Uncovering the epigenetic component of plant-herbivore interactions
- Autores: Anupoma Niloya Troyee
- Directores de la Tesis: Mª Concepción Alonso Menéndez (dir. tes.), Monica Medrano Martinez (codir. tes.)
- Lectura: En la Universidad Pablo de Olavide ( España ) en 2024
- Idioma: español
- Programa de doctorado: Programa de Doctorado en Medio Ambiente y Sociedad por la Universidad Pablo de Olavide
- Materias:
- Enlaces
- Resumen
This PhD thesis is framed within the research field of Ecological Epigenetics, focused in understanding how complex phenotypes arise from a given genotype, and how important epigenetic mechanisms and environmental factors are in shaping this process. The thesis was developed within the EpiDiverse European Training Network, dealing into the epigenetic contribution to plant-herbivore interactions in non-model species. The experimental part focused on two plant species widely distributed in Europe, with different life histories: Thlaspi arvense, often referred as annual field pennycress, and Populus nigra cv. 'italica' or Lombardy poplar. Structured into four chapters, the thesis begins with a comprehensive review of epigenetics' role in plant responses to diverse biotic stressors. Subsequent chapters explore the significance of changes in DNA cytosine methylation after different treatments of experimental herbivory in the two focal plant species, using three available techniques that differ in their costs (sample processing, time and price) and technical requirements (analytical tools, annotated reference genome), and including a comparison of the output produced by two Next Generation Sequencing techniques based on the analysis of DNA treated with bisulfite, the reduced representation epiGBS and the Whole Genome Bisulfite Sequencing (WGBS). The results show for the two plant species that changes in cytosine methylation have a population-specific nature and differed depending the damage is conducted by insect caterpillars (hereafter, insect herbivory) or experimentally simulated by punching the leaves and spraying jasmonic acid (hereafter, artificial herbivory). In particular, the study on T. arvense shows that global DNA methylation decreases after herbivory, with the magnitude of change being greater in the artificial treatment and varying with seed provenance. Additionally, it indicates that the reduction of global DNA methylation caused by the demethylating agent 5-azacytidine applied at the seed stage, also differed in the magnitude between seed provenances. In P. nigra cv. 'italica', herbivory induced cytosine methylation changes mainly in the CHH context, in sequences located at intergenic regions, and with a notable overlap of these changes with transposable elements. Altogether, the studies presented within this PhD thesis provide valuable insights, although they also point to the need for further research (e.g., transcriptome analysis) to confirm the direct links between DNA methylation changes and gene expression under specific environmental conditions. The emergence of reference genome-free tools opens avenues for high-resolution plant epigenetic analysis in non-model species, demonstrating that some techniques that do not required high-quality genomic resources, such as epiGBS, can be a cost-effective and useful for characterizing genome-wide methylation changes in response to herbivory, as here demonstrated for poplar. In conclusion, this PhD thesis significantly advances current understanding of ecological plant epigenetics, offering a new perspective and deeper molecular understanding on plant-herbivore interactions.
