engleski

Characterization of the expression of transcriptionally silent loci during the plant response against Pseudomonas syringae

The results presented in this thesis support the notion initially proposed by recent studies of RNA- directed DNA methylation (RdDM) and transcriptional gene silencing (TGS) having an important role in plant defence against phytopathogenic bacteria (Pumplin and Voinnet, 2013). Dampening defence gene expression through RdDM could provide an effective mode of regulation because RdDM can be rapidly reversed by biotic and abiotic stress. The rapid activation of plant defences would require the presence of RdDM-prone genomic segments (transposons and repeats) in the vicinity of defence-related genes and the involvement of active demethylation pathways to ensure optimal and rapid defence gene induction on pathogen attack. In addition, the dampening of RdDM and the resulting defence gene activation occurs only transiently, to prevent the prolonged induction of these stress-responsive plant genes. This feature is foreseeably advantageous in the case of defence- related genes whose continuous expression reduces plant fitness. In such a model, the acquisition of effectors capable of directly or indirectly suppressing this activation would represent a clear advantage for plant pathogenic bacteria.

Plant-pathogen interaction, gene expression, Epigenetics

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