Identification and characterisation of MOB proteins as regulators of innate immunity in Arabidopsis thaliana

George, Jeoffrey (2020) Identification and characterisation of MOB proteins as regulators of innate immunity in Arabidopsis thaliana. Doctoral thesis, University of East Anglia.

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Cell-surface pattern recognition receptors sense invading pathogens by perceiving elicitors such as microbial patterns, and activate innate immunity. These responses are often under tight control to avoid excessive or untimely activation of cellular responses, which may otherwise be detrimental to host cells, but how this fine-tuning is accomplished remains mostly unknown. A forward genetics suppressor screen was performed to identify Arabidopsis thaliana mutants that regained immune signalling in the immunodeficient genetic background bak1-5. This screen led to the identification of 10 modifier of bak1-5 (mob) mutants. Here, I report that bak1-5 mob7, 8, 9 and 10 restore elicitor-induced signalling, with some specificities in their responses to the different elicitors tested. Through map-based cloning and next-generation mapping, the mob7 causative mutation was mapped to the gene CONSERVED BINDING OF EIF4E1 (CBE1) encoding a plant-specific RNA-binding protein (RBP). CBE1 represents a novel RBP involved in immune signalling, regulating elicitor-induced reactive oxygen species production potentially by controlling the protein level of the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D. Furthermore, various mRNA decapping and translation initiation factors co-localised with CBE1 and regulate immune signalling, similarly as CBE1. The results of this project led to the current working model in which, by analogy to mammalian translational regulation, CBE1 acts as a translation repressor within processing-bodies by controlling mRNA turnover. This study thus identified a novel regulator of immune signalling and provides new insights into the regulation of translation in plants.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 07 Oct 2021 14:24
Last Modified: 07 Oct 2021 14:24

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