Abstract :

Plants are sessile organisms that must respond and adapt to abiotic and biotic constraints. Agricultural production and ecosystem functioning are frequently constrained by drought episodes, the frequency and duration of which are expected to increase under the influence of climate change. The study of interactions between plants, their pathogen and vector communities and the abiotic environment is still not sufficiently integrated into water limitation issues. In order to improve the understanding of interactions between plants and viruses under water deficit conditions, we evaluated the effects of CaMV on the growth strategies of several A. thaliana genotypes grown in a phenotyping automaton as well as the effect of WD on CaMV viral traits and their relationship. This work allowed us to i) characterise the growth and fitness response of A. thaliana to CaMV under WD conditions by exploiting the natural diversity of a Spanish population ii) relate important traits related to plant functional strategy to stress tolerance iii) show that WD can modify important CaMV-related traits such as transmission or intra-host accumulation iv) study the trade-off on the natural diversity of A. thaliana genotypes under optimal irrigation conditions or under WD. This study thus highlighted the importance of understanding the impact of the environment on the pathogenicity of the virus and its persistence within an ecosystem, but also of associating the inherent strategies of the plants to the tolerance of the virus. The multidisciplinary approaches constitute the richness of this thesis work, which contributes to a better characterisation and understanding of the response of plants during a viral infection and a water deficit.