recurrence events. Specifically, we will focus on how a history of long-term drought on the parent trees affects the physiological underpinnings of carbon, nitrogen and water balance of holm oak (Quercus ilex L.) of the offspring saplings facing drought recurrence events, as well as their mycorrhizal symbionts. We will concentrate on the following four interrelated objectives:

1) Investigate/quantify the potential transgenerational effects of long-term drought (>13 years) on acorn germination, seedling establishment and performance.
2) Assess the impact of drought recurrence events and release (during rainfall pulse events after drought) on the physiology and plasticity of carbon, nitrogen and water acquisition and use.

3) Investigate the impact of water regime history (long-term drought) of the parent trees on the diversity and composition of mycorrhizal communities of the offspring saplings together with the impact on tree carbon, water and nitrogen allocation under experimentally-induced drought recurrence events.

4) Investigate the putative epigenetic origin of any transgenerational adaptive effects (memory of drought) and its potential links with tree physiological responses and ectomycorrhizal symbionts.

To this end, we will take advantage of a long-term field experiment (the CNRS Puéchabon, near Montpelier France) and a unique controlled environment facility for ecosystem research (the CNRS Montpellier European Ecotron, Montferrier-sur-Lez, France). The simultaneous use of three isotopic tracers (13C, 15N and Deuterium) will permit to track the fate of carbon, nitrogen and water from leaf to ecosystem level. By combining the identification of epigenetic marks with gene expression and assessments of the consequences of transgenerational memory for the acquisition and allocation of water, nutrient and carbon in trees and forest ecosystems, this project will help closing an important knowledge gap in our understanding of how a keystone Mediterranean tree species (Q. ilex) might acclimate and adapt to future climatic conditions. Therefore, our project is fully in line with the ANR’s identified grand societal challenge entitled “Sustainable resource use and adaptation to climatic change” (“Gestion sobre des ressources et adaptation au changement climatique”).