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Investigating the role of ATR1 in pathogenicity and RPP1 mediated resistance in Arabidopsis

Reference	BB/D015731/1
Principal Investigator / Supervisor	Professor James Beynon
Co-Investigators / Co-Supervisors	Dr Anne Rehmany
Institution	University of Warwick
Department	Warwick HRI
Funding type	Research
Value (£)	350,829
Status	Completed
Type	Research Grant
Start date	01/04/2006
End date	31/08/2009
Duration	41 months

Abstract

The oomycete downy mildew pathogen, Hyaloperonospora parasitica, infects the model plant Arabidopsis in the wild. Analysis of the interaction between these organisms has revealed an extensive set of host resistance genes complemented by a range of avirulence genes in the pathogen. The resistance genes and matching avirulence genes reveal high levels of polymorphism suggesting that a co-evolutionary 'arms race' is occurring between plant and pathogen. Previously we have cloned the host resistance gene, RPP1-Nd, and we have recently cloned the matching pathogen avirulence gene, ATR1. In other interactions avirulence proteins have been shown to interact with host proteins that may play a role in basal immunity and that resistance genes have evolved to detect such interactions. We have shown that RPP1 genes from different Arabidopsis accessions have different recognition profiles and that RPP1-WsB is also capable of recognising different alleles of ATR1. We now wish to use this genetic diversity to understand the role of ATR1 in establishing a successful infection of Arabidopsis. To achieve this we will identify the host target of various ATR1 alleles and confirm these interactions in planta. By using mutations in and over expression of the target genes we will assess their role in host immunity. We will also identify the amino acids required to trigger RPP1 mediated recognition of ATR1 and whether or how RPP1 interacts with the host targets of ATR1. In this way, we will use ATR1 to reveal part of the plant host defence mechanisms and contribute to the growing picture of plant immune mechanisms.

Summary

Disease causing organisms, such as bacteria, viruses and fungi, infect their hosts by producing attack proteins that are targeted at suppressing host defence responses. Animals have developed an immune system that recognises the invader and produces a new protein (antibody) that attacks the disease-causing organism. Plants lack this sort of somatically adaptive immune system but face the same invaders. They have produced a different set of highly variable genes called resistance genes. These are thought to recognise the presence of the pathogen attack proteins and respond by causing a plant defence reaction. We have isolated one of these pathogen attack proteins that triggers a particular resistance gene. We now want to find out which plant protein is its target. This will show us which plant protein the pathogen thinks is important and, therefore, it is likely to play an important role in plant defence against disease. We will also learn how this attack protein triggers the resistance response via the plant resistance gene. By assembling the components of this resistance complex we will learn how plants defend themselves against disease. In the future we would hope to use this information to enhance plants' natural defence capability or to develop new products that prevent pathogen growth.

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	Crop Science, Microbiology, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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