ez-root-vis: a software pipeline for the rapid analysis ... · (armengaud et al., 2009). for...

36
1 1 EZ-Root-VIS: A Software Pipeline for the Rapid Analysis and Visual Reconstruction of 2 Root System Architecture 3 4 Zaigham Shahzad 1 , Fabian Kellermeier 1 , Emily M. Armstrong 1 , Simon Rogers 2 , Guillaume 5 Lobet 3,4 , Anna Amtmann 1* and Adrian Hills 1* 6 7 1 Institute of Molecular, Cell and Systems Biology, University of Glasgow, G12 8QQ, UK 8 2 School of Computing Science, University of Glasgow, G12 8QQ, UK 9 3 Agrosphäre (IBG-3), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany 10 4 Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, 1348, 11 Belgium 12 13 *Corresponding Authors: 14 Anna Amtmann [email protected], Adrian Hills [email protected] 15 16 Short title: Reconstructing root architecture. 17 18 One-sentence summary: 19 EZ-Root-VIS is a free software package that enables the rapid quantification and visual 20 reconstruction of averaged root system architectures for investigating environment-genotype 21 interactions. 22 23 Author contributions: 24 The EZ-Root-VIS pipeline was conceived by F.K. and A.A., and developed by A.H with 25 input from S.R. and G.L. Root growth rate assays were carried out by F.K. GWAS and 26 genotype-environment interaction studies were designed and performed by Z.S. E.M.A. 27 helped with the development of the software pipeline and tested the most recent versions 28 using experimental data. AA managed the project. Z.S., A.A., and A.H., wrote the paper. 29 30 Funding sources: 31 The work was funded by the BBSRC (BB/N018508/1) and by the Gatsby Charitable Trust 32 (Sainsbury studentship to FK). 33 Plant Physiology Preview. Published on June 12, 2018, as DOI:10.1104/pp.18.00217 Copyright 2018 by the American Society of Plant Biologists www.plantphysiol.org on June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Upload: others

Post on 01-Jun-2020

5 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

1

EZ-Root-VIS: A Software Pipeline for the Rapid Analysis and Visual Reconstruction of 2

Root System Architecture 3

4

Zaigham Shahzad1, Fabian Kellermeier

1, Emily M. Armstrong

1, Simon Rogers

2, Guillaume 5

Lobet3,4

, Anna Amtmann1*

and Adrian Hills1*

6

7

1 Institute of Molecular, Cell and Systems Biology, University of Glasgow, G12 8QQ, UK 8

2 School of Computing Science, University of Glasgow, G12 8QQ, UK 9

3 Agrosphäre (IBG-3), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany 10

4 Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, 1348, 11

Belgium 12

13

*Corresponding Authors: 14

Anna Amtmann [email protected], Adrian Hills [email protected] 15

16

Short title: Reconstructing root architecture. 17

18

One-sentence summary: 19

EZ-Root-VIS is a free software package that enables the rapid quantification and visual 20

reconstruction of averaged root system architectures for investigating environment-genotype 21

interactions. 22

23

Author contributions: 24

The EZ-Root-VIS pipeline was conceived by F.K. and A.A., and developed by A.H with 25

input from S.R. and G.L. Root growth rate assays were carried out by F.K. GWAS and 26

genotype-environment interaction studies were designed and performed by Z.S. E.M.A. 27

helped with the development of the software pipeline and tested the most recent versions 28

using experimental data. AA managed the project. Z.S., A.A., and A.H., wrote the paper. 29

30

Funding sources: 31

The work was funded by the BBSRC (BB/N018508/1) and by the Gatsby Charitable Trust 32

(Sainsbury studentship to FK). 33

Plant Physiology Preview. Published on June 12, 2018, as DOI:10.1104/pp.18.00217

Copyright 2018 by the American Society of Plant Biologists

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 2: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

2

34

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 3: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

3

ABSTRACT 35

If we want to understand how the environment has shaped the appearance and behavior of 36

living creatures we need to compare groups of individuals that differ in genetic make-up and 37

environment experience. For complex phenotypic features, such as body posture or facial 38

expression in humans, comparison is not straightforward because some of the contributing 39

factors cannot easily be quantified or averaged across individuals. Therefore, computational 40

methods are used to reconstruct representative prototypes using a range of algorithms for 41

filling in missing information and calculating means. The same problem applies to the root 42

system architecture (RSA) of plants. Several computer programs are available for extracting 43

numerical data from root images but they usually do not offer customized data analysis or 44

visual reconstruction of RSA. We have developed Root-VIS, a free software tool, which 45

facilitates the determination of means and variance of many different RSA features across 46

user-selected sets of root images. Furthermore, Root-VIS offers several options to generate 47

visual reconstructions of root systems from the averaged data to enable screening and 48

modeling. We have confirmed the suitability of Root-VIS, combined with a new version of 49

EZ-Rhizo, for the rapid characterization of genotype-environment interactions and gene 50

discovery through genome-wide association studies in Arabidopsis (Arabidopsis thaliana). 51

52

INTRODUCTION 53

Roots play a critical role in soil water and nutrient uptake and thus in plant productivity. Root 54

system architecture (RSA) is determined by the relative growth of different parts of the root 55

system as well as frequency of branching and branch angles. RSA is a key determinant of 56

root function and is highly plastic, being controlled by genotype–environment interactions 57

(Yu et al., 2016; Shahzad and Amtmann, 2017; Morris et al. 2017). Optimization of RSA is 58

thus imperative for the improvement of plant resilience, particularly to soil-borne stresses 59

such as soil drought, flooding, nutrient deficiencies, and biotic factors (Julkowska and 60

Testerink, 2015; Lynch, 2015; Rogers and Benfey 2015). Correlation of root morphology 61

with DNA sequence information allows the identification of the genetic loci that underpin 62

root features, for example through mutant screens, quantitative trait locus (QTL) analysis or 63

genome-wide association studies (GWAS). New sequencing technology has vastly increased 64

the amount of available genetic information, and better phenotyping assays are now required 65

to meet the pace of these advancements. Depending on the research question, different 66

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 4: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

4

phenotyping approaches need to be taken, because there is a trade-off between (a) reflecting 67

realistic environments, (b) controlling environmental factors, (c) obtaining precise 68

information on individual parts of the root systems, and (d) throughput. 69

Several platforms to obtain root images from plants grown in soil (field, pots or rhizotrons) 70

are available, together with software to capture and model the overall size and shape of the 71

complex root systems (Lobet et al., 2011; Bucksch et al., 2014; Kalogiros et al., 2016). These 72

studies are complemented by analyses of roots developing on synthetic surfaces, which offer 73

more precise control and manipulation of the root environment. Open source software such as 74

BRAT (Slovak et al., 2014; Satbhai et al., 2017) and RootTrace (Naeem et al., 2011) have 75

been developed to precisely track the early main root growth from scanned images of 76

Arabidopsis thaliana seedlings growing on plates. An intermediate analysis space is occupied 77

by software such as EZ-Rhizo (Armengaud et al., 2009), archiDART (Delory et al. 2016, 78

2018), RootScape (Ristova et al., 2013), and the commercial WinRhizo (Arsenault et al., 79

1995). They have facilitated the quantitative assessment of more advanced root systems of 80

Arabidopsis and other dicot plants, including information on lateral root features such as 81

position, length, density and angle. This information has generated knowledge on branching 82

patterns, rather than just primary root growth or overall shape, and has enabled large-scale 83

phenotyping of Arabidopsis roots to investigate natural variation and responses to multiple 84

environmental cues (Gruber et al., 2013; Kellermeier et al., 2013, 2014; Julkowska et al., 85

2017). 86

With a good range of root image analysis software in place, the next challenge is how to 87

process the acquired numerical data in order to extract biologically meaningful and 88

statistically valid results. Averaging across replicates is easy for some simple RSA traits, 89

such as main root (MR) length and lateral root (LR) number, but it is less straightforward for 90

other traits. For example, how should we calculate the mean LR length if the number of LRs 91

differs between replicate plants? We can either average the length of all laterals in each plant 92

before averaging across plants, or we can average individual LRs across replicates. The latter 93

can be done either by the order of appearance (1st, 2

nd LR etc.) or by their position on the 94

main root (e.g. all LRs within a particular sector of the main root). There is no one ‘correct’ 95

solution to this problem; rather, each of the approaches is more or less suited to answer a 96

specific question. For example, the first average provides a measure of overall growth 97

investment into lateral roots, the second provides information on how individual LRs develop, 98

and the last approach best reflects the root shape. It is therefore important that RSA analysis 99

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 5: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

5

software, in addition to enabling data acquisition, also offers different options for extracting 100

mean root traits and their variance, which can then be used as a numerical input for genetic 101

studies or developmental models. 102

Another challenge is how to visually represent averaged root systems in a manner that clearly 103

and faithfully reflects differences between genotypes or environmental conditions. Current 104

root image analysis software packages rarely include options to visually reconstruct single-105

plant or mean RSAs from the measured data. In publications, the individual averaged RSA 106

traits are usually represented in multiple bar graphs. A picture of one ‘representative’ root 107

system is often included, but considering the variability and complexity of RSA it is unlikely 108

that one individual plant can indeed be representative in all RSA traits. The reader is left with 109

the difficult task of deducing the mean RSA from bar graphs of all individual traits. 110

To address these problems we have developed a new application, Root-VIS, which enables 111

calculation and visual reconstruction of mean RSAs from measured data. We exemplify the 112

possibilities offered by Root-VIS using data acquired with a greatly enhanced version of the 113

previously published EZ-Rhizo program. The combined EZ-Root-VIS pipeline provides an 114

easy procedure to capture RSA features of many individual plants and to visualize averaged 115

RSAs for different genotypes under various environments or at different time points. Root-116

VIS offers a range of choices for how to calculate means and how to visually represent the 117

average root phenotypes. For example, it allows users to calculate means of LR-related traits 118

on a per-plant or a per-branch basis. It provides possibilities to redraw average root 119

architectures from the extracted data or to regenerate root shapes in the form of flag plots, as 120

well as growth-investment or LR length profiles. We have validated the utility of the EZ-121

Root-VIS pipeline for studying root growth dynamics, quantitative genetics, and genotype-122

environment interactions. 123

124

RESULTS 125

Description of the EZ-Root-VIS pipeline 126

The software is a ‘standalone’ implementation, compatible with all Microsoft Windows 127

operating systems from Windows XP (SP-3) onwards, including Vista, Windows 7, 8/8.1 and 128

10 (in ‘Classic Desktop’ mode). Separate versions are available for 32-bit and 64-bit 129

platforms. The installation package includes Root-VIS and the latest version of the EZ-Rhizo 130

program, which has a number of additions and improvements over the original 2009 release 131

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 6: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

6

(Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the 132

standard formats: Windows Bitmap (BMP) files, Graphics Interchange Format (GIF), Joint 133

Photographic Experts Group compressed images (JPEG), Portable Network Graphics (PNG) 134

or Tagged Image File Format (TIFF) files, and at any resolution. The software presents a 135

typical, Windows-style graphical user interface (GUI) (Supplemental Figure 1A) which will 136

be very familiar to users of the Microsoft®

Visual Studio development environment. 137

Extensive (and context-sensitive) on-line help is included with the software (Supplemental 138

Figure 1B). The software also provides numerous, user-selectable options for controlling the 139

content and style of displays, and the parameters used in the reconstruction and averaging 140

algorithms. These are adjustable via a “Settings” property sheet (Supplemental Figure 1C). 141

Figure 1A summarizes the workflow of RSA analysis with the EZ-Root-VIS pipeline. Images 142

of plants grown on agar plates in 2D are usually acquired with flatbed scanners (Figure 1B), 143

but any image capturing device that generates sufficient contrast and resolution is suitable. 144

First, EZ-Rhizo is used to process the images and extract numerical data of RSA features of 145

individual roots (Figure 1C). After image cropping, conversion into black and white and 146

background noise filtering, roots are pixelated, skeletonized, edited and detected as described 147

before (Armengaud et al., 2009). In the new version of EZ-Rhizo, we have included an option 148

to re-define the main root (the original version assumed the longest root path formed the MR 149

and this is also the default setting). The numerical results of the analysis are saved in a user-150

selectable database, which is now in XML format, allowing easy sharing of datasets between 151

the acquisition and analysis modules. Root-VIS then ‘reads’ the database generated by EZ-152

Rhizo and displays the files in a database window (left panel in Supplemental Figure 1A). 153

Prior to averaging RSA data from replicate roots, Root-VIS offers the possibility to draw a 154

visual reconstruction of any individual root in the dataset (Figure 1D), which allows the user 155

to verify the data that were captured by the image acquisition software. 156

At the heart of the Root-VIS software lies the concept of the ‘collection analysis’, in which 157

data extracted from the database are grouped according to the metadata parameters entered 158

during image analysis, including genotype, media type and plant age. Analyses can be carried 159

out with zero, one or two of these parameters being variants. The database structure displayed 160

in the analysis window makes it easy to remove or pool individual samples or groups of 161

samples from the analysis (Supplemental Figure 1B). The averaged root for each group can 162

then be displayed visually using a ‘reconstruction’ algorithm described in more detail in the 163

Methods section. Two types of averaged root systems can be generated: “absolute” and 164

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 7: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

7

“binned” (Figure 1E-F). In the ‘absolute’ mode, lateral roots are averaged according to their 165

order of appearance; in the ‘binned’ mode, the branched zone is divided into sectors (the 166

number of which is equal to the mean number of LRs), and the lengths of LRs in each sector 167

(‘bin’) are averaged. The program also provides an option to visualize the variation between 168

individual replicate roots in ‘alpha blends’ (Figure 1G). Additional visualization options are 169

‘flag plots’ (Figure 1H), which represent the overall density and shape of the root system, and 170

LR profiles (Figure 1I), which represent the size of LRs in different parts of the root system. 171

Flag plots are based on LR angle and LR density as well as the lengths of branched and un-172

branched zones of the MR as depicted in Supplemental Figure 2. For the LR profiles, the MR 173

length is divided into a user-defined number of sections, and for each section LR length is 174

displayed as a rectangle of appropriate size. Each of the display modes has a number of sub-175

options, which the user can select in the ‘Settings’ windows. For example, LR profiles can be 176

chosen to show either the sum length of all LRs (LR size, LRS) or the mean LR length (LRL) 177

in each MR sector. The former provides a measure of total growth investment into a certain 178

part of the root, whereas the latter reflects the local root system width. The different displays 179

are exemplified below using experimental data. We also generated an optional plug-in 180

module, XL-Orate, which allows users to create formatted tables of averaged trait data, 181

including standard errors and number of replicates using Microsoft® Excel (Figure 1J, 182

Supplemental Dataset 1), and to rapidly generate bar charts for any data generated with EZ-183

Rhizo and Root-VIS. The obtained datasets can now be used in a range of downstream 184

studies including growth models, quantitative genetics and breeding. 185

186

EZ-Root-VIS captures root growth dynamics 187

To validate the ability of the EZ-Root-VIS pipeline to capture root system growth, we 188

measured RSA of Arabidopsis Col-0 plants every two days over a period of 4 to 14 days after 189

germination (DAG). Quantitative data for 16 root traits (see Abbreviations) were obtained 190

using EZ-Rhizo. A 3D bar chart generated for three root traits (MRL, LRL, LRD-BZ) (Figure 191

2A) exemplifies the difficulty of visually representing the complexity of RSA changes in bar 192

graphs; several additional graphs would be required to represent the overall RSA. In contrast, 193

the visual root system reconstructions implemented in Root-VIS accommodate all the root 194

traits and represent averaged RSA (either ‘absolute’ or ‘binned’) as a single image (Figure 2B, 195

C). In this example, the display incorporated bends into the MR path to account for the 196

measured difference between MR path length and MR vector length (straightness). The 197

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 8: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

8

program accommodates any surplus of path length over vector length across equally sized 198

bends, which are placed at LR emergence sites in the branched zone and at equal distances 199

along the apical zone (see Methods). However, the user should keep in mind that EZ-Rhizo 200

does not determine the number, size and position of bends, and the displayed bending pattern 201

could look very different from the original images. To avoid over-interpretation of the 202

displayed bending pattern it might be safer to display either path or vector length as a straight 203

line. Therefore, in the ‘Settings’ property sheet, the user can toggle between displaying bends 204

(in the MR and/or LR), or not. 205

Figure 2D shows the superposition of all re-constructed individual roots as alpha blends, 206

reflecting the variation across replicates. A similar darkness of the blends indicated that the 207

variation of RSA between individual plants did not substantially increase with plant age. The 208

flag plots (Figure 2E) show how the root system increases in depth, width and density over 209

time. For this figure, flag plots were produced based on absolute values of MR and LR 210

lengths and angles, and on the slope of the linear regression of average LR lengths at the 211

given LR positions (see Supplemental Figure 2 and Methods). The shade of the flag fill color 212

indicates LR density with darker shades representing higher density. Finally, LRS profiles 213

(Figure 2F) allow the reader to quickly evaluate the growth investment into LRs in different 214

parts of the root. In this case, the MR was divided into four equal sections (quartiles). The 215

profiles show a sharp increase of mean LRS from 8 DAG onwards, especially in the two 216

basal quartiles of the main root. The data underpinning Figure 2, extracted using XL-Orate 217

(Supplemental Dataset 2), provide a convenient input for root growth models. 218

219

EZ-Root-VIS reveals genotype by environment interactions 220

To demonstrate the effectiveness of the pipeline in capturing genotype by environment 221

interactions, RSA data were acquired with EZ-Rhizo from replicate plants of nine 222

Arabidopsis accessions, grown in four nutrient media: control, low phosphate (P, 20 µM), 223

low potassium (K, 10 µM), or combined low PK media (Figure 3, Supplemental Dataset 3; 224

for growth media see Methods). The visual reconstructions (Figure 3) generated by Root-VIS 225

facilitate the rapid identification of interesting responses and RSA ideotypes, while Excel 226

generated bar graphs (Figure 4) depict means and standard errors of the individual traits. As 227

reported before (Chevalier et al., 2003; Reymond et al., 2006; Svistoonoff et al., 2007), the 228

Shahdara accession showed a strong inhibition of MR growth in response to P limitation. An 229

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 9: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

9

even stronger reduction of MR length was found for T1080 despite similar MR length on 230

control media. In most other accessions, e.g. Aitba-2 and Cerv-1, MR growth was not 231

sensitive to P availability, and in the Ber accession, MR growth was even stimulated by 232

decreasing the P supply (Figure 3A, Figure 4A). By contrast, in Ber, Aitba-2 and Cerv-1, low 233

P resulted in a reduction in the LR system size (LRS; measured as total lateral root path 234

length) (Figure 4B), particularly in the basal (upper) quartile of the main root (LRS (0.25), 235

Figure 3A, Figure 4D). Unlike low P, low K decreased MR length in all accessions tested, 236

albeit to varying extents, and caused a decrease of LRS in most accessions (Figure 3A). 237

Exceptions to the latter were Gie-0 and N13, which already had very small LRS in control 238

conditions. 239

The effects of combined P and K limitation were striking and in many cases could not have 240

been predicted from individual deficiency effects. In accessions experiencing MR inhibition 241

under low P (e.g. Shahdara, T1080), combined PK limitation had an additive inhibitory effect, 242

but in several other accessions (Gie-0, Ber, N13, Aitba-2) we recorded a complete or partial 243

reversal of the low K-induced MR inhibition by decreasing P (Figure 4A). In Cerv-1 and 244

Dog-4, MR inhibition by low K was maintained in low PK and dominated over MR 245

insensitivity to low P. In contrast to the genotype-dependent response of MR to single and 246

double deficiency, the LRS of all genotypes was smaller under combined PK limitation than 247

under single deficiencies (Figure 4B). LR density in the branched zone (LRD-BZ) was in 248

most accessions stable across treatments (Figure 4C) with the exception of Ber, N13 and 249

Aitba-2, which showed an increase of LRD-BZ under low K. To separate the effects of LR 250

number and LR length on total LRS, LRL profiles and flag plots were also plotted 251

(Supplemental Figure 3). Figure 4E shows the extracted data from these profiles as bar 252

graphs. 253

The re-constructed average RSAs (Figure 3B) pinpointed additional differences. For example, 254

MR growth was more or less vertical depending on genotype and environment. In control 255

medium, the MR angle (MRA) differed between accessions (Figure 4D), although the 256

direction was always the same (‘positive’, see Methods for sign definition). Under low P, 257

MRA remained similar to control in most accessions, but markedly increased in Ber, N13 and 258

Aitba-2, and decreased in T1080. Under low K, MRAs decreased in all accessions apart from 259

N13. In most accessions the low-K MRA phenotype was reverted back to control or to low-P 260

phenotypes in low PK, with the notable exception of Shahdara. 261

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 10: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

10

In summary, the EZ-Root-VIS pipeline enabled the analysis of complex responses of various 262

root architectural traits to either single or combined nutrient limitations. The averaged visual 263

representations allow the fast identification of nutrient interactions and of accessions that 264

show particularly interesting RSA responses. It is remarkable that the relatively small number 265

of accessions and nutrients tested here already encompass a diverse range of combinatorial 266

phenotypic outputs. 267

268

EZ-Root-VIS enables large scale RSA genetic studies 269

To validate the utility of our pipeline for large-scale quantitative genetic studies, we 270

measured RSA of 147 Arabidopsis accessions with EZ-Rhizo, and determined means of 16 271

root traits with Root-VIS for downstream analyses (Supplemental Dataset 4). Five plants per 272

accession were grown on standard medium, and it took one person 13 hours to analyze all 273

root images obtained at one time point (12 DAG) using the EZ-Root-VIS pipeline. 274

Ten of the analyzed root traits exhibited a normal distribution (Supplemental Figure 4), but 275

several traits showed a positively skewed trait distribution, including for example LR size and 276

number. Correlation analysis revealed a high degree of inter-dependence of the RSA traits 277

(Figure 5A). Only main root angle (MRA) and lateral root angle (LRA) were relatively 278

independent of other RSA traits, although they showed correlation with the size of MR and 279

LRs, respectively. Surprisingly, MR length was not correlated with the LR density over the 280

MR (LRD-MR) but was negatively correlated with LR density over the branched zone (LRD-281

BZ). This observation stresses the importance of determining LR density in the branched 282

zone rather than relating the number of LRs to the entire main root. Interestingly, LR density 283

was also negatively correlated with the length of the basal zone (BsZL). In fact, BsZL was 284

negatively correlated with most LR traits, suggesting that the amount of main root growth 285

before emergence of the first LR is an important determinant of other RSA features. 286

Hierarchical clustering was performed to classify the accessions into groups sharing similar 287

RSA based on 15 RSA architecture traits (LR angle was excluded from this analysis due to 288

some negative values). As shown in Figure 5B, the accessions were assigned into eight 289

clusters (Supplemental Dataset 4). Four clusters contained only one accession (Da(1)-12, 290

Lp2-2, N13 and Kn-0), while the largest cluster contained 73 accessions. Average LRS 291

profiles of the central genotype of each cluster (Figure 5C) indicated different growth 292

investment into MR and LR. Averaged RSA reconstructions revealed differences in MRA. 293

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 11: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

11

For example, the Sanna-2 and Mt-0 groups exhibited more positively skewed MRs than other 294

groups. Thus, when applied to natural variation studies, Root-VIS quickly identifies root 295

traits that are critical determinants of the overall RSA. 296

To test if the data extracted with EZ-Root-VIS can facilitate genetic mapping studies, we 297

performed GWA mapping for 16 root traits using an accelerated mixed model (AMM) 298

implemented in the GWAPP web application (Seren et al., 2012). In total, seven unique 299

locus-specific single nucleotide polymorphisms (SNPs) were found to be associated with 300

various root traits at 5% FDR (Supplemental Dataset 5). Out of these, one (SNP4 6374071) 301

was associated with TRS, LRS and LRS (0.25) (Figure 6A), three were associated with basal 302

zone length (BsZL) and one was associated with lateral root density (LRD-MR). 303

Forty-seven additional SNPs were identified to be associated with root traits with an adjusted 304

threshold of -log10(P) > 5.0 (Supplemental Dataset 5). One of them resembled SNP4 6374071 305

insofar as it showed association with LRS (0.25), LRS and TRS, suggesting a strong 306

contribution of the lateral root size in the basal quartile to the overall root size. We named the 307

two loci Lateral Root Size Locus (LRSL) and General Regulator Factor 1 (GRF1) (Figure 308

6A). LRS designates a 5 kb region that harbors four candidate genes (Supplemental Figure 309

5B). The GRF1 locus was named after the only gene, AT4G09000 (GRF1), present in a 5 kb 310

window around the strongest associated SNPs for this region (Supplemental Figure 5A). 311

Interestingly, GRF1 has been reported to be downregulated during LR emergence (Voß et al., 312

2015), and the expression of one of the candidates in LRSL, AT4G10270, is strongly induced 313

around the time of LR emergence and in emerged LRs (Supplemental Figure 5C-D). We 314

therefore investigated root phenotypes of Col-0 T-DNA insertion mutants for these two genes. 315

Indeed, the LRS profiles showed that knockout mutants of GRF1 or AT4G10270 exhibited 316

reductions in LRS (0.25), LRS and TRS compared to wild-type plants (Figure 6B), and the 317

extracted data confirmed that the differences were statistically significant (Figure 6C). 318

In addition, we characterized the root phenotypes of T-DNA insertion lines of candidate 319

genes underlying 18 other associations (4 significant, 14 between -log10(p) > 5.0 and 320

significant threshold) in the Col-0 or Col-3 backgrounds (Supplemental Dataset 5). In total, 321

for 14 out of the 21 associations, the mutants showed significant phenotypic differences from 322

wild type in root traits for which associations were initially identified, including MR angle, 323

MR length, LRD-BZ, LR number, BsZL, and apical ZL (AZL) (Supplemental Figure 6, 324

Supplemental Dataset 5). Some genes, such as ALF5 and AXR5, were found to contribute to 325

more RSA traits than initially highlighted by the GWAS, suggesting a more general role in 326

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 12: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

12

root growth and development. Data for all RSA traits in all lines are provided in 327

Supplemental Dataset 6. These results confirm that the EZ-Root-VIS pipeline is a useful tool 328

for fast gene discovery by high-throughput RSA phenotyping. 329

330

DISCUSSION 331

Root-VIS is novel for its ability to average RSA traits using several different algorithms and 332

to visually reconstruct the averaged RSA in several manners. During the development of the 333

software, great effort has been made to create an ergonomically efficient user interface, 334

which is a critical factor in determining the software’s ease of use. Both EZ-Rhizo and Root-335

VIS present a Windows-style graphical user interface (GUI) that will be easy to handle for 336

new users. Other features include numerous keyboard accelerators and the option to skip 337

parameter-setting dialogues using the ‘shift’ key, and an “Undo” command to avoid having to 338

restart processing following inadvertent errors. Such features may, at first, seem trivial but, 339

when considering that a typical experiment may involve processing several hundred images 340

per day, they can make an enormous difference to the overall user experience and greatly 341

reduce problems arising from ‘software fatigue’. 342

We have validated our pipeline to capture fairly complex RSA of 12-day-old Arabidopsis 343

plants in multiple contexts, including time series experiments, large scale natural variation 344

and genotype–environment interaction studies. We provide the options to extract means 345

based on order (‘absolute’) or local position of the lateral (‘binned’). It was noted that 346

depending on how much LR number varies between individual plants, the different averaging 347

methods can lead to about 10% variation in means determined for LR-related traits. Such 348

variation can be crucial when handling a large number of genotypes since the phenotypic 349

spectrum across accessions is continuous with relatively small differences between the 350

individual accessions. We do not consider one of the averaging methods to be superior to the 351

other; instead we provide the user with both options, allowing them to consider which 352

approach is particularly suitable to answer their questions. 353

We have exemplified the utility of the EZ-Root-VIS pipeline to represent the plastic 354

responses of various Arabidopsis accessions to environmental cues, with a particular focus on 355

LRS profiles. Indeed, this analysis helped us to identify extreme and interesting genotypes in 356

terms of their sensitivity to P or K limitation and combined deficiency. Under the low-P 357

conditions applied here none of the Arabidopsis accessions showed preferential growth 358

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 13: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

13

investment into upper (basal) lateral roots despite the widespread view that low-P adapted 359

RSA ideotypes preferentially explore residual P in the topsoil (Lynch and Brown, 2001). This 360

suggests that the accessions have not evolved in a P-limited environment, or that they only 361

extend laterals if they perceive an actual P gradient. Our pipeline also revealed that 362

interactive effect of K and P limitation modulate RSA in a genotype-specific manner that 363

could not have been predicted from measuring RSA under single deficiency or in one 364

accession only. 365

We have further validated the usefulness of the EZ-Root-VIS pipeline for facilitating GWAS 366

on RSA. A total of 56 loci controlling various root traits could be mapped at a cut-off 367

threshold of –log10(P) > 5.0. We adjusted the threshold to this level for two reasons: first, 368

SNPs in genes encoding known regulators affecting root traits such as IAA1/AXR5 and 369

ALF5 were associated with LRD-BZ and MRL with a –log10(P) > 5.0 and < 5% FDR 370

significance threshold, respectively. Second, some associations which are not significant at 5% 371

FDR, yet above –log10(P) > 5.0, have been shown to be false negatives, because multiple 372

testing correction methods are overly conservative (Kalladan et al., 2017; Meijón et al., 2013; 373

Müller et al., 2016). The vast majority of the loci identified here did not contain any 374

previously known RSA regulators. Indeed, the follow-up characterization of Col-0 knockout 375

mutants pointed to several genes with functions in RSA development, including AT4G09000 376

(GRF1), AT4G10270, AT4G10570 (UBP9), AT4G01550 (NTM2), AT3G29300, 377

AT5G51560 and AT3G04260 (PTAC3). We also found natural variation in genes that had 378

previously been shown to affect root traits such as AT4G14560 (IAA1), AT5G22300 (NIT4) 379

and AT3G23560 (ALF5) (Supplemental Datasets 5 and 6). These findings provide an 380

excellent starting point for understanding the genetics of previously unresolved traits such as 381

LRS (0.25) and MR angle, and the role of RSA in plant adaptation to their natural habitats. 382

Studying these traits can also provide insights into fundamental biological processes. For 383

example, MR angle studies are expected to advance our understanding of plagiogravitropism, 384

cell wall integrity (van der Does et al., 2017) and voltage-sensing (Kellermeier et al., 2014), 385

as Arabidopsis mutants impaired in cellulose biosynthesis or membrane depolarization show 386

altered MR angle. 387

Approaches such as GWAS become highly time and cost-effective if data for multiple traits 388

can be obtained from the same experiment. Using the EZ-Root-VIS pipeline, it is currently 389

possible to generate data for 20 root traits (more can be added) over a mapping population 390

comprising about 150 accessions in the course of a few days. While the throughput is lower 391

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 14: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

14

than for some other software packages (e.g. BRAT, Slovak et al., 2014) the RSAs quantified 392

by EZ-Root-VIS can be more complex and hence more traits can be extracted. Importantly, 393

the visual reconstructions of averaged root systems replace the need to rely on ‘representative’ 394

example pictures and enable fast integration of the measured individual RSA traits into 395

meaningful root system shapes, which can be considered a breakthrough in the field of plant 396

root biology. In publications, provision of averaged root system images rather than 397

representative images is critical for interpretation and follow-up studies and it may also 398

improve the reproducibility of results between various labs. Visual root shape reconstruction 399

can also aid breeding efforts aimed at improving plant resilience to soil-borne stresses, 400

facilitating the selection of desired root ideotypes from large phenotypic datasets. 401

EZ-Rhizo and Root-VIS have been developed over several years, and the versions released 402

with this paper have already been beta-tested by volunteer researchers. The software 403

therefore represents a community effort, and we will continue to make improvements in 404

response to suggestions and requests from the academic community. 405

406

MATERIAL AND METHODS 407

Software development 408

The EZ-Rhizo and Root-VIS applications, and their various plug-in modules (collectively 409

packaged as The Rhizo-II Root Biometrics Suite), were developed on, and for, the Microsoft®

410

Windows®

operating systems, in the C++ language, using Microsoft®

Visual Studio®

411

2010/2017. The graphical user interface (GUI) was implemented using objects derived from 412

the Microsoft Foundation Class (MFC) library and interaction with the XML database is built 413

on code from the CMarkup (V-11.5) C++ XML Parser (www.firstobject.com). The software 414

package can be downloaded from http://www.psrg.org.uk/download/Rhizo-64.msi (for 64-bit 415

platforms) or http://www.psrg.org.uk/download/Rhizo-32.msi (for 32-bit platforms); it is free 416

of charge but we ask users to register their installation. 417

The XL-Orate plug-in is an ‘application extension module’ (dynamic link library), which is 418

activated via the “Plug-Ins” command in the “File” menu. It was also written in C++ and 419

developed using the same tools and coding strategy as for the main programs. It requires 420

installation of the Microsoft Excel software on the user’s computer and interacts with Excel 421

directly (without user involvement) through programmed automation. 422

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 15: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

15

Root-VIS was developed to be used in conjunction with EZ-Rhizo. Nevertheless, in principle, 423

any dataset can be analysed with Root-VIS so long as it is presented in the correct format and 424

contains all the data required for the visual reconstructions. To facilitate data input from other 425

sources Root-VIS is already compatible with RSML (Lobet et al., 2015), and procedures for 426

enabling Root-VIS to read those data files are currently under development. 427

Visual reconstructions 428

The Root-VIS program uses a subtle, smart algorithm to reconstruct visually representative 429

forms, (optionally) adding ‘bends’ to roots based on the available information (the length to 430

vector ratio, and the number, position and orientation of lateral roots). We have implemented 431

five types of average visual reconstructions of root systems in Root-VIS, named Absolute 432

Averages, Binned Averages, Alpha Blends, Flag Plots, and LR Profiles. The information 433

available from the database, for a main root, comprises its path length (the total length of the 434

root, from base to apex), its vector length (the straight-line distance between base and apex), 435

the angle of its vector from vertical (positive angles being clockwise when looking at the root 436

from the back of the plate) and the number of lateral roots. Lengths are expressed in 437

centimeters and angles are in degrees. For a lateral root, the information also includes its 438

position (the distance along its parent root from its parent’s base). 439

Adding bending patterns 440

Roots are usually not straight and therefore any visualization has to accommodate the 441

difference between path length and vector length. However, the precise bending patterns are 442

currently not quantified by EZ-Rhizo. We have implemented different visualization options 443

in Root-VIS consisting of either straight lines representing path or vector length, or added 444

bends. For roots that have no sub-root, bends can be added in a pre-decided number, equally 445

spaced along the vector’s axis, with the displacement of each point from the axis being 446

calculated by the application of Pythagoras’ Theorem. However, for roots with one or more 447

sub-roots, a correlation has been demonstrated between the bending of a root and the 448

emergence of a lateral root and that lateral roots will preferentially form at bends and follow 449

an alternating directional pattern (Laskowski et al., 2008). We therefore decided to place 450

bends along the vector, not at equal intervals, but rather at points corresponding to the 451

position of each lateral root, with the direction of the off-axis displacement being determined 452

by the sign of the branch angle. If two consecutive lateral roots branch in the same direction, 453

Root-VIS adds an extra bend point between them, being displaced in the direction opposite to 454

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 16: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

16

that of the two real sub-roots. Finally, we need to allow for a degree of bending in the apical 455

part of the root: for this, we distribute the total amount of added ‘bend’ between the branched 456

and apical zones according to the relative lengths of these two root segments, and allow the 457

user to specify how many (equally-spaced) bends to add in the apical zone. Clearly, the 458

described procedure does not recreate the original bending pattern but applies existing 459

evidence and user’s choices to fill in missing information. While the displayed bending 460

pattern will not be faithful, the approach allowed us to correctly display both path and vector 461

length in one picture. 462

Averaged RSA; absolute and binned modes 463

The Root-VIS program provides two different methods for calculating the averaged RSA of a 464

given dataset, which we call “absolute averaging” and “binned averaging.” For absolute 465

averages, first, the mean parameters (length, vector and angle) for the main root are 466

determined by dividing the totals for all plants by the number of samples; for the angle 467

parameter, averages are formed using the absolute values (i.e. not including the sign) and the 468

modal sign is then given to the calculated mean. Next, the median number of lateral roots is 469

calculated. Then, for each lateral root, in order of appearance, their means are calculated (in 470

the same way as for the main root, with the addition of the position parameter). If a plant in 471

the dataset has less than the median number of lateral roots, zeros are given as the four 472

parameter values for any ‘missing’ roots, and the divisor for the parameter totals for those 473

lateral roots is reduced by one. Since LRs are numbered from base to apex in EZ-Rhizo any 474

‘missing’ lateral roots will always be at the tip of the parent root. 475

For the binned averaging algorithm, first, each main root within the dataset is split into three 476

sections: the basal zone, the branched zone and the apical zone as described (Armengaud et 477

al., 2009). The path and vector lengths are then established for each of these zones and 478

accumulated across all of the roots, and the means calculated. By adding each mean, the total 479

mean path length and mean vector length of the root are determined. Next, the mean angle 480

and median number of laterals are calculated as for absolute averages. However, to calculate 481

the mean parameters for each lateral root, we first split the branched zone into a number of 482

sections – or bins – equal to the mean number of lateral roots. The lateral roots for each 483

sample in the dataset are allocated to one of these bins according to their position. The mean 484

values for LR length, vector and angle are then calculated for each bin (as before) and for 485

visualization they are positioned at the midpoint of the bin section. This averaging algorithm 486

takes into account that the order of appearance does not necessarily reflect where a LR is 487

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 17: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

17

placed; for example, the 4th

lateral root in one plant could be located near the top of the main 488

root whereas in another it could be positioned in the middle. In the visual reconstruction the 489

representative average LR is placed at the halfway point of the respective parent root segment. 490

Alpha blends 491

The RSA reconstructions do not include an indication of the amount of variance between 492

samples in each dataset (although standard errors are included in the numerical output). The 493

alpha blend option allows the reconstructions of the individual roots to be overlaid in a semi-494

transparent fashion, thus indicating the degree of variance across the dataset. By default, 495

when creating alpha blends, the vector angles of the main roots are normalised to the average 496

vector angle for the samples included. Additional user-selectable options also allow for the 497

MR path lengths and/or vector lengths to be normalised. 498

Flag plots 499

The various components of a flag plot are indicated in Supplemental Figure 2; the flagpole is 500

divided into three sections, the lengths of which are proportional to the lengths of each of the 501

root zones (basal, branched and apical); the angles between the upper and lower edges of the 502

flag and the pole represent the mean insertion angles of the LRs (upper edge) and the slope of 503

the linear regression between the mean length of the LRs and their position on the main 504

root. Alternatively, the length of the upper edge can represent the average length of the LRs, 505

in which case the angle between the lower edge and the flagpole will not represent any 506

directly measured RSA data. The density of the flag’s fill color represents the average lateral 507

root density – the value of which is normalized (i.e. scaled to a value between 0 and 1) within 508

the given set of plots. 509

The software provides a number of options to control how to draw flag plots, including the 510

selections described above, selections for root path or vector data, and choice of fill color. 511

LR profiles 512

The fact that EZ-Rhizo determines the position of each LR allows simple visualization of 513

local differences in LR growth. To construct the LR profiles, the MR is divided into a user-514

defined number of sectors (2-10) and the LR data within each sector is represented as a 515

rectangle over the sector. The width of the rectangle can be chosen to represent either the 516

total LR size (added lengths of al LRs in the sector, LRS profile) or the mean length of the 517

LRs in the sector (LRL profile). 518

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 18: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

18

Plant material, growth conditions, and root image processing 519

Arabidopsis (Arabidopsis thaliana) accessions from the RegMap panel (Horton et al., 2012), 520

and homozygous T-DNA insertion mutant lines for candidate genes and their corresponding 521

wild types, Col-0 or Col-3, were obtained from the Nottingham Arabidopsis Stock Centre. 522

Seeds were surface sterilized in absolute ethanol for 1 min and then washed for 5 min with a 523

solution containing 2.8% (w/v) sodium hypochlorite and 0.1% (v/v) Tween®

-20 followed by 524

five washes with sterile distilled water. Seeds were incubated at 4°C for 5-7 days. The 525

sterilized and stratified seeds were sown on vertical plates with minimal media (Kellermeier 526

et al., 2014) containing 1% (w/v) agar (Formedium), 0.5% (w/v) sucrose and pH 5.6 (0.2 M 527

MES/Tris). For nutrient limitation experiments concentrations of K and P were lowered to 10 528

µM and 20 µM, respectively, and the osmotic potential of these media was adjusted as 529

described before (Kellermeier et al., 2014). Plants were a grown in a growth chamber at 60% 530

relative humidity and 20°C, with 9 h of light (120 µE m-2

s-1

). Images of each plate were 531

acquired using a flatbed scanner at 200 dpi as previously described (Kellermeier and 532

Amtmann, 2013). The RSA of each plant was quantified from the images using the EZ-Rhizo 533

as described before (Armengaud et al., 2009), facilitated by some new software functions 534

described in the Help files of the latest version of EZ-Rhizo package released with this 535

publication. 536

Statistical tests 537

Averaged root trait data obtained from Root-VIS using the XL-Orate plugin were used for 538

statistical analyses unless otherwise stated. Trait frequency distribution and Shapiro-Wilk test 539

of uniformity, correlation and agglomerative hierarchical clustering analyses were performed 540

using XLSTAT software. Genome-wide association mapping was conducted using GWAPP 541

web interface (https://gwas.gmi.oeaw.ac.at/) with 250K SNP data and the accelerated mixed-542

model (AMM) algorithm method (Seren et al., 2012). Statistically significant differences 543

between wild-type and mutant plants was assessed using a Student’s t test (*: p < 0.05) using 544

Microsoft®

Excel. 545

Accession numbers 546

Sequence data from this article can be found in the Arabidopsis Genome Initiative or 547

GenBank/EMBL databases under the following accession numbers: AT4G09000 (GRF1), 548

AT4G10270 (in locus LRS), AT4G10570 (UBP9), AT4G01550 (NTM2), AT3G29300 (in 549

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 19: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

19

locus LRDB), AT5G51560 (in locus LRK-LRN), AT3G04260 (PTAC3), AT4G14560 (IAA1), 550

AT5G22300 (NIT4), AT3G23560 (ALF5). See also Supplemental Data Sets 5 and 6. 551

Supplemental Data Files 552

The following materials are available in the online version of this article. 553

Supplemental Data Set 1: Numerical data for average RSA traits, number of replicate plants 554

and standard error underpinning the roots shown in Figure 1 E, F. 555

Supplemental Data Set 2: Numerical data for average RSA traits, number of replicate plants 556

and standard error underpinning the roots shown in Figure 2. 557

Supplemental Data Set 3: Means and SE of RSA traits of different accessions in four 558

nutrient conditions (data underpinning Figures 3, 4 and Supplemental Figure 3) 559

Supplemental Data Set 4: Means of RSA traits of 147 Arabidopsis accessions under control 560

conditions and hierarchical clustering of accessions based on root traits 561

Supplemental Data Set 5: Description of the GWAS data set. 562

Supplemental Data Set 6: Means and standard errors of root system architecture traits of 563

mutants of candidate genes identified through GWAS (data underpinning Figure 6 and 564

Supplemental Figure 6). 565

Supplemental Figures: Supplemental Figures 1-6 with legends, including: 566

Supplemental Figure 1. Screenshots of the Root-VIS software 567

Supplemental Figure 2. Visual explanation of the data incorporated into a Root-VIS flag 568

plot. 569

Supplemental Figure 3. Root-VIS representations of average RSAs of nine Arabidopsis 570

accessions in four different nutrient conditions. 571

Supplemental Figure 4. Frequency distribution of RS traits in Arabidopsis accessions. 572

Supplemental Figure 5. Genes and transcript profiles for two RSA associations. 573

Supplemental Figure 6. Candidate gene validation 574

Abbreviations 575

MRL Main root path length

MRV Main root vector length

MRA Main root angle

BsZL Basal zone length (from hypocotyl to the first lateral root)

BZL Branched zone length

AZL Apical zone length

TRS Total root system

LRS Total lateral root path length

LRS (0.25) Total lateral root path length in the top quartile of main root

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 20: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

20

LRL Average lateral root path length

LRL (0.25) Average lateral root path length in the upper quartile of main root

LRN Number of lateral roots

LRD-MR Lateral root density over the entire main root path (LRN/MRL)

LRD-BZ Lateral root density in the branched zone of the main root (LRN/BZL)

LRA Lateral root angle

OAD Overall depth

576

ACKNOWLEDGEMENTS 577

We are grateful to Geraldine Goldie who carried out preliminary consultation and 578

programming as part of a student project at the University of Glasgow. We are also grateful 579

to Mike Blatt for his support in the development of this software. The work was funded by 580

the BBSRC (BB/N018508/1) and by the Gatsby Charitable Trust (Sainsbury studentship to 581

FK). 582

583

584

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 21: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

21

FIGURE LEGENDS 585

Figure 1. Overview of EZ-Root-VIS pipeline 586

(A) EZ-Rhizo and Root-VIS software packages provide a convenient analysis pipeline 587

transforming root images into a numerical and statistical data output describing root system 588

architecture. 589

(B) A suitable image of Arabidopsis plants growing on a vertical agar plate can be acquired 590

with a flatbed scanner at 200 dpi. 591

(C) Skeletonized roots obtained after image processing with EZ-Rhizo provide the basis for 592

quantification of RSA features by EZ-Rhizo. The obtained data is saved in a searchable 593

database. 594

(D) Root-VIS re-constructs the individual roots using the data extracted by EZ-Rhizo. 595

(E-J) Root-VIS generates visual reconstructions of root system architecture from a user-596

defined set of individual roots (replicates), including absolute (E) and binned (F) average 597

RSA, alpha blends (G), flag plots (H) and LR profiles (I). The examples shown are based on 598

data from the five individual Arabidopsis plants shown in B. Roots images were taken at 12 599

DAG. 600

(J) For subsequent generation of graphs, statistical analyses and modelling the numerical data 601

obtained with Root-VIS is saved and can be displayed in Excel using the XL-Orate plug-in. 602

The screenshot shows an example Excel output from a large dataset. Data for each RSA 603

parameter is provided in a separate datasheet. MRL: Main root path length, LRN: lateral root 604

number, MRA: Main root angle, MRV: Main root vector length. 605

606

Figure 2. Visual representation of RSA development over time 607

(A) Change of selected RSA features over time displayed in a conventional bar graph. Plotted 608

are plant age in days after germination (x-axis), mean lateral root density over the branched 609

zone (LRD-BZ, y-axis), mean main root length (MRL, z-axis), and mean lateral root length 610

(LRL, color) of Arabidopsis Col-0 plants growing on control media. Numbers of roots 611

analyzed at each time point are given in (B). 612

(B-F) Root-VIS offers several options to visualize the RSA of many replicate plants; 613

including absolute (B) and binned (C) average RSA reconstructions, superimposition of 614

normalized RSAs in alpha blends (D) as well as shape reconstructions in the form of flag 615

plots (E) and LRS profiles (F). All Root-VIS reconstructions shown were based on EZ-Rhizo 616

data obtained from Arabidopsis Col-0 plants grown in control conditions. Plant age (in days, 617

d) and numbers of replicate roots (n) are given in (B). 618

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 22: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

22

Figure 3. Environment- and genotype-dependent growth investment into main root and 619

lateral roots 620

Lateral root size (LRS) profiles (A) and average RSA reconstruction (B) of Arabidopsis 621

accessions grown in control, low K, low P, and combined low P and low K (low PK) media. 622

Vertical lines represent the mean main root path length. The main root path was divided into 623

four equally sized sections and lengths of laterals were added within each section. The width 624

of each square represents the mean LRS of 3-6 replicate plants. 625

Figure 4. RSA traits of Arabidopsis accessions grown in different nutrient conditions 626

(A-E) Means and standard errors of selected RSA features of 12-day-old Arabidopsis 627

accessions grown in control (black bars), low K (blue bars), low P (red bars), or low PK 628

(green bars) media. The data was generated by EZ-Rhizo and means across replicates (n = 3-629

6 plants) were calculated with Root-VIS for (A) main root length (MRL), (B) total lateral root 630

size (LRS), (C) lateral root density over the branched zone (LRD-BZ), and (D) main root 631

angle (MRA). (E) Means and standard errors of lateral root length (LRL) within four sections 632

of the main root. Data were extracted from LRL profiles generated by Root-VIS and 633

transferred to Excel using the XL-Orate plug-in. 634

Figure 5. Use of the EZ-Root-VIS pipeline for large-scale natural variation studies 635

(A) Heatmap of pairwise correlations (Pearson correlation coefficient) of 16 RSA traits in 636

147 Arabidopsis accessions. Plants were grown in control conditions. The correlations 637

between different root features were calculated using means of 5 plants for each genotype. 638

Stars indicate significance at P < 0.05 (Student’s t test). 639

(B) Hierarchical clustering of Arabidopsis accessions by genotype. Calculation of similarity 640

was based on 15 mean RSA traits calculated by Root-VIS. See Supplemental Data Set 5 for 641

the class assignment of the individual accessions. 642

(C) Visual reconstructions of RSA and LRS profiles of the central accession of each cluster. 643

Accession names are colored according to (B). 644

Figure 6. Genome-wide association studies for root system architecture traits 645

(A) Manhattan plots for GWA mapping of three RSA traits; lateral root size over the basal 646

quartile of the main root (LRS (0.25)), total lateral root size (LRS), and total root size (TRS). 647

The horizontal dotted line corresponds to a 5% FDR threshold. Light blue ticks labeled 648

‘GRF1’ and ‘LRSL’ indicate the location of the most significant associations. 649

(B) LRS profiles of Arabidopsis Col-0 wild type and mutant lines. Plants were grown on 650

control media in three independent experiments. The total number of replicate roots 651

contributing to each LRS profile is given in brackets. 652

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 23: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

23

(C) Means and standard errors (n as shown in B) of some RSA traits in wild type Col-0 and 653

mutant lines. Significant differences to wild type are indicated by asterisks (P <0.05, 654

Student’s t test). 655

656

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 24: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

24

REFERENCES 657

Armengaud, P., Zambaux, K., Hills, A., Sulpice, R., Pattison, R.J., Blatt, M.R., and 658

Amtmann, A. (2009). EZ-Rhizo: Integrated software for the fast and accurate 659

measurement of root system architecture. Plant J 57: 945–956. 660

Arsenault, J., Pouleru, S., Messier, C., and Guay, R. (1995). WinRHlZOTM

, a Root-661

measuring system with a unique overlap correction method. HortScience 30: 906. 662

Bucksch, A., Burridge, J., York, L.M., Das, A., Nord, E., Weitz, J.S., and Lynch, J.P. 663

(2014). Image-based high-throughput field phenotyping of crop roots. Plant Physiol 166: 664

470–486. 665

Chevalier, F., Pata, M., Nacry, P., Doumas, P., and Rossignol, M. (2003). Effects of 666

phosphate availability on the root system architecture: large-scale analysis of the natural 667

variation between Arabidopsis accessions. Plant Cell Environ 26: 1839–1850. 668

Delory, B.M., Li, M., Topp, C.N., Lobet, G. (2018) archiDART v3.0: A new data analysis 669

pipeline allowing the topological analysis of plant root systems. F1000Res. 2018;7. 670

Delory, B.M., Baudson, C., Brostaux, Y., Lobet, G., du Jardin, P., Pagès, L., et al. (2016). 671

archiDART: an R package for the automated computation of plant root architectural 672

traits. Plant Soil 398: 351–365. 673

Gruber, B.D., Giehl, R.F.H., Friedel, S., and von Wirén, N. (2013). Plasticity of the 674

Arabidopsis root system under nutrient deficiencies. Plant Physiol 163: 161–79. 675

Horton, M.W. et al. (2012). Genome-wide patterns of genetic variation in worldwide 676

Arabidopsis thaliana accessions from the RegMap panel. Nat Genet 44: 212–216. 677

Julkowska, M.M. and Testerink, C.(2015). Tuning plant signaling and growth to survive 678

salt. Trends Plant Sci 20: 586–594. 679

Julkowska, M., Koevoets, I.T., Mol, S., Hoefsloot, H.C., Feron, R., Tester, M., 680

Keurentjes, J.J.B., Korte, A., Haring, M.A., de Boer, G.-J., and Testerink, C. (2017). 681

Genetic Components of Root Architecture Remodeling in Response to Salt Stress. Plant 682

Cell doi:10.1105/tpc.16.00680. 683

Kalladan, R., Lasky, J.R., Chang, T.Z., Sharma, S., Juenger, T.E., and Verslues, P.E. 684

(2017). Natural variation identifies genes affecting drought- induced abscisic acid 685

accumulation in Arabidopsis thaliana. PNAS 114: 11536-11541. 686

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 25: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

25

Kalogiros, D.I., Adu, M.O., White, P.J., Broadley, M.R., Draye, X., Ptashnyk, M., 687

Bengough, A.G., and Dupuy, L.X. (2016). Analysis of root growth from a phenotyping 688

data set using a density-based model. J Exp Bot 67: 1045–1058. 689

Kellermeier, F. and Amtmann, A. (2013). Phenotyping jasmonate regulation of root growth. 690

Methods Mol Biol 1011: 25–32. 691

Kellermeier, F., Armengaud, P., Seditas, T.J., Danku, J., Salt, D.E., and Amtmann, A. 692

(2014). Analysis of the root system architecture of Arabidopsis provides a quantitative 693

readout of crosstalk between nutritional signals. Plant Cell 26: 1480–1496. 694

Kellermeier, F., Chardon, F., and Amtmann, A. (2013). Natural variation of Arabidopsis 695

root architecture reveals complementing adaptive strategies to potassium starvation. 696

Plant Physiol 161: 1421–1432. 697

Laskowski, M., Grieneisen, V.A., Hofhuis, H., Ten Hove, C.A., Hogeweg, P., Marée, 698

A.F.M., and Scheres, B. (2008). Root system architecture from coupling cell shape to 699

auxin transport. PLoS Biol 6: 2721–2735. 700

Lobet, G., Pagès, L., and Draye, X. (2011). A Novel image-analysis toolbox enabling 701

quantitative analysis of root system architecture. Plant Physiol 157: 29–39. 702

Lobet G., Pound M.P., Diener J. et al. (2015) Root System Markup Language: toward an 703

unified root architecture description language. Plant Physiol 167:617–627. 704

Lynch, J.P. (2015) Root phenes that reduce the metabolic costs of soil exploration: 705

opportunities for 21st century agriculture. Plant Cell Environ 38:1775–1784. 706

Lynch, J.P. and Brown, K.M. (2001). Topsoil foraging - An architectural adaptation of 707

plants to low phosphorus availability. Plant Soil 237: 225–237. 708

Meijón, M., Satbhai, S.B., Tsuchimatsu, T., and Busch, W. (2013). Genome-wide 709

association study using cellular traits identifies a new regulator of root development in 710

Arabidopsis. Nat Genet 46: 77–81. 711

Morris, E.C., Griffiths, M., Golebiowska, A. , Mairhofer, S., Burr-Hersey, J. , Goh, T. , 712

von Wangenheim, D., Atkinson, B. , Sturrock, C. J. , Lynch, J.P. , Vissenberg, K., 713

Ritz, K. , Wells, D. M. , Mooney, S. J. , Bennett, M. J. (2017) Shaping 3D root system 714

architecture. Curr Biol 27: 919-930 715

Müller, L.M., Lindner, H., Pires, N.D., Gagliardini, V., and Grossniklaus, U. (2016). A 716

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 26: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

26

subunit of the oligosaccharyltransferase complex is required for interspecific 717

gametophyte recognition in Arabidopsis. Nat Commun 7: 10826 doi: 718

10.1038/ncomms10826. 719

Naeem, A., French, A.P., Wells, D.M., and Pridmore, T.P. (2011). High-throughput 720

feature counting and measurement of roots. Bioinformatics 27: 1337–1338. 721

Reymond, M., Svistoonoff, S., Loudet, O., Nussaume, L., and Desnos, T. (2006). 722

Identification of QTL controlling root growth response to phosphate starvation in 723

Arabidopsis thaliana. Plant Cell Environ 29: 115–125. 724

Ristova, D., Rosas, U., Krouk, G., Ruffel, S., Birnbaum, K.D., and Corruzi, G. (2013). 725

RootScape: landmark-based system for rapid screening of root architecture in 726

Arabidopsis. Plant Physiol 161: 1086–1096. 727

Rogers E.D., Benfey P.N. (2015) Regulation of plant root system architecture: implications 728

for crop advancement. Curr Opin Biotechnol 32: 93–98. 729

Satbhai, S.B., Setzer, C., Freynschlag, F., Slovak, R., Kerdaffrec, E., and Busch, W. 730

(2017). Natural allelic variation of FRO2 modulates Arabidopsis root growth under iron 731

deficiency. Nat Commun 8: 15603 doi: 10.1038/ncomms15603. 732

Seren, U., Vilhjalmsson, B.J., Horton, M.W., Meng, D., Forai, P., Huang, Y.S., Long, Q., 733

Segura, V., and Nordborg, M. (2012). GWAPP: a web application for genome-wide 734

association mapping in Arabidopsis. Plant Cell 24: 4793–4805. 735

Shahzad, Z. and Amtmann, A. (2017). Food for thought : how nutrients regulate root 736

system architecture. Curr Opin Plant Biol 39: 80–87. 737

Slovak, R., Su, X., Shimotani, K., Shiina, T., and Busch, W. (2014). A scalable open-738

source pipeline for large-scale root phenotyping of Arabidopsis. Plant Cell 26: 2390–739

2403. 740

Svistoonoff, S., Creff, A., Reymond, M., Sigoillot-Claude, C., Ricaud, L., Blanchet, A., 741

Nussaume, L., and Desnos, T. (2007). Root tip contact with low-phosphate media 742

reprograms plant root architecture. Nat Genet 39: 792–796. 743

Van der Does, D., Boutrot, F., Engelsdorf, T., Rhodes, J., Mckenna, F., Vernhettes, S., et 744

al. (2017). The Arabidopsis leucine-rich repeat receptor kinase MIK2 / LRR-KISS 745

connects cell wall integrity sensing, root growth and response to abiotic and biotic 746

stresses. PLoS Genet 13:e1006832. 747

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 27: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

27

Voß, U. et al. (2015). The circadian clock rephases during lateral root organ initiation in 748

Arabidopsis thaliana. Nat Commun 6: 7641 doi: 10.1038/ncomms8641. 749

Yu, P. , Gutjahr, C., Li, C.J. , Hochholdinger, F. (2016) Genetic control of lateral root 750

formation in cereals. Trends Plant Sci 21: 951-961 751

752

753

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 28: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 1. Overview of EZ-Root-VIS pipeline

(A) EZ-Rhizo and Root-VIS software packages provide a convenient analysis pipeline transforming root

images into a numerical and statistical data output describing root system architecture.

(B) A suitable image of Arabidopsis plants growing on a vertical agar plate can be acquired with a flatbed

scanner at 200 dpi.

(C) Skeletonized roots obtained after image processing with EZ-Rhizo provide the basis for quantification of

RSA features by EZ-Rhizo. The obtained data is saved in a searchable database.

(D) Root-VIS re-constructs the individual roots using the data extracted by EZ-Rhizo.

(E-J) Root-VIS generates visual reconstructions of root system architecture from a user-defined set of

individual roots (replicates), including absolute (E) and binned (F) average RSA, alpha blends (G), flag plots

(H) and LR profiles (I). The examples shown are based on data from the five individual Arabidopsis

plants shown in B. Roots images were taken at 12days after germination.. (J) For subsequent generation of graphs, statistical analyses and modelling the numerical data obtained with

Root-VIS is saved and can be displayed in Excel using the XL-Orate plug-in. Note that the screenshot shown

was extracted from a much larger dataset than the example shown in A-E. Data for each RSA parameter is

provided in a separate datasheet. MRL: Main root path length, LRN: lateral root number, MRA: Main root

angle, MRV: Main root vector length.

Image acquisition

Visual reconstruction

Create analysis

Export image/analysis

Root-VIS

Import image

Detect roots

Redefine main root

Save analysis

EZ-Rhizo

Image treatment

Downstream studies

(modelling, quantitative

genetics, physiology, breeding)

Image file .jpg, .bmp, …

Database XML

Data file .txt, .xlsx

A B

C

D

E F G H I

J

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 29: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 2. Visual representation of RSA development over time

(A) Change of selected RSA features over time displayed in a conventional bar graph. Plotted are plant age in days after

germination (x-axis), mean lateral root density over the branched zone (LRD-BZ, y-axis), mean main root length (MRL,

z-axis), and mean lateral root length (LRL, color) of A. thaliana Col-0 plants growing on control media. Numbers of

roots analyzed at each time point are given in (B).

(B-F) Root-VIS offers several options to visualize the RSA of many replicate plants; including absolute (B) and binned

(C) average RSA reconstructions, superimposition of normalized RSAs in alpha blends (D) as well as shape

reconstructions in the form of flag plots (E) and LRS profiles (F). All Root-VIS reconstructions shown were based on

EZ-Rhizo data obtained from A. thaliana Col-0 plants growing in control conditions. Plant age (in days, d) and numbers

of replicate roots (n) are given in (B).

4 d

(n=6)

Ab

s. A

vg.

B 6 d

(n=27)

8 d

(n=58)

10 d

(n=61)

12 d

(n=63)

14 d

(n=52)

Bin

. A

vg.

C

α-B

len

dF

lag P

lot

D

E

LR

S p

rofile

F

LRD-BZ

LRL (cm)

A

0.78

0.46

0.37

0.20

0.11

0.06

12

34

5

7

6

8

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 30: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 3. Environment- and genotype-dependent growth investment into main root and

lateral roots

Lateral root size (LRS) profiles (A) and average RSA reconstruction (B) of Arabidopsis

accessions grown in control, low K, low P, and combined low P and low K (low PK) media.

Vertical lines represent the mean main root path length. The main root path was divided into

four equally-sized sections and lengths of laterals were added within each section. The width

of each square represents the mean LRS of 3-6 replicate plants.

Control

Low K

Low P

Low PK

Shahdara T1080 Cerv-1 Dog-4 Wa-1 Gie-0 Ber N13 Aitba-2

Control

Low K

Low P

Low PK

B

A

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 31: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 4. RSA traits of Arabidopsis accessions grown in different nutrient conditions

(A-E) Means and standard errors of selected RSA features of 12-d old Arabidopsis accessions

grown in control (black bars), low K (blue bars), low P (red bars), or low PK (green bars)

media. The data was generated by EZ-Rhizo and means across replicates (n = 3-6 plants)

were calculated with Root-VIS for (A) main root length (MRL), (B) total lateral root size

(LRS), (C) lateral root density over the branched zone (LRD-BZ), (D) main root angle

(MRA). (E) Means and standard errors of lateral root length (LRL) within four sections of the

main root. Data were extracted from LRL profiles generated by Root-VIS and transferred to

Excel using the XL-Orate plug-in.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Contr

ol

Low

K

Low

P

Low

PK

Shahdara T1080 Cerv-1 Dog-4 Wa-1 Gie-0 Ber N13 Aitba-2

LR

L (

cm

)

E

0

2

4

6

8

10

02468

101214

LR

S (

cm

)

MR

L (

cm

)

0

5

10

15

20

LR

D-B

Z (

cm

-1)

A

C

B

D

-5

0

5

10

15

20

25

30

35

40

MR

A (

o)

Section 1Section 2Section 3

C K P PK

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 32: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 5. Use of the EZ-Root-VIS pipeline for large-scale natural variation studies

(A) Heatmap of pairwise correlations (Pearson correlation coefficient) of 16 RSA traits in

147 A. thaliana accessions. Plants were grown in control conditions. The correlations

between different root features were calculated using means of 5 plants for each genotype.

Stars indicate significance at P < 0.05 (Student’s t test).

(B) Hierarchical clustering of A. thaliana accessions by genotype. Calculation of similarity

was based on 15 mean RSA traits calculated by Root-VIS. See Supplemental Data Set 5 for

the class assignment of the individual accessions.

(C) Visual reconstructions of RSA and LRS profiles of the central accession of each cluster.

Accessions names are colored according to (B).

B

C

Da(

1)-

12

Lp2

-2K

ult

ure

n-1

Ct-

1Ta

-0V

an-0

WA

RH

od

Rsc

h-4

St-0

Ove

-0R

ak-2

Eden

-2W

l-0

Tom

egap

-2C

ol-

0Ei

-2D

o-0

Bay

-0Jl

-3N

13

HR

-5Se

i-0

Ty-0

Ste-

3U

ll2-5

Kn

-0Si

-0Lm

-2K

ro-0

Kel

ster

bac

h-4

Lillo

-1C

an-0

Ha-

0Sa

p-0

Li-7

Ag-

0Se

-0Li

aru

mH

s-0

Bo

r-1

Nz1

Sq-8

Mc-

0Lu

nd

Ws-

0U

trec

ht

Nw

-2G

el-1

Rev

-2B

g-2

Bsc

h-0

Bla

-1C

nt-

1P

la-0

Ro

u-0

Zu-1

Bo

ot-

1K

on

dar

aC

hat

-1Es

t-0

Mn

z-0

Ler-

1N

p-0

Ull2

-3Ts

u-0

Bu

r-0

Am

el-1

San

na-

2JE

AYo

-0A

a-0

Cvi

-0B

u-0

Ga-

0C

IBC

5Ed

i-0

An

-1W

a-1

Ts-1

Ste-

0Ta

mm

-2A

lc-0

Nc-

1T1

08

0R

mx-

A1

80

Hh

-0G

e-0

Ben

k-1

Ho

v4-1

In-0

Ba-

1G

ie-0

Je-0

Hey

-1P

og-

0G

ot-

7C

om

-1A

lst-

1G

r-1

Tin

g-1

Hn

-0A

ng-

0Jm

-1H

i-0

C2

4K

l-5

Ca-

0M

h-0

Ms-

0P

u2

-23

Or-

0R

a-0

NFA

-8R

ub

ezh

no

e-1

Pro

-0Lo

m1

-1Li

sse

Old

-1Ts

cha-

1R

en-1

Pn

a-1

7B

or-

4C

IBC

-17

Du

kG

y-0

Shah

dar

aFe

i-0

HSm

Kel

ster

bac

h -

2M

z-0

No

k-3

Hau

-0N

o-0

Lip

-0U

od

-7O

b-1

RR

S-7

Ho

vdal

a-2

Es-0

Mt-

0N

d-1

Dra

3-1

Ap

p1

-16

Oy-

0T1

11

0T1

13

0

0.68

0.73

0.78

0.83

0.88

0.93

0.98

Sim

ilarity

MRL MRV MRA BsZL BZL AZL TRS LRS LRS (0.25) LRL TQLRL LRA LRN LRD-MRLRD-BZ OAD

1 0.99* 0.20* 0.09 0.80* 0.83* 0.81* 0.56* 0.58* 0.31* 0.38* 0.11 0.62* -0.11 -0.53* 0.96* MRL

1 0.19* 0.10 0.78* 0.85* 0.80* 0.55* 0.57* 0.30* 0.38* 0.10 0.59* -0.14 -0.52* 0.97* MRV

1 0.19* 0.08 0.22* 0.02 -0.08 -0.09 -0.13 -0.08 0.09 0.00 -0.19* -0.12 -0.01 MRA

1 -0.08 0.05 -0.17* -0.31* -0.35* -0.20* -0.16 0.04 -0.34* -0.53* -0.25* 0.06 BsZL

1 0.37* 0.85* 0.73* 0.65* 0.38* 0.49* 0.10 0.81* 0.30* -0.54* 0.77* BZL

1 0.54* 0.27* 0.38* 0.17* 0.18* 0.07 0.29* -0.37* -0.30* 0.81* AZL

1 0.93* 0.89* 0.68* 0.70* 0.19* 0.84* 0.32* -0.28* 0.80* TRS

1 0.92* 0.79* 0.77* 0.21* 0.84* 0.53* -0.08 0.57* LRS

1 0.76* 0.78* 0.18* 0.75* 0.41* -0.07 0.59* LRS (0.25)

1 0.85* 0.14 0.38* 0.22* -0.12 0.32* LRL

1 0.13 0.48* 0.28* -0.16* 0.40* TQLRL

1 0.17* 0.10 0.09 0.08 LRA

1 0.69 -0.03 0.60* LRN

1 0.41* -0.10 LRD-MR

1

-

0.50* LRD-BZ

1 OAD

A

Col-0Lp2-2 Ste-3 Sanna-2 Mt-0Da(1)-12 N-13 Kn-0

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 33: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

1

Figure 6. Genome-wide association studies for root system architecture traits

(A) Manhattan plots for GWA mapping of three RSA traits; lateral root size over the basal

quartile of the main root (LRS (0.25)), total lateral root size (LRS), and total root size (TRS).

The horizontal dotted line corresponds to a 5% FDR threshold. Light blue ticks labelled

‘GRF1’ and ‘LRSL’ indicate the location of the most significant associations.

(B) LRS profiles of A. thaliana Col-0 wildtype and mutant lines. Plants were grown on

control media in three independent experiments. The total number of replicate roots

contributing to each LRS profile is given in brackets.

(C) Means and standard errors (n as shown in B) of some RSA traits in wildtype Col-0 and

mutant lines. Significant differences to wildtype are indicated by asterisks (P <0.05,

Student’s t test).

LRS (0.25)

LRS

TRS

GRF1LRSL

A

B CCol-0

(14)

at4g10270

(22)

grf1-1

(18)

Tra

it v

alu

e /cm

0

2

4

6

8

10

12

LRS (0.25) LRS TRS MRL

Col-0

grf1-1

****

**

*

at4g10270

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 34: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

Parsed CitationsArmengaud, P., Zambaux, K., Hills, A., Sulpice, R., Pattison, R.J., Blatt, M.R., and Amtmann, A. (2009). EZ-Rhizo: Integrated software forthe fast and accurate measurement of root system architecture. Plant J 57: 945–956.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Arsenault, J., Pouleru, S., Messier, C., and Guay, R. (1995). WinRHlZOTM, a Root-measuring system with a unique overlap correctionmethod. HortScience 30: 906.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Bucksch, A., Burridge, J., York, L.M., Das, A., Nord, E., Weitz, J.S., and Lynch, J.P. (2014). Image-based high-throughput fieldphenotyping of crop roots. Plant Physiol 166: 470–486.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Chevalier, F., Pata, M., Nacry, P., Doumas, P., and Rossignol, M. (2003). Effects of phosphate availability on the root systemarchitecture: large-scale analysis of the natural variation between Arabidopsis accessions. Plant Cell Environ 26: 1839–1850.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Delory, B.M., Li, M., Topp, C.N., Lobet, G. (2018) archiDART v3.0: A new data analysis pipeline allowing the topological analysis of plantroot systems. F1000Res. 2018;7.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Delory, B.M., Baudson, C., Brostaux, Y., Lobet, G., du Jardin, P., Pagès, L., et al. (2016). archiDART: an R package for the automatedcomputation of plant root architectural traits. Plant Soil 398: 351–365.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Gruber, B.D., Giehl, R.F.H., Friedel, S., and von Wirén, N. (2013). Plasticity of the Arabidopsis root system under nutrient deficiencies.Plant Physiol 163: 161–79.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Horton, M.W. et al. (2012). Genome-wide patterns of genetic variation in worldwide Arabidopsis thaliana accessions from the RegMappanel. Nat Genet 44: 212–216.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Julkowska, M.M. and Testerink, C.(2015). Tuning plant signaling and growth to survive salt. Trends Plant Sci 20: 586–594.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Julkowska, M., Koevoets, I.T., Mol, S., Hoefsloot, H.C., Feron, R., Tester, M., Keurentjes, J.J.B., Korte, A., Haring, M.A., de Boer, G.-J.,and Testerink, C. (2017). Genetic Components of Root Architecture Remodeling in Response to Salt Stress. Plant Celldoi:10.1105/tpc.16.00680.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Kalladan, R., Lasky, J.R., Chang, T.Z., Sharma, S., Juenger, T.E., and Verslues, P.E. (2017). Natural variation identifies genes affectingdrought- induced abscisic acid accumulation in Arabidopsis thaliana. PNAS 114: 11536-11541.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Kalogiros, D.I., Adu, M.O., White, P.J., Broadley, M.R., Draye, X., Ptashnyk, M., Bengough, A.G., and Dupuy, L.X. (2016). Analysis of rootgrowth from a phenotyping data set using a density-based model. J Exp Bot 67: 1045–1058.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Kellermeier, F. and Amtmann, A. (2013). Phenotyping jasmonate regulation of root growth. Methods Mol Biol 1011: 25–32.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Kellermeier, F., Armengaud, P., Seditas, T.J., Danku, J., Salt, D.E., and Amtmann, A. (2014). Analysis of the root system architecture ofArabidopsis provides a quantitative readout of crosstalk between nutritional signals. Plant Cell 26: 1480–1496.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Kellermeier, F., Chardon, F., and Amtmann, A. (2013). Natural variation of Arabidopsis root architecture reveals complementingadaptive strategies to potassium starvation. Plant Physiol 161: 1421–1432.

Pubmed: Author and Title www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 35: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

Google Scholar: Author Only Title Only Author and Title

Laskowski, M., Grieneisen, V.A., Hofhuis, H., Ten Hove, C.A., Hogeweg, P., Marée, A.F.M., and Scheres, B. (2008). Root systemarchitecture from coupling cell shape to auxin transport. PLoS Biol 6: 2721–2735.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Lobet, G., Pagès, L., and Draye, X. (2011). A Novel image-analysis toolbox enabling quantitative analysis of root system architecture.Plant Physiol 157: 29–39.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Lobet G., Pound M.P., Diener J. et al. (2015) Root System Markup Language: toward an unified root architecture description language.Plant Physiol 167:617–627.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Lynch, J.P. (2015) Root phenes that reduce the metabolic costs of soil exploration: opportunities for 21st century agriculture. Plant CellEnviron 38:1775–1784.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Lynch, J.P. and Brown, K.M. (2001). Topsoil foraging - An architectural adaptation of plants to low phosphorus availability. Plant Soil237: 225–237.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Meijón, M., Satbhai, S.B., Tsuchimatsu, T., and Busch, W. (2013). Genome-wide association study using cellular traits identifies a newregulator of root development in Arabidopsis. Nat Genet 46: 77–81.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Morris, E.C., Griffiths, M., Golebiowska, A. , Mairhofer, S., Burr-Hersey, J. , Goh, T. , von Wangenheim, D., Atkinson, B. , Sturrock, C. J. ,Lynch, J.P. , Vissenberg, K., Ritz, K. , Wells, D. M. , Mooney, S. J. , Bennett, M. J. (2017) Shaping 3D root system architecture. Curr Biol27: 919-930

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Müller, L.M., Lindner, H., Pires, N.D., Gagliardini, V., and Grossniklaus, U. (2016). A subunit of the oligosaccharyltransferase complex isrequired for interspecific gametophyte recognition in Arabidopsis. Nat Commun 7: 10826 doi: 10.1038/ncomms10826.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Naeem, A., French, A.P., Wells, D.M., and Pridmore, T.P. (2011). High-throughput feature counting and measurement of roots.Bioinformatics 27: 1337–1338.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Reymond, M., Svistoonoff, S., Loudet, O., Nussaume, L., and Desnos, T. (2006). Identification of QTL controlling root growth responseto phosphate starvation in Arabidopsis thaliana. Plant Cell Environ 29: 115–125.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Ristova, D., Rosas, U., Krouk, G., Ruffel, S., Birnbaum, K.D., and Corruzi, G. (2013). RootScape: landmark-based system for rapidscreening of root architecture in Arabidopsis. Plant Physiol 161: 1086–1096.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Rogers E.D., Benfey P.N. (2015) Regulation of plant root system architecture: implications for crop advancement. Curr Opin Biotechnol32: 93–98.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Satbhai, S.B., Setzer, C., Freynschlag, F., Slovak, R., Kerdaffrec, E., and Busch, W. (2017). Natural allelic variation of FRO2 modulatesArabidopsis root growth under iron deficiency. Nat Commun 8: 15603 doi: 10.1038/ncomms15603.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Seren, U., Vilhjalmsson, B.J., Horton, M.W., Meng, D., Forai, P., Huang, Y.S., Long, Q., Segura, V., and Nordborg, M. (2012). GWAPP: aweb application for genome-wide association mapping in Arabidopsis. Plant Cell 24: 4793–4805.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Shahzad, Z. and Amtmann, A. (2017). Food for thought : how nutrients regulate root system architecture. Curr Opin Plant Biol 39: 80–87.Pubmed: Author and Title www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from

Copyright © 2018 American Society of Plant Biologists. All rights reserved.

Page 36: EZ-Root-VIS: A Software Pipeline for the Rapid Analysis ... · (Armengaud et al., 2009). For example, EZ-Rhizo now accepts input images in any of the . 133. standard formats: Windows

Google Scholar: Author Only Title Only Author and Title

Slovak, R., Su, X., Shimotani, K., Shiina, T., and Busch, W. (2014). A scalable open-source pipeline for large-scale root phenotyping ofArabidopsis. Plant Cell 26: 2390–2403.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Svistoonoff, S., Creff, A., Reymond, M., Sigoillot-Claude, C., Ricaud, L., Blanchet, A., Nussaume, L., and Desnos, T. (2007). Root tipcontact with low-phosphate media reprograms plant root architecture. Nat Genet 39: 792–796.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Van der Does, D., Boutrot, F., Engelsdorf, T., Rhodes, J., Mckenna, F., Vernhettes, S., et al. (2017). The Arabidopsis leucine-rich repeatreceptor kinase MIK2 / LRR-KISS connects cell wall integrity sensing, root growth and response to abiotic and biotic stresses. PLoSGenet 13:e1006832.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Voß, U. et al. (2015). The circadian clock rephases during lateral root organ initiation in Arabidopsis thaliana. Nat Commun 6: 7641 doi:10.1038/ncomms8641.

Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

Yu, P. , Gutjahr, C., Li, C.J. , Hochholdinger, F. (2016) Genetic control of lateral root formation in cereals. Trends Plant Sci 21: 951-961Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title

www.plantphysiol.orgon June 6, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.