Understanding the role of Rab GTPases in plant immunity

Postma, Jelle (2018) Understanding the role of Rab GTPases in plant immunity. Doctoral thesis, University of East Anglia.

Preview

PDF Download (7MB) | Preview

Abstract

Plants employ cell-surface localized receptor-like kinase (RLK) and receptor-like protein (RLP)-type pattern recognition receptors to monitor their surroundings for the presence of infectious pathogens. RLPs interact with the SUPPRESSOR OF BIR1-1 (SOBIR1) RLK for stability and signaling, but it is unclear how signaling is activated. Here, I reveal that the SERK3 RLK is recruited to the tomato Cf-4 RLP upon activation by the Cladosporium fulvum effector Avr4, followed by Cf-4-SOBIR1 co-internalization into late endosomes/multivesicular bodies (LE/MVBs). This extends known RLK-type early activation mechanisms and subcellular localization changes to RLP-SOBIR1-based detection systems, pointing at a widely generalisable mechanism for receptor turnover. Secretory and endocytic membrane trafficking pathways underlie the potentiation and execution of defence. Membrane-associated Rab GTPases are critical regulators of specific pathways, and accumulate at pathogen infection sites, yet their roles in immunity are poorly understood. Here, proteomic analysis of the secretory ARA5/RABD2a complex upon elicitation with bacterial flagellin revealed increased secretion of several uncharacterized RLKs and modules of cell-surface based chemical defences. Comparison between proteomic changes on ARA5/RABD2a and the endocytic ARA7/RABF2b points at flagellin-induced turnover of cell-surface proteins that monitor cell wall integrity and function in processes involving reactive oxygen species. ARA7/RABF2b concentrated under bacterial infection sites, and upon flagellin elicitation recruited the atypical resistance proteins TIR-NBS3 (TN3) and HOMOLOG OF RPW8 4 (HR4). TN3 and HR4 were required for immunity against non-adapted powdery mildew and could be monitoring Rab GTPase-mediated endosomal activity in plant defence.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Users 9280 not found.
Date Deposited:	21 May 2019 08:55
Last Modified:	21 May 2019 08:55
URI:	https://ueaeprints.uea.ac.uk/id/eprint/71079
DOI:

Downloads

Actions (login required)

View Item