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Title: The role of DNA methylation in Arabidopsis immunity
Author: Furci, Leonardo
ISNI:       0000 0004 6424 1153
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2017
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DNA methylation in plants is an epigenetic mechanism controlling genome stability and gene expression. Unlike other epigenetic marks, patterns of DNA methylation can be maintained through meiosis over multiple generations. Recent studies have revealed a role for DNA methylation in plant defence priming, an immune sensitisation mechanism that allows plants to mount a faster and stronger basal defence reaction to pathogen attack, resulting in enhanced resistance. The aim of the study presented in this thesis is to gain insight into the role of DNA methylation in immunity of Arabidopsis thaliana (Arabidopsis). Analysis of Arabidopsis mutants with altered levels of global DNA methylation revealed that DNA methylation represses basal resistance against the biotrophic pathogen Hyaloperonospora arabidopsidis (Hpa), but enhances resistance to the necrotrophic fungus Plectosphaerella cucumerina, suggesting a regulatory function of DNA methylation in innate immune responses. Conversely, systemic acquired resistance was unaffected in these mutants, indicating that DNA methylation does not play a major role in within-generation acquired immunity. To explore the contribution of DNA methylation in heritable disease resistance, a core population of epigenetic recombinant inbred lines (epiRILs) was characterized for disease resistance. This population, which is derived from a cross between Col-0 and the ddm1-2 mutant, shows minimal genetic variation, but varies in DNA methylation at heterochromatic regions, due to inheritance of hypo-methylated DNA from the ddm1-2 parent. There were significant levels of variation in Hpa resistance in the epiRIL population, which could be linked to four epigenetic quantitative trait loci (epiQTLs). Characterisation of eight Hpa-resistant epiRILs revealed that this resistance is associated with priming of salicylic acid (SA)-dependent and SA-independent defence mechanisms. RNA-sequencing analysis of the immune response of four Hpa-resistant epiRILs confirmed this notion, and revealed a potentially novel regulatory mechanism by which DNA hypo-methylated transposable elements in the epiQTLs regulate the responsiveness of defence genes in trans.
Supervisor: Ton, Jurriaan Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available