Intercellular co-ordination of plant defence responses

Lead Research Organisation: John Innes Centre
Department Name: Contracts Office

Abstract

Plant-pathogen interactions are complex and disease incidence depends on a plant’s’ ability to defend itself against pathogen attack. Plant defence strategies are classified into those triggered by PAMP-triggered immunity (PTI), effector triggered immunity (ETI) and systemic acquired resistance (SAR). Each response involves the generation of high concentrations of small, toxic and mobile molecules, which appear to diffuse from the attack site or synthesis into surrounding cells through plasmodesmata (PD), membrane-lined channels that connect plant cells. This implies that localised pathogen attack can be perceived and trigger responses in surrounding cells unless intercellular connectivity is controlled. In support of this hypothesis, I have shown that chitin associated PTI involves a reduction in intercellular connectivity and communication, a response that is mediated via the chitin receptor LYM2. This highlights a role for symplastic isolation in PTI, possibly serving to concentrate small defence-associated molecules at the attack site and protect the surrounding cells from toxic effects. My work is to determine the role of cell-to-cell connectivity and communication in PTI and also in ETI and SAR. In contrast to PTI, SAR is expected to rely on intercellular connectivity for response generation. I am exploiting lym2 mutants and plants where the PD aperture can be genetically manipulated to determine which responses depend upon cellular isolation and/or on intercellular communication and co-ordination. In these plants I will also monitor the spread of defence associated molecules, e.g., Ca2+ and reactive oxygen species, from the site of attack. This study will form the basis for future work that will exploit PAMP-triggered PD closure to enhance resistance against economically damaging pathogens, which in turn this work will contribute to the developing novel strategies with which plant disease can be controlled and secure food production in changing environments.

Publications

10 25 50
 
Description The PDLP proteins were previously identified to be located at plasmodesmata but it was not known what function they served. We fortuitously observed that one of these proteins is also located at downy mildew haustoria during infection, where it controls how much callose is deposited around the haustoria (a defence response). This allowed us to identify that these proteins also control callose deposition at plasmodesmata, which is the mechanism that regulates plasmodesmal response to pathogen perception.

We have identified two effectors of the downy mildew pathogen that can move from cell to cell in host tissues. This suggests that pathogens also access cells beyond those they initially infect.
Exploitation Route Our findings identified a positive regulator of host defence and plasmdoesmal closure, which may find application in strategies to enhance plant resistance.
Sectors Agriculture, Food and Drink

 
Description Norwich Research Park Doctoral Training Programme
Amount £78,000 (GBP)
Funding ID FAULKNER_J17DTP: Dinner for two - how does a pathogen access host resources? 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2017 
End 08/2021
 
Description Pint of Science 2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Pint of Science is an outreach event held in pubs across the country with the aim of taking reseearch andscientific ideas to the general public. I presented in the York Tavern were I estimate 35-50 people attended. The audience were members of the general public.
Year(s) Of Engagement Activity 2017
URL https://pintofscience.co.uk/