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Doctoral thesis, 2021

Insights into biotic stress response in Arabidopsis thaliana : the roles of epigenetics and RNA silencing

Annacondia López, María Luz;

Abstract

Plants live in fluctuating environments that can lead to stressful conditions that threat their survival. To deal with these disturbances, plants have developed a fascinating genome plasticity that enables them to reprogram their gene expression and adapt to the new conditions. Among the different genome plasticity mechanisms, two are key regulators of the stress response: epigenetic regulation and RNA silencing. In this work we explored the roles of epigenetics and RNA silencing during two important biotic stresses, aphid (Myzus persicae) infestation and Cucumber mosaic virus (CMV) infection. We focused on the impact of changes on small RNAs (sRNAs), DNA methylation and repressive histone marks on gene expression and, hence, their role in the stress response. In both stresses, the sRNA populations are connected to the canonical role of the RNA-directed DNA methylation mechanism. Nevertheless, in the case of CMV, its interaction with the RNA silencing is more complex, as it involves the production of viral siRNAs (vsiRNAs) that interfere with the host ARGONAUTE (AGO) proteins and impact host gene expression. Additionally, we showed that DNA methylation plays an essential role in the regulation of the transcriptional response to both aphids and viruses, although it follows different trends. While aphid infestation leads to an important loss of DNA methylation, CMV causes an overall gain. Moreover, histone modifications also have essential functions during both stresses, highlighted by the enhance resistant of kyp to aphids and the reorganization of H3K9me2 and H3K27me3 observed during CMV infection, which are also connected to the changes on DNA methylation and the regulation of the transcriptional defense response. Altogether, this doctoral thesis provides key contributions to improve our knowledge about epigenetics, RNA silencing and their involvement in the regulation of the biotic stress response in Arabidopsis thaliana.

Keywords

Epigenetics; RNA silencing; gene expression; TEs; DNA methylation; histone modifications; sRNAs; AGOs; defense response

Published in

Acta Universitatis Agriculturae Sueciae

2021, number: 2021:58
ISBN: 978-91-7760-794-6, eISBN: 978-91-7760-795-3
Publisher: Department of Plant Biology, Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Plant Biology

UKÄ Subject classification

Genetics

URI (permanent link to this page)

https://res.slu.se/id/publ/113283