Coordinated Photoreceptor Engineering for Improved Biomass Production

Lead Research Organisation: University of Glasgow
Department Name: College of Medical, Veterinary, Life Sci

Abstract

A key challenge for plant biologists has been to increase plant yield by altering photosynthetic productivity to secure food, energy and environmental sustainability. Phototropin receptor kinases (phot1 and phot2) play an important role in this regard by coordinating multiple light-capturing processes. These include phototropism, chloroplast movements, leaf positioning, leaf expansion and stomatal opening all of which influence a plant's photosynthetic competence by improving the efficiency of light capture, reducing photodamage, and regulating gas exchange between leaves and the atmosphere. However, little effort has been made to target these pathways for improving biomass production.

We have recently shown that targeted engineering can be used successfully to modify the light-sensing properties of the phototropins and increase their sensitivity to light. Plants with these engineered photoreceptors exhibit more rapid and robust chloroplast movement responses and improved leaf positioning and expansion, leading to over 2-fold increases biomass accumulation under light-limiting conditions. These findings demonstrate the feasibility of engineering photoreceptors for improved plant growth and offer additional opportunities for enhancing plant yield through increases in photosynthetic competence.

This proposal capitalises on these findings and will use a combinatorial protein engineering strategy to better synchronise the actions of the phototropins more effectively over a wider range of light conditions without causing detrimental high-light stress. Design principles for better synchronisation between phototropin receptors will be established first in Arabidopsis and extended to crops using barley as a model. Thus, a major outcome of this interlinked effort will be to establish a structural and functional blueprint for constructing engineered photoreceptors that will provide a non-transgenic, genome editing-based approach to coordinate stepwise enhancements in photosynthetic performance with an aim to increasing crop yield.

This work will concurrently generate new photoreceptor components with tailored photochemical properties that will have utility in generating synthetic protein-based switches designed to regulate target cellular activities by light. As our knowledge of phototropin receptor signalling is still far complete, this proposal will also exploit the availability of a novel desensitised photoreceptor mutant background, identified from our phototropin engineering work, to identify new components of phototropin signalling through genetic suppressor screening. Together, the fundamental and applied aspects of this research will expand our understanding of phototropin receptor function and harness the ability to fine tune their action as a bona fide means to modulate yield for agronomic gain.

Technical Summary

The ability to enhance photosynthetic capacity remains a recognised bottleneck to improving plant productivity. Phototropin receptor kinases (phot1 and phot2) play an important role in this regard as they coordinate multiple light-capturing processes that serve to maximise photosynthetic efficiency and promote growth. However, little effort has been made to target these pathways for improved biomass production. Our aims are (1) to optimise photocycle engineering of phot1 and phot2 in Arabidopsis with the goal of better synchronising their activities for gains in photosynthetic performance over a wider range of light conditions (2) apply these design principles to barley (Hordeum vulgrae) to increase productivity (3) establish a structural and functional blueprint for altering phot action that will be widely applicable across plant species and (4) capitalise on our photoreceptor engineering progress by using a novel, desensitised phot mutant background for genetic suppressor screening to identify new signalling components. This proposal integrates both fundamental and applied research that will expand our understanding of phototropin receptor kinase signalling and harness key optogenetic principles (tuning optical sensitivity for gain of function) to establish photoreceptor engineering as a bona fide means to modulate yield for agronomic gain. It builds on our recent success with improving biomass production in Arabidopsis by targeting phototropin receptors for optogenetic manipulation. The proposal draws on established methodologies to expand the array of phototropin variants with altered photochemical properties and identify the most promising of these prior to their use in Arabidopsis and barley. Given the high degree of sequence conservation between higher plant phototropins, the design principles established here should extend to other agronomically important plant species and further expand the array of phototropin-based modules for optogenetic applications.

Planned Impact

This proposal combines practical and fundamental research that is central to concepts emerging from the fields of plant photobiology and optogenetics. The research will stimulate new thinking around ways to improve crop yield and offers new strategies to manipulate plant biomass through alterations in photosynthetic performance. The research therefore has potential to create a new engineering framework for crop improvement that could, in the long-term, benefit farmers, consumers and the environment and contribute to the economic competitiveness of the UK. Commercial organisations interested in implementing new approaches to manipulate plant growth, particularly by altering processes associated with regulating photosynthetic efficiency will also benefit in the longer term. Likewise, these organisations together with fundamental researcher will benefit from the design principles for fine tuning the action of LOV-based optogenetic tools. Additional impact is proposed through summer studentships to develop and implement outreach resources designed to engage the general public and school pupils in key concepts of photobiology, plant science and sustainability. Likewise, the staff assigned to the project will obtain knowledge and expertise that can be applied in related research fields or more widely in the commercial or public sectors. Career progression and training of the staff will also benefit directly from the collaborative and inter-disciplinary nature of the project. Hence, the research will feed directly into higher education training programmes. Finally, the research will contribute to UK competitiveness and quality of life through agro-industrial applications. The PI and Co-Is have established links with industrial/technology transfer partners and research institutes to take advantage of development arising from the research.
 
Description This work has led to a new understanding of how light controls the growth and development of plants. It has uncovered new molecular information on how photoreceptors located within a plant cell, can switch on cellular process to establish important light capturing responses, including phototropism, leaf positioning and chloroplast movement, all of which optimise photosynthetic productivity and growth. Our findings provide new information on the how phototropin photoreceptors attach to the plasma membrane and how their spatiotemporal dynamics, oligomeric status change upon light activation. More importantly, we have made important advances in understanding how these receptor proteins initiate specific cellular signalling pathways from the plasma membrane by directly phosphorylating members of the NPH3/RPT2-like (NRL) protein family. Our establishment a of a new means to identify phototropin kinase substrates (kinase gatekeeper engineering) has been instrumental in moving this field forward.
Exploitation Route The outcomes have provided key progress in address fundamental gaps in our knowledge of how phototropin blue light receptors initiate signalling from the plasma membrane in plants. In particular, this progress will be harnessed by researchers in the field to further investigate the biochemical function and mode of action of NRL proteins in plants.
Sectors Agriculture

Food and Drink

Construction

Education

 
Description At present, our advances in engineering photoreceptor function has attracted interested from Bayer Crop Science. This interest is at a very early stage but something that we will pursue as progress continues.
First Year Of Impact 2018
Sector Agriculture, Food and Drink
 
Title BLINK1 
Description Light regulated potassium channel that has potential in neural silencing. Now demonstrated utility in plants (Science paper pending). Patent has been filed in collaboration with PBL. US patent application 17/431,984; US patent grant 11,542,518. 
Type Of Material Technology assay or reagent 
Year Produced 2015 
Provided To Others? Yes  
Impact Published in Science and awaiting further examination of its utility for optogenetics. 
 
Title GORK Patent 
Description Engineered K+ channel for manipulating plant physiological responses using blue light. Patent Application No. PCT/EP2023/053078 - PBL Ref: 20.665 
Type Of Material Technology assay or reagent 
Year Produced 2021 
Provided To Others? No  
Impact No impacts as yet as still to be published. 
 
Description BLINK Patent 
Organisation Plant Bioscience Limited Technology
Country United Kingdom 
Sector Private 
PI Contribution Data that has now secured a patent filing.
Collaborator Contribution Patent filing.
Impact Patent filed.
Start Year 2019
 
Description John Innes Centre 
Organisation John Innes Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Work on barely is being carried out in collaboration with Wendy Harwood at JIC.
Collaborator Contribution JIC will perform gene editing in barely to introduce point mutations into phototropin blue light receptors that can modulate their photosensitivity.
Impact Work with barley will commence later this year.
Start Year 2021
 
Description Justyna Labuz 
Organisation Jagiellonian University
Country Poland 
Sector Academic/University 
PI Contribution We have successfully engineered the activity of phototropin receptors to modulate plant growth.
Collaborator Contribution Justyna Labuz has characterised chloroplast movement responses.
Impact A manuscript based on our work has been submitted to PNAS.
Start Year 2017
 
Description Matt Jones 
Organisation University of Essex
Department School of Biological Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution Collaborative research on engineered photoreceptors.
Collaborator Contribution Collaborative research on engineered photoreceptors.
Impact Initial data obtained and studies being extended to contribute to publication.
Start Year 2017
 
Description NMR 
Organisation Southern Methodist University
Country United States 
Sector Academic/University 
PI Contribution Collaborative work using NMR spectroscopy for protein structure.
Collaborator Contribution Collaborative work using NMR spectroscopy for protein structure. Hosted visiting PhD student.
Impact New data that should contribute to publication.
Start Year 2016
 
Description Phosphoproteomics 
Organisation University of Dundee
Country United Kingdom 
Sector Academic/University 
PI Contribution Christie and Lamont are collaborating to identify phosphorylation control of higher plant phototropism.
Collaborator Contribution Christie is leading the research and Lamont is providing expertise and facilities to characterise phosphorylation events associated with this process.
Impact Research published in Mol. Plant 1, 178-194 and in several review articles. Data has been presented at numerous international scientific conferences.
Start Year 2006
 
Description Preliminary discussions with Bayer 
Organisation Bayer
Department Bayer CropScience Ltd
Country United Kingdom 
Sector Private 
PI Contribution Initial discussions with Bayer have been made on how they could harness the approach we are taking to manipulate photosynthetic productivity.
Collaborator Contribution Very much an open dialogue at present until we translate our findings to a model crop.
Impact None yet.
Start Year 2022
 
Description Host to school visit 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Hosted school pupils for 1 week from Kelvinside Academy for them to learn and appreciate plant science research.
Year(s) Of Engagement Activity 2023,2024
 
Description Invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Plenary speaker, Young Researchers Symposium on Plant Photobiology, Online Event. Provided a historical overview of my research, career and discussed professional development, career plans with postgraduate students.
Year(s) Of Engagement Activity 2022
 
Description New Phytologist Workshop: introducing Transformative Plant Biotechnology 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Audience comprised of early career researchers and the event focussed on discussing the key challenges facing plant biotechnology, commercialisation of approaches as well as covering key advances in the field.
Year(s) Of Engagement Activity 2023