Exploiting crosstalk between growth and immunity in plants : the role of the <i>Phytophthora infestans</i> effector AVR2 in potato late blight

Plants are fundamental to life on earth, crucially providing the basis of our food supply. As world population continues to grow, so too does the pressure on our agricultural systems, with one of the biggest challenges being the control of plant pathogens to ensure a healthy crop.<br/><br/>The interaction between plant and pathogen is complex, with subtleties at the molecular level dictating the boundary between health and disease. This is exemplified by pathogen effectors; secreted proteins which enter the plant cell and interact with host targets to facilitate infection. AVR2 is one such effector, secreted by the oomycete pathogen Phytophthora infestans; the pathogen responsible for potato late blight. AVR2 interacts with a family of kelch-repeat containing phosphatases in potato, the BSLs, implicated in brassinosteroid pathway signalling – a major hormone signalling pathway in plants associated with growth and development. This work investigates the role of AVR2 and its host targets in pathogen virulence, with focus on the link between the brassinosteroid pathway and immunity in S. tuberosum.<br/><br/>StBSL1 is shown to be a ‘susceptibility factor’ in P. infestans infection – a host protein with a positive effect on pathogen virulence. AVR2 stabilises BSL1 in planta, and both AVR2 and BSL1 are shown to suppress primary defence responses in the plant.<br/><br/>Transcriptional analysis of brassinosteroid-treated S. tuberosum is used to identify a set of marker genes for active BR signalling. Strikingly, AVR2 is shown to upregulate <br/>this pathway, and specifically upregulates the transcription factor StHBI1-like, identified as a suppressor of immunity.<br/><br/>These findings reveal a novel mechanism in oomycete effector biology; the exploitation of crosstalk between the brassinosteroid pathway and immune signalling in plants.

Name dc:type.qualificationname

Doctor of Philosophy

Level dc:type.qualificationlevel

Doctoral Thesis

Grantor dc:publisher.institution

University of Dundee

Year dc:date.issued

2016

Author dc:creator

• Turnbull, Dionne

Advisors dc:contributor.advisor

• Birch, Paul
• Hein, Ingo

• Potato late blight
• Effectors
• disease resistance
• Plant pathology
• Phytophthora infestans
• Brassinosteroid pathway
• Crosstalk
• Plants
• Growth and development
• Immunity
• PTI
• ETI
• HR
• R protein
• AVR2
• BSL1
• R2
• Food security
• Susceptibility factor

Language dc:language

eng

Identifier

oai:discovery.dundee.ac.uk:studenttheses/757753a0-3d97-49b5-b921-2dd3728f4a2e
https://discovery.dundee.ac.uk/en/studentTheses/757753a0-3d97-49b5-b921-2dd3728f4a2e

OAI identifier oai:identifier

oai:discovery.dundee.ac.uk:studenttheses/757753a0-3d97-49b5-b921-2dd3728f4a2e