Root phenotyping to increase the
water use efficiency of wheat
Michelle Watt1, Sarah Rich1, Anton Wasson1, Vincent Chochois1, David Deery1, Richard Richards1,
Greg Rebetzke1, John Kirkegaard1, Richard Stirzaker1, Satish Misra2, Sai Prasad3, Ravish Chatrath4
1CSIRO,
Australia; 2ARI, India; 3IARI, India; 4DWR, India
Farmer + Science + Policy
100
area (mha)
80
production
(mt)
70
80,6
69,7
36,3
Dwarf Wheat
30
1,3
Bengal Famine
1942
0
2,9
2,7
50
10
3,2
55,1
60
20
0,7
9,7
6,5
Norin
0,9 10
11
92,4
85,9
Veery Lines
40
National Food
Security
90
5,0
94,8
12,9
2,3
1,6
23,8
22,3
24,2
2,9
3,1
4,5
4,0
3,5
3,0
2,5
Conservation Agric 2,0
Irrigation,
Fertilizer,
Agronomy
29,9
29,2
27,8
29,6
25,7
18,2
1,5
1,0
0,5
Biotechnology
0,0
World yield increases too slow to meet population
demands: prices rise
1961 to 1970
Population
Growth rate (%)
2.15
1971 to 1980
2.38
1981 to 1990
2.23
1991 to 2000
1.87
2001 to 2010
1.49
Overall
2.11
Period
Food production
growth rate (%)
1.85
2.07
2.73
2.10
1.90
2.47
Maize 1.6% per year
Rice 0.9% per year
Wheat 0.9% per year
Source FAOSTAT; Fischer and Edmeades, 2010, Crop Science
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Yield increases achieved through traditional breeding
Trial Block, DWR, Karnal, India
Photo: Ratan Tiwari
Wheat breeding station, New Zealand
Photo: Richard Richards
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Breeding for above-ground traits will hit a ceiling
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Target trait: Deeper roots in wheat
1st Green Revolution
1960s Rht shoot height genes
2nd Green Revolution?
Root depth genes?
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Current Rht genes reduce shoot height but not significantly affect root depth
140
Tall + Rht 1b
Tall + Rht 12
Tall + Rht 13
120
Shoot final height (cm)
100
80
60
40
20
0
-20
Root final depth (cm)
-40
-60
-80
-100
-120
-140
-160
(Watt and Ellis, unpublished field data)
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Dry countries share wheats and phenotyping to develop new
wheats with deep roots
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Field sites and climatic and soil conditions
Karnal
New Delhi
Indore
Pune
CSIRO
Many below ground root traits to speed up yield
increases and resource efficiencies:
But phenotyping is challenging
Laboratory screens fast but often in soil-less media
Laboratory screens often on seedling roots but deep, mature
roots are important in the field
Root measurements can be tedious
Imaging methods (X ray or rhizobox) constrain root systems
and they do not spread as in the field crop
Field variability poorly understood
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Photo: John Kirkegaard
Did not use seedling lab screens
because these may not correlate with
field deep roots (Watt 2013)
Did not rely on shoot measures as
these correlate weakly depending on
environment and genotype (Wasson et
al., 2014, submitted)
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Trait value: Deeper roots increase water use efficiency
and protect against drought at grain development
Many farming systems have deep water that is not taken up
by roots
Deep water valuable because protected from evaporation
Deep water predictable compared to rainfall (stored by the
farmer and measured at the start of the season)
In wheat a small increase in rooting depth can return a large
yield gain (every 10 cm has up to 10 mm water = 0.5
tonnes/ha)
Deep water has a high water use efficiency because it is taken
up during flowering and grain development, and used directly
to increase harvest index
(reviewed in Wasson et al., 2012., J Ex Bot)
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Approach
1. Assemble wheat germplasm
2. Phenotype for deep roots directly in at Indian and
Australian field sites
3. Identify deep root sources for breeding and marker
development
4. Higher throughput phenotyping
5. Complement marker development with model
Brachypodium
6. Field proof of concept with water monitoring
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
1. Diverse germplasm to increase chances of
identifying deep roots
Indian cultivars for rainfed regions that rely on deep,
monsoonal water
CSIRO-developed breeding lines with shoot traits
expected to enhance root depth (low tillering, shoot
vigour, dwarfing genes)
CIMMYT wheats selected on retreating profiles
Current Australian cultivars
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
2. Direct root coring to phenotype deep roots
Manual root coring - Karnal
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Manual Coring - Pune
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Manual Coring - Indore
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Root penetration of wheat
gentoypes
High throughput soil coring for phenotyping roots
- Australia
A trained team of four can core and count
720 cores in 3.5 days (90 lines, 8 reps)
Tractor mounted hydraulic corer
with lateral movement (1.8-2 m
long cores, 4 cm in diameter, 60 cm
lateral movement)
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Core break counting
=
1. Cut core into 10 cm sections
2. Break sections in half
3. Count roots on the interfaces
4. Keep some cores to be
washed out in the lab
5. Wash root out of cores
6. Scan roots to measure root
length
7. Correlate root counts to
scanned length
12 8. Calculate root lengths for
unwashed cores
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Core break counting - correlations
Mechanically washing cores
Scanner for roots (WinRhizo)
Correlations of counts to root length density
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Root depth and density measured in India
and Australia on 100s wheats to identify
extremes
Large range of maximum depth and
distribution patterns
huge genetic diversity
in root distributions
with depth
Environment (site) will
give a significant variation
of max depth of the
genotypes
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
3. Identified deep root sources and these will be
used for crossing and marker development
~20 cm deeper
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
What now: Getting deep rooted varieties
to farmers
immediately
provide deep
wheats to
breeders
Breeders cross
to adapted
varieties and
select for yield
Develop faster
way to select
for deep roots
Enrich varieties
for deep roots
Identify a gene
marker to breed
for deep roots
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
• Farmers given
high yielding
varieties;
• Breeder
diversity
enhanced
• Breeders and
farmers given
deep rooted
varieties;
• Breeders
given
Selection
tools to
continue
selection
4. Faster phenotyping using controlled environment
screens
Trait dissection of root traits possibly contributing to deep roots at maturity
Tube screen for root development traits assessed
• Root type numbers
• Timing of nodal root initiation
• Root branching
• Root depth
Plants are harvested at
staggered times up to the
5-6 leaf stage and traits
are assessed
Root emergence angle
• 2D seminal root angle screening
• 3D seminal & nodal root angle
screening
The root angle at which primary roots emerge
has been linked to the depth of the mature roots
in the field for several cereal species (e.g. rice,
Kato et al., 2006; sorghum, Mace et al., 2012;
wheat, Oyanagi et al., 1993b; Manschadi et al.,
2008).
5. Fast-tracking gene markers for deep roots using
mini-wheat: Brachypodium
Wheat Genome
16, 000 Mb (partially
sequenced)
32-39
40-54
45-60
Brachypodium
Genome
272 Mb
(sequenced)
Divergence times
Million years ago
(Vogel et al., 2010, Nature
Chochois et al., 2012, J Ex Bot)
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Gene marker to
select for fast
root growth
Root tip velocity
Bd
3…
0,7
mm/hour
0,6
0,5
0,4
0,3
Fast
Bd3-1
line
Root phenotyping to increase the water use efficiency of wheat | Ravish Chatrath
Slow
Bd21 line
Hall
(Vincent Chochois)
http://en.wikipedia.org/wiki/File:Dna-SNP.svg
6. Field proof of concept with water monitoring
mperature
Monitor soil and
canopy water use
with sensors linked
to the web for
breeders and
researchers to share
knowledge of gains
in water use
efficiency with new
deep rooted wheats
Data captured by smart phone
inexpensive sensor reader
$21 m
25
45
Depth
(cm) 65
85
115
Richard Stirzaker, CSIRO Land and Water
David
Deery,to HRPPC,
CSIRO
Plant
Industry
Root phenotyping
increase the water
use efficiency
of wheat
| Ravish Chatrath
145
Water sensors in the soil to depth
Thank you
Project Leaders:
Project Scientists:
[email protected]
Ravish Chatrath (India) and Michelle Watt (Australia)
Sai Prasad (Indore)
Satish Misra (Pune)
Mamrutha HM (Karnal)