EXPLORING ADAPTIVE IMMUNITY IN PLANTS

Lead Research Organisation: Rothamsted Research
Department Name: Biological Chemistry & Crop Protection

Abstract

In their struggle for life, plants strongly rely on inducible defense mechanisms. These defense responses become activated when a plant is attacked by harmful pathogens or insects. Induced defence involves a wide spectrum of different chemical and physical defence barriers, ranging from the induction of toxic metabolites that target the attacker's physiology, to cell wall appositions that prevent invasions by pathogenic fungi. Despite this diversity in defensive strategies, the inducible defense arsenal is not always sufficient to protect the plant against intrusion by pathogens and insects. This is why plants have evolved an additional, more sophisticated, defense system that allows them to fine-tune their inducible defense system. Upon perception of specific environmental cues, plants can develop an enhanced defensive capacity that is effective against a remarkably wide range of different stresses. Interestingly, this induced resistance is not based on direct defence activation by the inducing agent, but on a faster and stronger activation of inducible defence mechanisms at the moment the plant is exposed to stress. This sensitization for defence is called 'priming'. Because priming allows the plant to adjust its inducible defence system to the environmental conditions, it can be regarded as a form of adaptive immunity. Interestingly, stimulation of the plant's adaptive immune system through priming has already been shown to yield broad-spectrum resistance with minimal reductions in plant growth and seed set. This suggests an important ecological function of plant adaptive immunity, which increases the plant's ability to survive in hostile environments. The main objectives of this research proposal are to 1) discover novel key mechanisms by which plants exploit their adaptive immune system, and 2) critically evaluate the ecological advantages that adaptive immunity provides for plants under field conditions. To this end, a multidisciplinary approach will be followed, using state-of-the-art techniques in the field of molecular biology, plant physiology and plant ecology. The outcome of this project will be instrumental for future exploitations of plant adaptive immunity in sustainable agriculture.

Technical Summary

Although research on plant-microbe and -insect interactions has undergone exciting developments, research on plant adaptive immunity is still in its infancy. In this pioneering stage, Arabidopsis thaliana as a model system holds many advantages due to the vast amount of molecular tools and well-characterised pathosystems that are freely accessible for this plant species. This research proposal entails different research lines that focus on various aspects of adaptive immunity in Arabidopsis. Part 1 will exploit naturally occurring variation in adaptive immunity among Arabidopsis accessions. A recombinant inbred population (RIL) from 2 accessions with opposite phenotypes will be screened for early responsiveness to low doses of defence hormones and resistance against pathogens and insects. RILs showing enhanced or repressed priming phenotypes will be analyzed through 'genetical genomics'. This novel technique combines marker-based genotyping with transcription profiling, enabling genetic dissection of the pathways controlling adaptive immunity. Part 2 is focussed on the role of transcription factors and builds on the observation that various priming-inducing signals trigger expression of defence-related TF genes. Through a combination of biochemical and molecular-genetic characterisations, this line of research will reveal how interactions between TFs shape the outcome of the adaptive immune response. Part 3 will explore the cell biology behind adaptive immunity against pathogenic fungi. A forward mutagenesis screen will identify mutants impaired in the priming for cell wall defence. Confocal laser microscopy will reveal the impact of these mutations on cytoskeleton and organelle dynamics. Part 4 will evaluate the ecological value of plant adaptive immunity. Field experiments will be done using the mutants obtained in the other parts of the project. Their ecological performance will be monitored under varying degrees of disease and herbivory pressure.

Publications

10 25 50
 
Description The grant (partially) supported research that uncovered key mechanisms underpinning the onset and long-term maintenance of acquired immunity in plants.
Exploitation Route One of the outcomes of the research supported by this grant is our discovery that the benefits of chemically induced disease resistance (i.e. broad-spectrum disease protection) can by uncoupled from the associated costs on plant growth (Luna et al., 2014; Nature Chem Biol). The outcome of this research has resulted in a follow-up project that is carried out in collaboration with a crop breeding company, in order to translate these findings from model system to crop.

Another key finding that had been supported by this grant is our discovery that high levels of disease can epigenetically alter plants, resulting in transmission of acquired immunuty traits into following generations. This paper was among the first reports showing that plant immunity has a strong epigenetic basis, and stood at the basis off further research projects to investigate the exact epigenetic mechanisms underpinning transgenerational acquired immunity in plants.
Sectors Agriculture, Food and Drink,Chemicals,Environment

URL http://tonlab.wordpress.com/
 
Description 1. Initiation of Research & Development collaboration with crop breeding company (Enza Zaden) to exploit chemically acquired immunity in crops 2. Evidence to support follow-up research into the mechanisms underpinning epigenetic inheritance of acquired plant immunity 3. Evidence to support follow-up research into signalling impacts of maize benzoxazinoids on belowground microbes
First Year Of Impact 2012
Sector Agriculture, Food and Drink,Chemicals,Environment
Impact Types Economic

 
Description no measurable impacts on policy other than citations in scientific journals that may have influenced training of other researchers
Geographic Reach Asia 
Policy Influence Type Influenced training of practitioners or researchers
 
Description ERC consolidator grant; Prime-A-Plant
Amount € 1,307,407 (EUR)
Funding ID 309944 
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 01/2013 
End 12/2017
 
Description Leverhulme Research Leadership Award
Amount £902,625 (GBP)
Funding ID RL-2012-042 
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 05/2013 
End 06/2018
 
Title Arabidposis mutants and over-expression lines of gene encoding receptor of beta-aminobutyric acid 
Description Arabidopsis lines have been created under grant BB/E023959/1 and deposited in the Arabidopsis stock Centre 
Type Of Material Biological samples 
Year Produced 2013 
Provided To Others? Yes  
Impact no impact yet 
 
Title TAIR 
Description Gene identify and function of At4g31180 (IBI1) has been added to The Arabidopsis Information Resource (TAIR) 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact no notable impact yet. 
URL https://www.arabidopsis.org/servlets/Search?type=general&search_action=detail&method=1&show_obsolete...
 
Title 1. Discovery of receptor protein of broad-spectrum defence activator beta-aminobutyric acid (BABA). 2. Discovery that Arabidopsis immune priming can be inherited epigentically 3. Discovery that benzoxazinoids in maize act as defence signals 
Description All knowledge from BB/E023959/1 has been published without application of IP 
IP Reference  
Protection Protection not required
Year Protection Granted
Licensed No
Impact no impact, because nothing has been licenced
 
Description press release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Various press releases about publications that were (partially) funded by BB/E023959/1

Press release about latest paper (Luna et al., 2014; Nat Chem Biol, 10, 450-455) led to research collaboration with Industrial partner, Enza Zaden, which is currently being formalized under a research collaboration agreement with the University of Sheffield.
Year(s) Of Engagement Activity 2012,2014