Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.585540
Title: Molecular basis of plant cell death suppression by the Phytophthora infestans effector AVR3a
Author: Chaparro Garcia, Angela
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2012
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Abstract:
Plants actively perceive pathogens and activate their immune system upon pathogen recognition. The first encounter with the pathogen relies on the recognition of highly conserved microbial molecules known as pathogen-associated molecular patterns (PAMPs) by cell surface receptors called pattern-recognition receptors (PPRs). Successful pathogens have evolved effectors to overcome plant defense and to colonize their host. INF1 is a P. infestans elicitin with features of PAMPs that requires the co-regulator receptor-like kinase SERK3/BAK1 to trigger cell death. AVR3a is an effector translocated by P. infestans that suppresses INF1-triggered cell death (ICD). However, the potato protein R3a can recognize AVR3a. The avirulence and suppression activities of this effector are conditioned by distinct amino acids but the precise series of events leading to ICD suppression by AVR3a, the nature of the INF1 receptor, and the composition of the receptor complex remain unknown. This study investigates mechanisms underlying AVR3a interference with basal immunity and its importance for P. infestans pathogenicity. Homologs of SERK3/BAK1 in N. benthamiana were shown to be required for resistance against P. infestans. To further our understanding of the molecular events after INF1 elicitation, a receptor-like protein (RLP) implicated in ICD was characterized. Using a combination of fluorescence microscopy and biochemistry, I showed that this RLP localizes to the endoplasmic reticulum and plasma membrane and forms a complex with SERK3/BAK1. I assessed the extent to which AVR3a interferes with SERK3/BAK1-dependent signaling pathways and found that variants of AVR3a suppress defense responses elicited by diverse PAMPs to different degrees. Additional plant proteins interacting with AVR3a were searched using in planta complex purification and mass spectrometry analysis. A host GTPase (dynamin) protein involved in endocytosis was found. Dynamin was shown to be required for ICD suppression activity by AVR3a. Notably, dynamin accumulates around P. infestans (Pi) haustoria possibly pointing to its role in the plant-Pi interaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.585540  DOI: Not available
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