Data Intensive Modelling of the Rhizosphere Processes

Project Information

DIMR

Grant agreement ID: 646809

DOI

10.3030/646809

Project closed

EC signature date 7 April 2015

Start date 1 September 2015

End date 31 August 2022

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 996 246,00

EU contribution

€ 1 996 246,00

Coordinated by

UNIVERSITY OF SOUTHAMPTON
United Kingdom

Periodic Reporting for period 5 - DIMR (Data Intensive Modelling of the Rhizosphere Processes)

Reporting period: 2021-09-01 to 2022-08-31

Summary of the context and overall objectives of the project

We rely on soil to support the crops on which we depend. Less obviously we also rely on soil for a host of 'free services' from
which we benefit. For example, soil buffers the hydrological system greatly reducing the risk of flooding after heavy rain; soil
contains very large quantities of carbon, which would otherwise be released into the atmosphere where it would contribute to
climate change. Given its importance it is not surprising that soil, especially its interaction with plant roots, has been a focus
of many researchers. However the complex and opaque nature of soil has always made it a difficult medium to study.
In this ERC research program I will develop a state of the art image based model of the physical and chemical properties of
soil and soil-root interactions, i.e. a quantitative, model of the rhizosphere based on fundamental scientific laws.
This will be realised by a combination of innovative, data rich fusion of structural and chemical imaging methods, integration
of experimental efforts to both support and challenge modelling capabilities at the scale of underpinning bio-physical
processes, and application of mathematically sound homogenisation/scale-up techniques to translate knowledge from
rhizosphere to field scale. The specific science questions I will address with these techniques are: (1) how does the soil
around the root, the rhizosphere, function and influence the soil ecosystems at multiple scales, (2) what is the role of rootsoil
interface micro morphology and mycorrhizae on plant nutrient uptake, (3) what is the effect of plant exuded mucilage on
the soil morphology, mechanics and resulting field and ecosystem scale soil function and (4) how to translate this knowledge
from the single root scale to root system, field and ecosystem scale in order to predict how the climate change, different soil
management strategies and plant breeding will influence the soil fertility.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

This project focuses on investigating how plants and soil interact in order to gain a better understanding of the fundamental processes which control this system. With this improved understanding scientist will then able to provide advice to agronomists, farmers, managers etc. how to better manage crops, soils and natural ecosystems. In particular, we are using correlative structural imaging and chemical elemental mapping to build new models of plant-soil interaction. These new models will enable in silico scenario testing of different soil and crop management scenarios.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The progress beyond the state of the art can be summarised by the following 3 statements related to the recently published papers.

1. Cooper et al (2017) “Fluid flow in porous media using image based modelling to parametrise Richards’ equation” in Proceedings of The Royal Society A. This is the first paper in the world to show how Richards’ equation could be parameterised from the soil underlying observed geometry. This is important for the two reasons: (a) the conventional experimental measurements to properly parameterise Richards’ equation are very time consuming (3+ montshs), however our computational image based approach is much faster (couple of weeks depending on soil and availability of the imaging equipment) thus enabling the possibility of high throughput comparison of different soils and guiding of soil amendments based on in silico computations. (b) conventional measurements cannot be conducted on the rhizosphere (ie region of soil influenced by roots) scale since this region is very small (<=1mm) and traditional methods could not be used since stable structural and biological sampling is not possible, and hence the non-invasive image based modelling is the only way to address this. As an evidence of the importance of this paper one reviewer wrote that “… this is the biggest breakthrough since 1953 when Lorenzo Richards published his thesis” and whilst the paper was published on Nov 22nd 2017, during the month of Nov 2017 (ie in 9 days) it was read by 200+ times and as of March 1st 2018 it had been read by over 700 times.
2. As the second “paper” I want to name two interlinked papers, Keyes et al (2017) and (2016) that dealt with imaging plant root growth in the soil. The paper published in 2016 dealt with single entire root scale imaging of root growth in 4D (3D+time) and estimating how the soil strains using the image analysis tools. The paper published in 2017 did the same at the high resolution near the individual root tip thus for the first time showing how to observe the micromechanics of root growth in real soil. The reason why these papers are important is that they set up for the first time an experimental and image analysis protocol to enable the time-lapse observation of root architecture. Most of the previous imaging has not been able to image root growth at the timescales where one could observe grain movement, soil pore water movement etc. However, this is important if one wants to (a) have fundamental understanding of how plant roots grow in soil and (b) how to modify the roots or soil amendments to enhance, or in impede, root growth and function in the soil. This knowledge will be useful for situations where we would like to use plants or grow crops in soils which are prone to instability, landsildes, and flooding.
3. As the third paper I would like to discusse Van Veelen et al (2019) which combines correlatively structural observations of soil mechanics using X-ray CT and elemental mapping using XRF and XANES. As part of this paper we introduce the concpt of root microbial incubator as we show for the first time that all/most microbially mediated soil chemcial transformations are primarily constrained to the zone around the root that is phyiscally sealed off from the bulk soil. This zone seems to also be influenced by the presence of root hairs and thus potentially offers a way for manipulating it if needed.
3. As the final paper I am naming our latest paper on mycorrhizae-plant interaction in soil by Keyes et al 2022. In this paper we developed an assay for imaging mycorrhizae morphology in soil using synchrotron beamlines and correlated this structural information to chemical information obtained by XRF/XANES imaging on different synchrotron beamlines. All this structural information was correlated with chemical information and integrated with mathematical modelling to predict the role of mycorrhizae on plant P uptake. Whilst, arguably, this paper raises more questions than it answers it has demonstrated the power of this new technology and now stimulates worldwide more such integrative work.

The experimental aspects of the study were clearly delayed by COVID-19 induced societal and lab lockdowns, but we achieved all that we set out to achive. Most notably, our work on monitoring and modelling P release from fertiliser pellet (Petroselli et al 2021) won Chiara Petroselli a first/top prize in the International Fertiliser Society 2020 Brian Chambers Award for Early Career Achievements in Crop Nutrition. It was an international competition with 10 finalists from across all continents. Not only did my ERC postdoc Chiara Petroselli win the top award, but another postdoc Dan McKay Fletcher shared one of the two runner up prizes, and the third postdoc Siul Ruiz was one of the ten finalists.

Image of SXRCT of fungi in the soil.

Root scavenging P pellet, root — yellow, P — green and S — blue

Citrate concentrations on 2D planes for a young wheat root system. Citrate solution concentration at

Visual comparison of sub-regions of the aligned XCT slice, BSEI and P EDS map for each thin-sec

Comparison of 3D morphological features during drying from a modelled liquid bridge representing pla

Visulization of root P uptake evolution for high/low buffering soils and 3 fertiliser dissolution ra