root phenotyping€¦ · static root traits – measured at single time point dynamic root traits...
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Root phenotyping at Jülich Plant Phenotyping Centre (JPPC)
new routes to explore non-invasively the hidden half of plants
Kerstin A. Nagel - 17/02/2014
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Phenotyping the hidden half of plants – Why?
• Root system architecture can strongly affect yield
• Sustainable plant production requires root systems
optimised for growing conditions in the field
• Many of the traits required in future crops are tightly
linked to root properties:
- abiotic/biotic stress tolerance
- water and nutrient use efficiency
- yield...
However, root phenotyping is a challenging task,
mainly because of the hidden nature of this plant organ
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Non-invasive phenotyping of roots
• Allows repetitive analysis of the same plant or plant organ
• This enables finding phenotypic differences that occur:
- transiently
- at certain developmental stages
- under certain environmental conditions
• Combined with robotic systems – enables high-throughput screening
of large numbers of genotypes
• Overcome the phenotyping bottleneck
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Fiorani et al. 2012, Current Opinion Biotechnology
Non-invasive technologies are key to quantify plant structure and function
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Imaging plant function and structure is more than ‘taken pictures‘
Aim: measuring
quantitatively traits
Interpretation of images requires knowledge of
• sensor physics • sensor calibration • image analysis • plant traits
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Requirements for high throughput phenotyping
Automation of:
• quantitative image analysis
• plant cultivation (sowing – harvest)
• environmental monitoring
• data storage
• quality monitoring
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Development of root phenotyping facilities at JPPC
• reproducibly quantification of growth and architecture of roots
• elucidating dynamic establishment of roots in space and time
• interaction of root responses with aboveground plant part
• from artificial growth media to soil
• from controlled conditions to field environment
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Throughput: 300 plants – 15 min
Concept: plant-to-sensor
Nagel et al. 2009, Functional Plant Biology
Root phenotyping in artificial growth media
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Image analysis - quantify root system architecture
A
D C
B
• Image preprocessing
• Identification of local root elements
• Concatenating local root elements by following roots
• Crossings and branching
Mühlich et al. 2008, LNCS Nagel et al. 2009, Functional Plant Biology
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Root traits Global root traits • total root length • spatial distribution of roots
- root length density - rooting depth - root system width - area covered by roots
Root traits derived from individual roots • root length • number of roots • root diameter • branching angle
Static root traits – measured at single time point Dynamic root traits – related to dynamic changes
Nagel et al. 2009, Functional Plant Biology Nagel et al. 2012, Functional Plant Biology
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Nagel et al. 2009, Functional Plant Biology Füllner et al. 2012, Plant, Cell and Environment
Vertical temperature gradients for more realistic representation of field heterogeneity
Biomass (g)
Root temperature treatment (°C) 10 15 20 20-10
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Nagel et al. 2009, Functional Plant Biology
Branching angle of laterals is temperature dependent
Time after sowing (d)4 6 8 10 12 14
Branching angle (°)
40
45
50
55
60
65
70
75
10°C 15°C 20°C 20-10°C
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Root phenotyping of soil grown plants
Throughput: 60-240 plants – 60 min Concept: sensor-to-plant / plant-to-sensor Nagel et al. 2012, Functional Plant Biology
GROWSCREEN-Rhizo
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Simultaneous phenotyping of root and shoot traits
Shoot traits
Root traits
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Projected shoot area - 2D images (cm²)
0 100 200 300 400 500 600
Shoot biomass (g)
0
5
10
15
20
R² = 0.9505
Projected shoot area correlates with shoot biomass
Nagel et al. 2012, Functional Plant Biology
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Some parts of the root system are hidden in the soil
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0° 25° 43°
Ratio
visibl
e vs.
total
root le
ngth
(%)
0
10
20
30
40
Visible portion of a root system depends on the inclination angle of rhizotrons
α β
Nagel et al. 2012, Functional Plant Biology
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Plant species Visible portion of root system
Arabidopsis 77%
Rapeseed 42%
Barley 33%
Wheat 33%
Rice 32%
Brachypodium 24%
Maize 17%
Nagel et al. 2012, Functional Plant Biology
Visible portion seems to depend on root diameter
Arabidopsis Maize
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Visible root length correlates with total root length
Total root length (cm)0 500 1000 1500 2000 2500 3000
Visible root length (cm)
0
100
200
300
400
500
600
700
800
900
BarleyR² = 0.91
Nagel et al. 2012, Functional Plant Biology
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Root biomass (mg)0 20 40 60 80 100 120
Visible root length (cm)
0
100
200
300
400
500
600
700
800
900
BarleyR² = 0.92
Nagel et al. 2012, Functional Plant Biology
Visible root length correlates with root biomass
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Mechanical impedance affects root system architecture
Nagel et al. 2012, Functional Plant Biology
Time after sowing (d)6 8 10 12 14 16 18 20
Root system length (cm)
0
100
200
300
400
500
Low compactionModerate compaction
Root length density (cm cm-2)0.0 0.1 0.2 0.3 0.4 0.5
Depth (cm)0
20
40
60
80
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Pfeifer et al. 2014, Functional Plant Biology
On ‘low compacted side‘ of split root system • roots grow deeper and • lateral roots emerged earlier
Time after transplanting (d)
Lateral root development
low high
Split-root
high/high
low/low
Barley roots respond to localized soil compaction
low/low high/high low/high Split-root
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Root phenotyping non-invasively
• Screening for phenotypic plasticity
• Selection of root system architecture ideotypes for improved resource
use efficiency
• Identification of candidate genotypes with improved plant productivity
• Development of new phenotyping concepts for crop breeding