Rhizosphere by design: breeding to select root traits that physically manipulate soil

Lead Research Organisation: University of Dundee
Department Name: Civil Engineering

Abstract

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Technical Summary

Plant breeding can manipulate root structure, root hair length and exudation properties to physically engineer rhizosphere soil. Little quantitative understanding of the underlying processes exists, so this project will use advanced approaches from engineering science to disentangle the biophysical mechanisms that drive rhizosphere formation. The availability of near isogenic barley and maize lines with differences in root hair length and exudation provides a novel biological resource for this research. Our team is uniquely placed internationally to conduct this research. We were the first to image root hairs in intact soil, allowing modelling of their role in P acquisition. Others in our team found that root hairs aggregate soil at the interface of roots, and the impact increases in less dense soils with lower P. This could help release P and have positive impacts on rhizopshere structure that affects carbon sequestration by roots, but neither study examined the mechanisms in the soil or impacts on water dynamics.

In this project we will isolate and characterise the compounds produced by plant roots that affect surface tension and viscosity at the soil-root interface. The compounds will then be added to soil at a range of concentrations so that the impact on mechanical and hydrological properties can be measured. Using the novel maize and barley lines, we will vary root hair density, length and exudation to examine how these properties influence soil physical properties in rhizosphere samples. In addition, we will measure how the rhizosphere soil physical properties change with age and under different nutrient and physical stresses in glasshouse and field experiments. Non-invasive imaging methods will be used to validate the models and demonstrate how plants progressively change the structure of soil around their roots. The modelling and data generated on rhizosphere formation will identify root trait ideotypes for resource capture and soil sustainability.

Planned Impact

Three strands of research, each lead by separate institutions, are brought together in this proposal: (1) root trait isolation and functioning; (2) rhizosphere biophysical formation; and (3) imaging/numerical modelling of rhizosphere formation and transport properties. By bringing together pioneering research from different areas, the project will have rapid scientific impact, with applications relevant to industry and policy. Crop mapping populations screened for root traits enable our research, which will allow future forward genetics by plant scientists to develop better varieties. Rhizosphere science has an excellent resource of microbiology studies, with our project able to access the vast amount of information already collected to achieve our ultimate goal, a numerical model that can identify ideal root trait ideotypes for sustainable agriculture. By understanding the basic processes of how the rhizosphere forms and functions, we deliver generic approaches that can be applied to investigate future crop traits that allow for decreased resource input, greater abiotic stress tolerance, better water use efficiency, more carbon capture through soil particle aggregation and the physical stabilisation/structural regeneration of soils caused by the action of crop roots. There is a dearth of process based understanding in this area, with much past research focused on qualitative techniques. The numerical models we develop on rhizosphere formation and functioning can also be applied to understanding soil structure away from the plant, so relevant to the larger-scale functioning of terrestrial ecosystems in terms of hydrology, erosion and gas exchange.

Our non-invasive imaging research is world-leading, including recent measurements of root:root hair:soil structure interactions that enabled numerical modelling of phosphorus uptake. Thresholding and image processing algorithms that will be developed by the imaging PDRA are essential to develop this research further, and are applicable to the surge of new plant and soil science research brought about by inexpensive non-invasive imaging technologies. We involve imaging specialists in the project team to ensure the rapid and effective implementation of state-of-the-art techniques.

The plant science industry is challenged with providing farmers with more resource efficient crop varieties. At the farm gate this makes economic sense, but it is also driven by government policies such as GAEC (CAP reforms) and soil protection framework directives. Internationally we address food security, tackling the issue by understanding both plant and soil processes. Soil management practices are changing as a result of policies and socioeconomic factors on farm. By examining root trait performance under different tillage practices, we tackle the challenge of producing varieties suitable for specific environmental conditions. At present, the phenotypic plasticity of root traits is not well understood. Existing elite crop varieties have been predominantly selected in highly loosened and fertilised seedbeds that do not reflect modern on-farm conditions. Our research therefore also delivers to the agricultural engineering industry producing new forms of soil cultivation equipment, who are faced with reticence from the farming community because of perceptions about poorer crop performance. Farmers may just be selecting the wrong crop varieties.

As the rhizosphere is so important to food security and soil sustainability, it deserves greater public awareness. A starting point in this project is engagement through the Aberdeen Biodiversity Centre, who through their own Natural History Museum and links to other museums, provides the skills and contacts for public education. Our root trait lines provide a teaching resource for students to explore rhizosphere formation directly. The graphical output from our imaging research provides visual tools that will capture public interest.

Publications

10 25 50
 
Description This award to the University of Dundee formed only a small part of a much larger project, led by The University of Aberdeen: You are referred to the final key findings report and narrative from Professor PD Hallett (project BB/L026058/1), when the project terminates in summer 2020.
Most significant achievements: This project worked extremely well in terms of collaboration across all four institutions involved (Universities of Aberdeen, Southampton, Dundee, and The James Hutton Institute). Significant scientific achievements included the analysis of the role of different root (barley, maize) and seed (chia) exudates on the physical functioning of the rhizosphere soil, and its potential effects on root uptake and function. Very interestingly the physical nature and influence of the exudates differed substantially and could be both related to chemical composition, and the root-soil uptake dynamics modelled at both pore-, soil core- and field-scales. The role of root hairs was modelled in detail using high-resolution spatial information gathered from two experiments at the Diamond Light Source Synchrotron facility.
We more recently moved the research to field investigations to explore root-hair phenotypes of barley. Two field seasons provided a typically 'wet' and 'dry' year, with interesting contrasts observed. This helped parameterise and verify a field scale model of root hair impacts on phosphorus capture. We are still working on the project, exploring whether root age has an impact on the physical properties of soil at the root-soil interface.
Exploitation Route New techniques have been published, which several groups have already adopted. We have an ultimate goal of providing information to plant breeders to identify root ideotypes that can alter and exploit soil most effectively to enhance yield and soil physical stability.

The research prompted further scientific questions giving rise to a major research proposal between the original collaborators with additional UK Universities, and linking with colleagues in Australia and Germany where a major rhizosphere research initiative is currently underway. Although the initial rhizosphere proposal was unsuccessful, it is our intention to continue applying for funds, probably in smaller consortia.
The role of roots in improving soil properties in relation to both soil carbon storage and the ability of soils to drain rapidly under intense rainfall events is being followed up via EPSRC-funded research at the University of Dundee targeted at adopting a biosystems engineering approach to improved management of soil properties (slope stabilisation, water retention and drainage) adjacent to infrastructure.
Sectors Agriculture

Food and Drink

Environment

 
Description The research is providing new information of benefit to plant breeders and farming groups who sit on the advisory panel. Laboratory and field tests have explored how research and commercial barley genotypes with varying root traits interact with soil physical structure. We benefited from a field experiment running the extremely dry 2018 summer where root hair effects were exacerbated, demonstrating their benefit in capturing nutrients and tolerating abiotic stresses. A field scale model has been developed that can explore the benefits of different root traits in terms of phosphorus capture in a range of environmental conditions. We were unable to host an industry meeting in 2020, so we will disseminate information via a webinar and work with industry to further their efforts to develop crop lines with root traits that can improve resource capture, stress resistance and yield.
First Year Of Impact 2021
Sector Agriculture, Food and Drink,Environment
 
Description Royal Society International Exchange Programme - China
Amount £24,000 (GBP)
Organisation The Royal Society 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2017 
End 03/2019
 
Title Microscale mechanical and hydrological test methods to measure rhizosphere properties 
Description A small scale indenter method was developed to measure micro mechanics and the root-soil interface. This was complemented by a small-scale infiltrometer to measure hydrological properties. 
Type Of Material Biological samples 
Year Produced 2018 
Provided To Others? Yes  
Impact Capability to quantify mechanical and hydrological properties at rhizosphere scale. Will be used for research upcoming in the project. 
URL https://dl.sciencesocieties.org/publications/vzj/abstracts/17/1/170083?noSSO=1
 
Description Assessing the Performance of Grass and Soil in Resisting Erosion - Phase 1 project with CH2M and Environment Agency 
Organisation CH2M HILL
Country United States 
Sector Private 
PI Contribution We are working with CH2M (Project Partner), having been invited by them to tender as subcontractors to this Environment Agency Phase 1 project, conerning the role of grass vegetation in resisting soil erosion of flood embankments.
Collaborator Contribution Working jointly to deliver recommendations for further measurement/monitoring of grassed flood embankments, in view of literature review in progress.
Impact Collaboration has just started.
Start Year 2017
 
Description Contribution of Root Hairs, Mycorrhizae and Bacteria to Organic P Use by Crops 
Organisation China Agricultural University (CAU)
Country China 
Sector Academic/University 
PI Contribution We provide plant genetic materials and experimental know-how developed in existing projects
Collaborator Contribution The CAU partners bring expertise in stable-isotope probing methods to isolate the impact of root exudates on specific rhizosphere microbes.
Impact Three papers published and several in development.
Start Year 2017
 
Description Agricultural diversification in the Highlands of Borneo 
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 I presented work on roots for sustainability at the workshop in Sarawak
Year(s) Of Engagement Activity 2018
 
Description Barley Genotypes - Uses in rhizosphere research 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation at project meeting at BOKU in Austria
Year(s) Of Engagement Activity 2019
 
Description Conference Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Gave Talk ""Understanding the Rhizosheath: Opportunities for Manipulating the Soil Root Interface" at the Plant Biology Europe Conference in Copenhagen, Denmark, approximately 500 people attended the talk.
Year(s) Of Engagement Activity 2018
 
Description Ecosystems and Land Use Stakeholders Engagement Group Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Policymakers/politicians
Results and Impact A stakeholder event for Scottish Government Policy Makers was held in Edinburgh to brief on the latest advances in root biology.
Year(s) Of Engagement Activity 2017
 
Description Friends of University of Dundee Botanic Gardens talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Talk to Friends of the University of Dundee Botanic Garden, and interested members of the general public, concerning Plants and Engineering.
Title: Carbon-friendly engineering of soil with plants.
Location: University of Dundee Botanic Gardens,
Date: 7 September 2018, Dundee.
Year(s) Of Engagement Activity 2018
URL https://www.dundee.ac.uk/botanic/news/2018/article/plants-and-engineering-with-dr-neil-paterson-and-...
 
Description Genotypic variation in the formation of rhizosheath and implications for rhizosphere processes 
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 Presented research at a workshop on Rhizosheath in Lancaster
Year(s) Of Engagement Activity 2017
 
Description Genotypic variation in the formation of rhizosheath and implications for rhizosphere processes 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A lecture to China Agricultural University was given which was webcast to over 2500 viewers
Year(s) Of Engagement Activity 2019
 
Description Genotypic variation in the formation of rhizosheath and implications for rhizosphere processes 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Seminar given at CAAS Xinxiang, China
Year(s) Of Engagement Activity 2019
 
Description Implications of interactions between roots and soil for the formation and function of the rhizosphere 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Keynote Lecture at the BonaRes Annual Meeting, Leipzig Germany. BonaRes is a agglomeration of funded projects on soil in Germany funded by Federal Ministry of Education and Research
Year(s) Of Engagement Activity 2020
 
Description Inaugural talk to public audience at University of Dundee "Discovery Days" event 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Approx 200 audience (combined general public, students and academics) attended, sparking considerable discussion and interest.
Year(s) Of Engagement Activity 2018
URL https://www.dundee.ac.uk/media/dundeewebsite/revealingresearch/documents/2018-Discovery-Days-Program...
 
Description International Society of Root Research Medal Lecture 2017 
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 The ISRR2017 medal lecture invites an eminent scientist who explores root-soil interactions to Dundee to present a lecture, preceded by talks and poster sessions by predominantly early career researchers. This year the invited speaker was Prof Michelle Watt from Juelich.
Year(s) Of Engagement Activity 2017
URL http://www.hutton.ac.uk/events/root-rhizosphere-workshop-and-2017-isrr-dundee-medal-lecture-root-res...
 
Description Invited participation in 25th New Phytologist Workshop (at Sommieres, France) on root traits as predictors of plant-soil functions 
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 Approximately 20 international scientists (mainly Europe and USA) invited to the 25th New Phytologist Workshop looking at functional interactions between root ecological traits and soil/ecosystem functions. A special topic chosen at the meeting was to focus on soil stabilisation as an important root trait function, and Alexia Stokes and helped to lead a session on this topic.
Year(s) Of Engagement Activity 2019
URL https://www.newphytologist.org/workshops/25
 
Description Invited presentation at Symposium, Juelich, 9th Nov 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presentation entitled "Root growth and function in relation to soil strength, structure, and water".
Year(s) Of Engagement Activity 2015
 
Description NERC Planet Earth Article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Article in the NERC Planet Earth magazine, written by journalist Julia Horton. This covered a range of projects conducted by University of Aberdeen scientists on tropical agriculture. The work draws on both our direct research in tropical countries and strategic research on plant-soil interactions, so it cuts across P. Hallett's funding portfolio.
Year(s) Of Engagement Activity 2017
URL http://www.nerc.ac.uk/planetearth/stories/1879/
 
Description NERC UnEarthed 
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 NERC UnEarthed was a large event that attracted over 3000 people. There were two days dedicated to school visits and 2 days when there was free entry to the general public. During our free interactive showcase - UnEarthed - at Dynamic Earth, Edinburgh (17-19 November), families and adults could explore the tools used to make science happen and see the extraordinary work of our scientists. Our exhibit focussed on a range of research projects in tropical ecosystems, specifically on the impacts of agriculture and strategies that could be taken to minimize environmental impacts. The text we used to attract visitors was: Emerging from a Scottish forest you stumble across an orangutan in her nest, with drone footage of her natural habitat. What can this have to do with Scotland? Your food choices affect her habitat, other tropical regions, and the livelihoods of local people. A grocery basket will show you how much of what you eat is tropical. Guess the water used and greenhouse gases emitted producing this food, and then measure it yourself with a gas meter and carbon calculator.

Our research is finding solutions to make this food more sustainable and to protect the livelihoods of people living in vulnerable tropical regions. The most important tropical food is rice. You will see how rice can be selected to grow better with less water by reaching deeper soil with its roots. The other major solution is improving tropical soils. By adding carbon, we will show how they can be restored. Our man dressed as an orangutan was a highlight with kids.
Year(s) Of Engagement Activity 2017
URL http://www.nerc.ac.uk/latest/events/archive/unearthed/
 
Description New crops and cropping systems for a more sustainable future 
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 I presented a seminar at a workshop on New Crops for Agricultural Sustainability at Crops For the Future in Malaysia
Year(s) Of Engagement Activity 2018
 
Description One day meeting on root research, May 2015 inc. First ISRR Medal Lecture 
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 One day workshop on root research, variety of poster and speaker presentations. Audience primarily Regional (Scotland), but with invited speaker from US as medal lecture recipient.
Year(s) Of Engagement Activity 2015
 
Description Platforms to test and demonstrate sustainable soil management: integration of major UK field experiments. 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact An article was written and distributed by the AHDB Newsletter and Website to highlight the impact of soil tillage on the soil physical, biological and chemical characteristics and impact on root growth.
Year(s) Of Engagement Activity 2017
 
Description Presentation for Interdisciplinary Plant Group (University of Missouri, Columbia USA) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited presentation to approx 200 participants of 34th Annual IPG meeting at University of Missouri, Columbia concerning biophysics of root-soil interactions.
Year(s) Of Engagement Activity 2017
URL https://ipg.missouri.edu/feature-stories/34thAnnu_07012017.cfm
 
Description Presentation to International Barley Hub 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Gave talk at the International Balrey Hub aways days in Birnam, UK "Rhizosphere by Design: Understanding and manipulating the barley rhizosphere"
Year(s) Of Engagement Activity 2019
 
Description Root-soil/slope Workshop and ISRR Medal Lecture in Root Research (2016) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Meeting on root-slope interactions, designed to engage with both practitioners (including members of our EPSRC Project Advisory Group), postgraduate students, and researchers.
Year(s) Of Engagement Activity 2016
URL https://roots-dundee.eventbrite.com
 
Description Roots and Rhizospheres for Global Sustainability 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Keynote Lecture at the German Plant Nutrition Society Annual Meeting, Berlin, Germany
Year(s) Of Engagement Activity 2019
 
Description University of Southampton 1 day meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Spoken prsentation entitled "Understanding root growth and function in relation to predicting water uptake from field soil", at 1 day workshop hosted by Southampton University.
Year(s) Of Engagement Activity 2015
 
Description Using plants to manage for sustainability 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Presentation at Sustainable Land Use Stakeholder event
Year(s) Of Engagement Activity 2019
 
Description Workshop on grass reinforcement of floodbanks 
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 Stakeholder meeting with approx 40 attendees to discuss problems of grass erosion on floodbanks. Purpose was to refine and develop business case options for potential project with Environment Agency on improving the use of grass on floodbanks in the UK.
Year(s) Of Engagement Activity 2018
URL http://evidence.environment-agency.gov.uk/FCERM/en/Default/FCRM/Project.aspx?ProjectID=A4D87116-F4D3...