Environmentally induced DNA methylation variation: A high-resolution study for unravelling the methylome plasticity and functionality in the Lombardy poplar

Summary

This thesis explores the potential of epigenetic modifications as plant mechanisms to cope with challenging environments. Specifically, it delves into the role of DNA methylation in response to various stressors, including drought, cold, heat, insect herbivory, fungal infection, and plant hormone application in Lombardy poplar trees. I sought to understand how stress-specific is the induced methylation variation, what is the role of these methylation responses on transcriptional regulation, and to what extent poplar trees are able to memorize stress experiences. I identified genomic regions in which methylation changes occur irrespective of the stress treatment (generic methylation response), and a specific hypermethylation in response to drought. In addition, I developed a tool, RustSpotter, to quantify leaf rust infection, which allowed me to detect increased susceptibility to rust fungal disease when trees were previously exposed to biotic stressors. This thesis highlights the complexities of integrating methylation and transcriptomics data, emphasizing the need for further research to understand the mechanisms underlying stress-induced DNA methylation changes. The thesis expands knowledge of DNA methylation in poplar responses to water shortage and suggests potential for future research using epigenetic reprogramming tools like CRISPR/dCas systems.