1
Low A High A Mean Reference Crown LR ms Passot S. 1 * , Meunier F. 2 , Couvreur V. 1 , Muller B. 3 , Javaux M. 2 , Draye X. 1 , Guédon Y. 4 , Laplaze L. 5,6 1 Earth and Life Institute - Agronomy, UCL, Louvain-la-Neuve, Belgium 2 Earth and Life Institute - Environment, UCL, Louvain-la-Neuve, Belgium 3 LEPSE, INRA, Montpellier, France 4 AGAP, Cirad, Montpellier, France 5 DIADE, IRD, Montpellier, France 6 LMI LAPSE, IRD, Dakar, Senegal * [email protected] Digitalization with SmartRoot Explicit cross section hydraulics Root anatomy Haagen-Poiseuille law Growth conditions: Sandy soil, initially wet, transpiration of 40cm 3 /day RootTyp Context Diversity has been observed in the anatomy and growth patterns of lateral roots in cereals. This may impact water uptake and could therefore increase cereal performances under drought. This study focuses on pearl millet, a key crop for food security especially tolerant to drought. Objectives The objective was to provide an integrated description of pearl millet lateral root development at early stages and to assess the impact of the existing diversity among lateral roots on water uptake using simulations. Material and methods Simulations were done with reference architecture, with extreme observed proportions of LRs and with a synthetic “mean + sd” homogeneous behavior for all LRs. Transpiration is fixed (40cm³/d) while Ψ (water potential) at the collar depends on the ability of the root system to take up water. Root development dynamics Phenotyping in rhizotron Digitalization Radial conductance Axial conductance Water uptake simulation with R-SWMS Simulation of root system architecture CellSet Low A High A Mean Ref. LR A 0.05 0.21 0 0.14 LR B 0.18 0.30 0 0.24 LR C 0.77 0.49 0 0.62 LR ms 0 0 1 0 Simulated root systems (RootTyp) Conclusion Three types of LRs identified in pearl millet based on growth profiles & anatomy Existence of three distinct types would delay drought sress Largest LRs contribute the most to water uptake and their contribution reaches a plateau around the usually observed proportions of LRs In the lab In silico Transversal sections Results Using a semi-Markov switching linear model lateral root (LR) growth profiles cluster into three groups. 0 0.05 0.1 0 10 20 30 0 0.02 0.04 0.06 0 10 20 30 40 0 0.1 0.2 0.3 0 10 end B C 0.14 0.52 0.24 0.10 A 14 . 0 ˆ , 17 . 0 ˆ , 6 . 0 ˆ C B A 0 10 20 30 1 3 5 7 9 A B C end Estimated growth rate (mm.day -1 ) Growth duration (days) Three distinct LR anatomies were found which correlate with groups based on growth profiles Plants with only one type of LRs would experience drought earlier than those with three types, regardless of proportions 1 2 3 Crown root Scale bar: 100μm Scale bar: 20μm Passot, S., Gnacko, F., Moukouanga, D., et al. (2016). Characterization of Pearl Millet Root Architecture and Anatomy Reveals Three Types of Lateral Roots. Front. Plant Sci. 7, 111. Pagès, L., Vercambre, G., Drouet, JL., et al. (2004) Root Typ: a generic model to depict and analyse the root system architecture. Plant and Soil 258: 103. Lobet, G., Pagès, L., and Draye, X. (2011). A novel image-analysis toolbox enabling quantitative analysis of root system architecture. Plant Physiol. 157, 2939. Javaux, M., Schroder, T., Vanderborght, J., and Vereecken, H. (2008) Use of a three-dimensional detailed modelling approach for predicting root water uptake, Vadose Zone J. 7, 10791088. Simulations indicate that LR A take up most of water. Further simulations show that this contribution to water uptake reaches a plateau around the observed proportion of LR A . Ø 100 μm, 2 periph XTE Ø 250 μm, 1 central + 3 periph XTE Ø 380 μm, 1 central + 7 periph XTE, aerenchyma 0 10 20 30 40 50 0 50 100 150 Central XTE Diameter (μm) Stele Diameter (μm) Type A Type B Type C Water uptake by A LR (cm 3 /d) Proportion of LR A Observed range mean with 0 < %A < 50%, %A < %B & 0 < B Low A High A Mean Reference [days] 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Low A High A Mean Reference Root system conductance (cm³/hPa/d)

Passot S. , Meunier F. , Couvreur V. , Muller B. , Javaux ... · A U B U C 0 10 20 30 1 3 5 7 9 A B C e .day end-1) Growth duration (days) Three distinct LR anatomies were found which

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Page 1: Passot S. , Meunier F. , Couvreur V. , Muller B. , Javaux ... · A U B U C 0 10 20 30 1 3 5 7 9 A B C e .day end-1) Growth duration (days) Three distinct LR anatomies were found which

Low A High A Mean Reference

Cro

wn

LR

ms

Passot S.1*, Meunier F.2, Couvreur V. 1, Muller B.3, Javaux M.2, Draye X.1, Guédon Y.4, Laplaze L.5,6

1Earth and Life Institute - Agronomy, UCL, Louvain-la-Neuve, Belgium 2Earth and Life Institute - Environment, UCL, Louvain-la-Neuve, Belgium 3LEPSE, INRA, Montpellier, France 4AGAP, Cirad, Montpellier, France 5DIADE, IRD, Montpellier, France 6LMI LAPSE, IRD, Dakar, Senegal * [email protected]

Digitalization with SmartRoot

Explicit cross section hydraulics

Root anatomy Haagen-Poiseuille law

Growth conditions: Sandy soil, initially wet,

transpiration of 40cm3/day

RootTyp

Context Diversity has been observed in the anatomy and growth patterns of lateral roots in cereals. This may impact water uptake and could therefore increase cereal performances under drought. This study focuses on pearl millet, a key crop for food security especially tolerant to drought. Objectives The objective was to provide an integrated description of pearl millet lateral root development at early stages and to assess the impact of the existing diversity among lateral roots on water uptake using simulations.

Material and methods

Simulations were done with reference architecture, with extreme observed proportions of LRs and with a synthetic “mean + sd” homogeneous behavior for all LRs. Transpiration is fixed (40cm³/d) while Ψ (water potential) at the collar depends on the ability of the root system to take up water.

Root development dynamics

Phenotyping in rhizotron

Digitalization Radial

conductance

Axial conductance

Water uptake simulation

with R-SWMS

Simulation of root system architecture

CellSet

Low A High A Mean Ref.

LRA 0.05 0.21 0 0.14

LRB 0.18 0.30 0 0.24

LRC 0.77 0.49 0 0.62

LRms 0 0 1 0

Simulated root

systems (RootTyp)

Conclusion Three types of LRs identified in pearl millet based on growth profiles & anatomy Existence of three distinct types would delay drought sress Largest LRs contribute the most to water uptake and their contribution reaches a plateau around the usually observed proportions of LRs

In the lab In silico

Transversal sections

Results Using a semi-Markov switching linear model lateral root (LR) growth profiles cluster into three groups.

0

0.05

0.1

0 10 20 30

0

0.02

0.04

0.06

0 10 20 30 40

0

0.1

0.2

0.3

0 10

end

B C 0.14 0.52 0.24

0.10

A

14.0ˆ,17.0ˆ,6.0ˆCBA

0

10

20

30

1 3 5 7 9

A

B

C

end

Est

imat

ed g

row

th r

ate

(mm

.day

-1)

Growth duration (days)

Three distinct LR anatomies were found which correlate with groups based on growth profiles

Plants with only one type of LRs would experience drought earlier than those with three types, regardless of proportions

1

2

3

Crown root Scale bar: 100μm

Scale bar: 20μm

Passot, S., Gnacko, F., Moukouanga, D., et al. (2016). Characterization of Pearl Millet Root Architecture and Anatomy Reveals Three Types of Lateral Roots. Front. Plant Sci. 7, 1–11.

Pagès, L., Vercambre, G., Drouet, JL., et al. (2004) Root Typ: a generic model to depict and analyse the root system architecture. Plant and Soil 258: 103. 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. Javaux, M., Schroder, T., Vanderborght, J., and Vereecken, H. (2008) Use of a three-dimensional detailed modelling approach for predicting root water uptake, Vadose Zone J. 7, 1079–1088.

Simulations indicate that LRA take up most of water. Further simulations show that this contribution to water uptake reaches a plateau around the observed proportion of LRA.

Ø 100 μm, 2 periph XTE Ø 250 μm, 1 central + 3 periph XTE

Ø 380 μm, 1 central + 7 periph XTE, aerenchyma

0

10

20

30

40

50

0 50 100 150

Cen

tral

XTE

Dia

met

er (

μm

)

Stele Diameter (μm)

Type A Type B Type C

Wat

er u

pta

ke b

y A

LR

(cm

3/d

)

Proportion of LRA

Observed range mean

with 0 < %A < 50%, %A < %B & 0 < B

Low A High A Mean Reference

[days]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Low A High A Mean Reference

Ro

ot

syst

em c

on

du

ctan

ce

(cm

³/h

Pa/d

)