Understanding the role of kiwifruit EXO70 proteins in plant defence

Massey University

About the Project

Background:

The plant exocyst complex, which tethers secretory vesicles to membranes, has recently emerged as an important battleground in plant-pathogen and plant-pest interactions [1]. The EXO70 proteins of this complex are of particular interest, as they have recently been shown to be involved in plant immunity against diverse pathogens and, in line with this, are targeted for modulation by pathogen virulence factors termed effectors [2–5]. Notably, plants have evolved resistance (R) proteins that interact with EXO70 proteins, indicating that they monitor these exocyst components for modulation by pest and pathogen effectors. For example, Arabidopsis EXO70B1 has been shown to interact with TN2, an atypical Nucleotide-binding Leucine-Rich Repeat (NLR) R protein [6]. Furthermore, several independent examples of R proteins requiring an EXO70F protein partner have been reported in rice, wheat and barley [3,7], while a brown plant hopper R protein (Bph6) from rice has recently been shown to interact with two EXO70 proteins from the EXO70E and EXO70H clades [8].

Aims:

The aims of the advertised PhD project are to understand the role of kiwifruit (Actinidia spp.) EXO70 proteins in plant defence, and to determine whether effector proteins of the kiwifruit canker pathogen, Pseudomonas syringae pv. actinidiae (Psa), modulate these EXO70 proteins to promote host susceptibility (A. chinensis) or resistance (A. melanandra).

Initial project objectives:

1)     Characterize in planta interactions between EXO70 family members, other proteins from kiwifruit (some of which have been shortlisted based on preliminary data), and Psa effectors using split GAL4 RUBY [9], co-immuno-precipitation (Co-IP), and proximity labelling assays [10–11] in conjunction with Agrobacterium tumefaciens-mediated transient transformation assays (ATTAs) [12] in Nicotiana benthamiana.

2)     Assess the functional relevance of key interaction residues identified in previous modelling using site-directed mutagenesis in conjunction with experimental techniques listed in 1).

3)     Visualise the in planta dynamics of EXO70 protein localisation in the presence or absence of other proteins from kiwifruit in 1) and Psa effectors using confocal laser scanning microscopy.

Applicants should have a strong interest in molecular plant–microbe interactions, and a first or upper second class BSc(Hons) or MSc degree in Molecular Plant Pathology, Plant Molecular Biology, Molecular Microbiology, Genetics, or related disciplines. Experience in microscopy, plant pathology, fungal biology, proteomics, bioinformatics, or genomics/transcriptomics would be an advantage.

Massey University is a leading New Zealand University for postgraduate study, and is one of the QS-ranked top 60 Universities in the world for Agriculture & Forestry. The supervisory team will include Dr Carl Mesarich (Primary Supervisor; School of Agriculture and Environment, Massey University, Palmerston North, New Zealand), Dr Erik Rikkerink (Co-supervisor; The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand), and Prof. Professor Viktor Žárský (Co-supervisor; Charles University, Prague, Czech Republic). The scheduled start date for the PhD project can be as early as February 1 2023, but will start as soon as a suitable candidate is found.

To apply, please send a curriculum vitae, motivation letter, academic transcripts (both undergraduate and postgraduate) and contact details (preferably email addresses) of at least two academic referees to Dr Carl Mesarich () before the closing date (30 September, 2023). Shortlisted applicants will be interviewed by Zoom in October 2023.

General information:

Informal inquiries can be directed to Dr Carl Mesarich ().

Applicants must meet Massey University admission requirements:

https://www.massey.ac.nz/massey/admission/entry-requirements/eligible_home.cfm.

Minimum English requirements for international applicants are detailed at: https://www.massey.ac.nz/massey/international/study-with-massey/entry-requirements/entry-requirements_home.cfm#PG.

Further information on postgraduate study at Massey University can be found at: https://www.massey.ac.nz/massey/postgraduate/postgraduate_home.cfm.

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