Stomatal-based systems analysis of water use efficiency

Lead Research Organisation: University of Essex
Department Name: Biological Sciences

Abstract

Stomata are pores that provide for gaseous exchange across the impermeable cuticle of plant leaves. They open and close to balance the requirement for CO2 entry for photosynthesis against the need to reduce the transpiration of water vapour and prevent leaf drying. Stomatal transpiration is at the centre of a crisis in water availability and crop production that is expected to unfold over the next 20-30 years: globally, agricultural water usage has increased 6-fold in the past 100 years, twice as fast as the human population, and is projected to double again before 2030. Thus stomata represent an important target for breeders interested in manipulating crop performance. Stomatal movements are driven by solute transport - and consequent uptake/loss of water - across the cell membrane of the guard cells which surround the stomatal pore. Significantly, stomatal responses are slow compared to photosynthesis in the face of environmental fluctuations, especially of light. Improving water use efficiency (=amount of carbon fixed in photosynthesis/amount of water transpired) should be possible, without a cost to carbon assimilated in photosynthesis, if the speed of stomatal responses, especially to light, can be enhanced. However, the complexity of guard cell transport and its coupling to gas exchange and transpiration has presented a formidable barrier to systematic reverse-engineering aimed at enhancing stomatal responses through genetic manipulation and other means.

Quantitative systems analysis offers an effective approach in silico to exploring the link between microscopic gene function and the macroscopic characteristics of assimilation and transpiration. As a first step to bridging this gap in understanding, we developed previously the OnGuard software for quantitative dynamic modelling of the guard cell. OnGuard models build explicitly on the wealth of molecular, biophysical and kinetic knowledge for guard cell transport and metabolism that drive stomatal movement; they accommodate stomata of different plant species, over the full range of conditions studied in the laboratory to date; and they have been shown to incorporate the real predictive power needed to guide experiments at the cellular and physiological levels that start with molecular manipulations in silico. The next major step towards establishing in silico strategies for crop design, based on our deep knowledge of stomatal guard cells, will be to establish and validate this computational link to incorporate carbon assimilation and water use efficiency at leaf and whole-plant levels.

We propose now to develop such a strategy in models of the leaf, and scaling to the crop in the field, that capture CO2 uptake and transpiration. We will build the next-generation OnGuard models that incorporate CO2 uptake and transpiration, and we will incorporate computational statistical methods to accelerate model construction. Most important, the models will provide the essential micro-macro link to connect molecular function with physiological traits of the whole plant in water use and photosynthetic carbon assimilation and will enable scaling to the crop in the field. We will test this second generation of OnGuard models and validate their outputs to examine the longstanding hypothesis that significant erosion in the efficiency of water use by plants arises because of the mismatch in dynamic environmental responses between stomata and photosynthesis. Additionally, we will explore the connection of these traits with oscillations known to occur in stomatal aperture and in the signalling events (e.g. cytosolic-free [Ca2+]) previously documented at the cellular level in single guard cells. All studies will focus on the crop plant Vicia for which there is much data at the single-cell and whole-leaf levels, and on Arabidopsis for which we have mutants with well-defined effects on stomatal kinetics.

Technical Summary

We will incorporate transpiration and carbon fixation explicitly within the OnGuard software, and will test, by in silico modelling and experimental validation, the hypothesis that significant erosion in the efficiency of water use by plants arises because of the mismatch in environmental responses between stomata and photosynthesis. These studies will explore also the connection to oscillations known to occur in stomatal aperture and in the signalling events (e.g. cytosolic-free [Ca2+]) previously documented at the cellular level in single guard cells and reproduced in the first-generation OnGuard models. The modelling and experimental methods proposed are independent, but their combination gives added value to both. Model development will incorporate recent advances in Bayesian inference to enable fast, automated searching for computational solutions. These are proven methods and naturally compute the confidences in model predictions and their relation to observed data. Bayesian methods also address questions such as 'Which parameters are critical to defining a specific set of behaviours?', questions that are important in directing model development. The experimental work will build on methods at the research forefront in analysing water use efficiency in real time from single plants and in scaling for data capture in the field by eddy flux (covariance) and stable isotope discrimination analysis. Experiments will assess stomatal response to light, humidity and CO2 to extract stomatal kinetics and their association with oscillations in transpiration and carbon assimilation. We will use these data to parameterise models and to test the micro-macro link of the models in predicting transpiration and water use efficiency. Thus, we fully expect new and exciting insights into the behaviour of stomata in the leaf and crop canopy, much as our previous modelling efforts provided hitherto unexpected insights into the physiology of the isolated guard cell.

Planned Impact

This proposal is for fundamental research developing new concepts at the core of ideas emerging within the international plant and systems biology communities. The research will stimulate thinking around strategies for systems modelling, especially in relation to membrane transport, plant growth, development and pathology, and it should facilitate in silico methodologies for approaching crop engineering. Thus, the research is expected to benefit fundamental researchers as well as agriculture and industry through conceptual developments as well as the introduction of new computational technologies for the analysis of plant water use efficiency and productivity. The research will feed into higher education training programmes through capacity building at the postgraduate and postdoctoral levels. Additional impact is proposed through public displays and the development of teaching resources building on the background work for this proposal. Finally the research will help guide future efforts in applications to agricultural/industrial systems. The applicants have established links with industrial/technology transfer partners and research institutes to take advantage of these developments. Further details of these, and additional impacts will be found in Part 1 of the Case for Support and in the attached Impact Pathways.
 
Description We have shown that the speed of stomatal response influence photosynthesis and water use efficiency and that this is influence by both anatomy and function of stomata. These findings could provide novel tool for incorporation into breeding programmes to improve water use efficiency. This has also provide further fundamental understanding on the way stomata function which will be vital to on going research.
Exploitation Route The finding of this work has been taken up by many other research labs demonstrated by the number of recent publications that have recently been published that investigate the speed of stomatal behaviour to improve plant performance in some way. It also provide targets for potential manipulation for these processes.
Sectors Agriculture, Food and Drink,Environment

URL https://www.tlawsonlab.co.uk/projects.html
 
Description Agritech Event (Essex) to show case research activities to the industry 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact To showcase and describe research funding at Essex as well as our expertise and capabilities for interacting with the agriculture sector in order to facilitate collaborative research across the faculty and industry.
Year(s) Of Engagement Activity 2018
URL https://www.agritech-east.co.uk/agri-tech-member/university-of-essex/#
 
Description Agritech Week event Essex 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact University of Essex Agritech event.
The event show cased research from Biological Sciences, including the expertise for the Lawson lab. It included presentations, lab-tours and workshop o see and discuss latest developments that are being applied in agricultural sector including:
• Drones
• Image analysis
• Measurement of plant performance
• Stress and disease monitoring
Year(s) Of Engagement Activity 2017,2018
 
Description Chairing a session at the Annual SEB meeting 2019 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Co-chairing an SEB session on Stomata and photosynthetic regulation of water use efficiency at the annual SEB meeting in Seville.
Year(s) Of Engagement Activity 2019
URL http://www.sebiology.org/events/event/seb-seville-2019/programme/plant-biology#stomatal
 
Description Invited seminar speaker Viikki Plant Science Centre 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Seminar describe current research and findings.
Year(s) Of Engagement Activity 2020
URL https://www2.helsinki.fi/en/news/science-news/vips-invited-seminar-december-2020
 
Description Nominated and selected as Co-chair of the GRC CO2 assimilation, USA 2019, and Chair of GRC on the next conference in Italy May 2021 
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 Nominated and selected by peer to be the co-chair for the 2019 conference, and chair for the 2021 GRC conference on CO2 assimilation.

https://www.grc.org/co2-assimilation-in-plants-from-genome-to-biome-conference/2019/
https://www.grc.org/co2-assimilation-in-plants-from-genome-to-biome-conference/2021/
Year(s) Of Engagement Activity 2019
URL https://www.grc.org/co2-assimilation-in-plants-from-genome-to-biome-conference/2019/
 
Description Organisor of Photo-physiology Phenotyping workshop as part of UK PPN 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised a workshop at Essex for the UK Plant Phenotyping next work on Photo-physiology Phenotyping. Sponsorship and attendance by industrial manufactures was sort to support the expenses of international key note speakers in the field.
Year(s) Of Engagement Activity 2013
 
Description Organisor of satellite meeting of the International Photosynthetic congress in Essex 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised Phenotyping for Photosynthesis and productivity meeting. This included raising sponsorship from industry to pay for the event. Keynote speakers who were experts in the field were invited from around the world and their expenses paid for. The meeting show cased the latest technology and developments in the field. A review is currently under revisions that provides an overview of the meeting.
Year(s) Of Engagement Activity 2013,2016
 
Description PEPG workshop 2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The Plant Environmental Physiology Group (PEPG) is a special interest group of the Society for Experimental Biology and the British Ecological Society The Workshop provided a unique opportunity for MSc, PhD students and early career researchers to gain hands-on experience and training in plant ecophysiology techniques from leading scientists and manufacturers. There were 65 student from all around the world. The practical sessions stimulated research discussion and approaches. A poster session also provided the students with the opportunity to interact with established scientist and ask questions of their own research and approaches.
Year(s) Of Engagement Activity 2018
URL https://sites.google.com/prod/view/pepg-workshop
 
Description Plant Ecophysiology group workshop 
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 The PEP group is a special interest group of the SEB and BES. In 2012 Lawson organised a techniques workshop to train the next generation of scientists in some of the key physiological techniques. The week long event comprised of morning lecturer/seminar for expert researchers in the field followed by hands on practical sessions supported by the Industrial manufacturers. Lawson organised the 2014 sessions and is co-organiser of the 2016 and 2018 events.
Year(s) Of Engagement Activity 2012,2014,2016,2018
URL https://sites.google.com/prod/view/drrjwebster/pepg-workshop
 
Description Royal Society Partnership grant which included a 2.5 day visit to local 6th form school (Suffolk one). 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact The Royal Society partnership grant enabled thermal camera to be purchased by the school. Lawson visited the school to present a seminar about the effect of climate change on stomatal behaviour and the use of thermal cameras to monitor plant performance. This was followed by a practical session involving droughted and water watered plants. As part of the assessment the students had to prepare and present posters to explain their findings.
Year(s) Of Engagement Activity 2018
 
Description Royal Society student conference (London RS) December 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact This event followed the Royal Society partnership award that between myself at the University of Essex and Dr Tanja Hofmann One, Ipswich. This event included poster presentation by the school students as well as a display stand to demonstrate the application and benefits of using thermography to assess plant performance.
Year(s) Of Engagement Activity 2018
 
Description Saclay Plant Sciences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Seminar series to present recent work and findings.
Year(s) Of Engagement Activity 2020
URL https://www6.inrae.fr/saclay-plant-sciences_eng/Events/Online-SPS-Seminars/Tracy-Lawson-19-10-2020
 
Description School Seminar (Bristol University) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Lunch time seminar showcase research activities and finding based on funded research within the lab.
Year(s) Of Engagement Activity 2018
 
Description School Seminar (Glasgow University) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Lunch time seminar showcase research activities and finding based on funded research within the lab.
Year(s) Of Engagement Activity 2018
 
Description Seminar speaker for the 1st Brazilian photosynthesis meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Research seminar to share data and findings
Year(s) Of Engagement Activity 2020
URL https://www.even3.com.br/brsymphotosynthesis20/
 
Description Speaker at the PEPg workshop (Lisbon) 2018 
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 The Plant Environmental Physiology Group (PEPG) is a special interest group of the Society for Experimental Biology and the British Ecological Society The Workshop provided a unique opportunity for MSc, PhD students and early career researchers to gain hands-on experience and training in plant ecophysiology techniques from leading scientists and manufacturers. There were 65 student from all around the world. The practical sessions stimulated research discussion and approaches. A poster session also provided the students with the opportunity to interact with established scientist and ask questions of their own research and approaches.
Year(s) Of Engagement Activity 2018
URL https://sites.google.com/prod/view/pepg-workshop/Home?authuser=0