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Project Details
Project status
In progress
Research Framework
Pou Tokomanawa
Research Duration
Jul 2024 - Feb 2028
Project Overview
For fungal pathogens to successfully colonise plants and cause disease, they must deliver a collection of virulence factors called effectors into and around plant cells. In susceptible hosts, these effectors typically function to suppress the plant immune system. However, in resistant hosts, one or more of these effectors can be specifically recognized by immune receptors (resistance proteins) to activate defence responses that stop fungal growth. This resistance, however, can often be broken through mutations in (or loss of) the genes encoding the recognised effectors.
Using a range of new and existing molecular biology tools (see the objectives below), this project will investigate how the scab pathogen, V. inaequalis, promotes disease susceptibility or resistance in apple at the molecular level. Here, the focus will be on the interaction between the AvrRvi4 effector protein of V. inaequalis and its corresponding host proteins in apple (the Rvi4 resistance protein and virulence targets of AvrRvi4).
Why This Matters
Fungal pathogens pose a major threat to Aotearoa New Zealand’s native and productive plants. Research into how these pathogens promote disease susceptibility or resistance is desperately needed to inform durable disease control strategies, but would greatly benefit from improved genetic tools. In addition to existing tools, this project will harness different CRISPR-Cas phage defence systems to establish a suite of new genetic tools in the fungal pathogen responsible for apple scab disease, V. inaequalis. Scab was chosen as a model because it is the most economically important disease of apples in Aotearoa New Zealand, with apples the second largest fruit export. Should the tools be useful, they can then be applied to other diseases that threaten other plants of Aotearoa New Zealand.
Impacts
A better understanding of the role that pathogen effectors play in promoting host susceptibility and resistance using new tools could lead to innovative, durable disease control strategies. For example, if an individual effector is found to only play a significant role in pathogen virulence when combined with other members of the effector family to which it belongs, one method could involve engineering a host resistance protein that recognises all effector family members. Likewise, if an individual effector is found to play a significant role in pathogen virulence, the virulence target of the effector in the host could be engineered so that it no longer interacts with the effector. This would, in turn, decrease the ability of the pathogen to colonise its host and cause disease.
Project Objectives
- Determine the localisation of the AvrRvi4 effector during infection of apple by V. inaequalis using fluorophore protein fusions and confocal microscopy.
- Assess whether there is an interaction between the AvrRvi4 effector and Rvi4 resistance protein by determining whether they elicit a hypersensitive response in Nicotiana species (non-hosts) and apple.
- Identify host protein targets in apple using yeast-two-hybrid and protein pull-down/co-immunoprecipitation experiments.
- Utilise protein modelling tools to predict the structure of the AvrRvi4 effector protein and examine potential contact points for interacting with the Rvi4 resistance protein.
- Use CRISPR-Cas gene editing technologies to knockout or disrupt the AvrRvi4 effector gene in V. inaequalis (and other members to which the AvrRvi4 effector family belongs) and assess the impacts on the virulence of the pathogen.
