Nippe, Olivia M. (2019) Identification and characterisation of microbial effectors interfering with the plant circadian rhythm. PhD thesis, University of Warwick.

Preview

PDF WRAP_Theses_Nippe_2019.pdf - Submitted Version - Requires a PDF viewer. Download (24Mb) | Preview

Request Changes to record.

Abstract

Infection of economically important crops by rapidly evolving pathogenic bacteria poses an on-going threat to food security, often causing substantial loss to crop yields. Such aggressive pathogens rely on the delivery of virulence factors, known as effectors, for the suppression of plant immunity and to ensure successful infection of the host (Buttner et al., 2016). One posited mediator of Arabidopsis thaliana defence is the circadian clock, which regulates susceptibility to invading pathogens, and the expression levels of immune receptors in a temporal fashion (Bhardwaj et al., 2011; Wang et al., 2011b). While this rhythmicity enables the plant to maximise efficiency of its immune system through synchronisation with the environment, it also makes the circadian oscillator a likely target for manipulation by bacterial effectors. This project aimed to identify effectors in the Pseudomonas syringae repertoire capable of disrupting circadian rhythmicity and characterise their mechanism of action. Our use of bioluminescence detection assays indicates that secretion of specific effectors by P. syringae significantly influences the rhythmic expression of A. thaliana core clock genes. Through the large-scale transcriptomic analysis of stable transgenic lines expressing the Pst effector HopAO1 with targeted sub-cellular localisation we present evidence that HopAO1 significantly reduces clock gene expression in a way that is dependent on its previously uncharacterised function in the nucleus. Assessment of HopAO1’s interaction partners by Y2H reveals it is able to interact with two closely related NAC transcription factors and enhance their binding of the LHY promoter. We propose that HopAO1 alters the clock and enhances Pst virulence by interacting with the two NAC transcription factors in order to repress core clock gene expression. It is hoped that the characterisation of the molecular mechanisms employed by effectors such as these will permit the engineering of more disease resistant crops.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QK Botany Q Science > QR Microbiology S Agriculture > SB Plant culture
Library of Congress Subject Headings (LCSH):	Plant circadian rhythms, Plant circadian rhythms -- Molecular aspects, Phytopathogenic microorganisms, Plants -- Disease and pest resistance
Official Date:	September 2019
Dates:	Date Event September 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Ntoukakis, Vardis
Format of File:	pdf
Extent:	210 leaves : illustrations
Language:	eng

Request changes or add full text files to a record

Repository staff actions (login required)

View Item

Downloads