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Suppression of extracellular host hydrolases by a plant pathogen

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  • Full or part time
    Prof R Van der Hoorn
  • Application Deadline
    Applications accepted all year round

Project Description

The extracellular space in leaves (the apoplast) is an important battlefield for plant-pathogen interactions. Plants defend this space by the (induced) secretion of hydrolytic enzymes. Adapted pathogens are likely to suppress these enzymes using inhibitors but these interactions and their relevance to the plant-pathogen interaction are largely unknown. We have used activity-based proteomics to study the interaction between the model bacterial pathogen Pseudomonas syringae and the model tobacco-relative Nicotiana benthamiana. This revealed the activation of 70 hydrolases (mostly serine hydrolases) and suppression of 25 hydrolases (mostly glycosidases and cysteine proteases) during infection (Sueldo et al., ms in prep.). We discovered that one of the suppressed glycosidases acts in immunity by releasing a key elicitor from bacteria (submitted ms). We expect similar and other important roles for the other suppressed hydrolases.
The AIM of this project is to study the role and mechanisms of hydrolase suppression during infection by identifying substrates of relevant hydrolases and elucidate the underlying suppression mechanisms. First, relevant hydrolases will be identified by virus-induced gene silencing (VIGS) and genome editing using CRISPR/Cas9, followed by pathogen infection assays. Next, we aim to identify inhibitory metabolites or small proteins and remove the inhibitor-encoding genes from P. syringae to determine their role during infection. In parallel, substrates will be identified by proteomic and metabolomic studies and using glycoarrays and molecular modelling.
This challenging, exciting discovery project involves molecular biology, biochemistry and protein work on plants and pathogens and is embedded in a highly productive, international research team taking complementary approaches to improve molecular pharming, study pathogen recognition and pioneer chemical proteomics in plants.


We are looking for an enthusiastic DPhil student with experience in molecular cloning and a passion for working with plant pathogens with an international and interdisciplinary research team.


There are three application deadlines, but you are strongly encouraged to apply in November or January.

- Friday 16 November 2018
- Friday 25 January 2019
- Friday 1 March 2019

* Note: Applications must be submitted by 12 noon (midday) on these days.

Please ensure that you contact potential supervisors well in advance of these deadlines. Later applications may be considered if places are available.

Funding Notes

Prospective students are encouraged to apply to the Oxford Interdisciplinary Bioscience DTP. International applicants are encouraged to explore scholarship options that are available to them through the University of Oxford, their home countries or organisations such as the Commonwealth Scholarship Commission.


Shindo et al. (2016) Screen of non-annotated small secreted proteins of Pseudomonas syringae reveals a virulence factor that inhibits tomato immune proteases. PLoS Pathog. 12, e1005874.
Ilyas et al. (2015) Functional divergence of two secreted immune proteases of tomato. Curr. Biol. 25, 2300-2306.
Dong et al. (2014) Effector specialization in a lineage of the Irish potato famine pathogen. Science 343, 552-555.

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