Soutenance de Thèse de Laura Garcia De Jalon

Ce vendredi 11 décembre à 14h, Laura GARCIA DE JALON  soutiendra sa thèse  intitulée "Exploring the effects of microhabitat, ectomycorrhiza and epigenetic regulation on the establishment and performance of holm oak (Quercus ilex L.) in a drier world" en visioconférence.

lien vers la diffusion publique : à venir

Résumé: Mediterranean forests are facing an increase in the intensity and duration of droughts due to climate change, with potentially severe consequences for tree mortality and regeneration dynamics. This thesis investigates the potential carry-over drought effects that may affect the establishment, performance and survival of holm oak (Quercus ilex L.) seedlings alongside physiological and epigenetic modifications in mature trees. Specifically, it explores (i) the effects of microhabitat and ectomycorrhizal colonization on the establishment and survival of seedlings, (ii) the effects of drought on the diversity and composition of fungal communities and the subsequent consequences on seedling survival, and (iii) the effects of drought on the epigenetic modifications and physiological responses manifested in mother trees, which have the potential to be adaptive and enhance seedling survival. This thesis represents an interdisciplinary approach combining epigenetics, biotic interactions and environmental effects in a long-term drought experiment (15 years) with a reduction of 29% in annual precipitation in a Q.ilex forest in the south of France. Our results showed that even though summer drought was the main cause of seedling mortality, the precipitation reduction treatment increased the survival of seedlings compared to ambient conditions. This unexpected result was related to an increase in the ectomycorrhizal richness and an increase of drought adapted ectomycorrhizal species under drier conditions. Mother trees presented acclimation responses to drought that were correlated to changes in the methylome which suggest a potential role of epigenetics regulating these responses and a potential intergenerational transmission. This thesis provides evidence of the remarkable resilience to drought stress of the Mediterranean forests species, where recurrent environmental fluctuations may have favoured the emergence of long-term adaptation legacies.

Composition du jury :

Composition du jury:

Mme Monique Gardes, Professeur, EDB, Toulouse - rapporteur
M. Stéphane Bazot, Professeur, ESE, Orsay - rapporteur
Mme Claude Plassard, DR, INRAE - examinateur
Mme Mar Sobral, Researcher, U. Santiago de Compostela - examinateur
M. Philippe Balandier, DR, INRAE - examinateur
M. Franck Richard, Professeur, Université de Montpellier - Directeur de thèse
M. Alexandru Milcu, CR, CNRS - encadrant
M. Jean-Marc Limousin, CR, CNRS  - encadrant