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Marron N., Monclus R., Bonhomme L., Fichot R., Chamaillard S., Rasheed F., Toillon J., Villar M., Bastien C., Ceulemans R., Dreyer E. & Brignolas F.
International Poplar Symposium VIJuly 22, 2014 – Vancouver, British Columbia, Canada
Poplars originally restricted to riparian areas
Common selection criteria:
Productivity, trunk straightness, resistance to pathogens
Climate change, sustainable management of water resources
Water‐Use Efficiency (WUE) Drought tolerance
Additional selection criteria:
Productivity tightly dependent on water availability
Biomass production maintenance
TE = Biomass produced / Water usedWUEi = Assimilation / Stomatal conductance
Indirectly, Δ13C
Water‐Use Efficiency (WUE)
Can we adjust genotypes to site pedoclimatic conditions?
Can we buffer the decreases in biomass production due to
fluctuating water availability?
Variation? (Tn) Plasticity? (Tn+1)
Is Δ13C a robust predictor of WUE?
To what extent does WUE vary among and within hybrids?
How do environmental conditions affect WUE?
Are WUE and biomass production related?Is the relationship modulated by environmental factors?
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
More specifically:
Is there a relationship between WUE and drought tolerance?
Populus deltoides × P. nigra Populus deltoides × P. trichocarpa
Hybrid crosses mainly used in Europe
Greenhouse
Marron – 2003
Nursery
Monclus – 2006
Fichot – 2010
Short‐rotation coppice
Toillon – 2013
Dillen – 2009
Broeckx – 2013
Mature plantation
Bonhomme – 2009
Rasheed – 2012
From greenhouses to mature plantations
From 2‐month‐old cuttings to 14‐year‐old trees
Euramerican hybrids Interamerican hybrids
Related (F1 families) or unrelated hybrids (commercial genotypes)
Variations in WUE efficiently predicted by Δ13C,even when measured at different scales
S3K3
O3
S1S2
K2G3
W1B3
G4
S5S4O4
K4B5B4W3
W4
K1
W2
O5O6
O7
G2
G5 G1G6
W7W6K7
W5K6 B6B7K5 S7
R² = 0.33P < 0.0001
P
FC
A
R
I45
R² = 0.84P < 0.001
Δ13 C (‰
)188
At whole‐plant level:
TE = biomass / water‐use
Rasheed et al. 2012Plant Cell Environ.
TE (g L‐1)
21.2
21.7
22.2
22.7
23.2
23.7
24.7
24.2
9 10 11 12 13 14 15 16 17
At leaf level:
WUEi = A/gs
Broeckx et al. 2014Tree Physiol.
Δ13 C (‰
)
WUEi (mmol mol‐1)0.04 0.06 0.08 0.10 0.12 0.14
17
18
19
20
21
22
24
23
6 commercial genotypesSRC plantation
Plant material and conditions:6 commercial genotypes
Greenhouse
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
24
23
22
21
20
19
29 P. deltoides × P. nigra
Field nursery
Monclus et al. 2006New Phytol.
×
2003 2004
Δ (‰)
27
26
25
8 P. deltoides × P. nigra4 P. trichocarpa × P. deltoides
Mature plantations
Bonhomme et al. 2008Ann. For. Sci.
2005 2006
D×N D×T D×N D×T
50 F1 P. deltoides × P. nigra50 F1 P. deltoides × P. trichocarpa
Field nursery
Dillen et al. 2008Ann. Bot.
D×N D×T
×
×
×
×
18
Marron et al. 2005Tree Physiol.
31 P. deltoides × P. nigra
Greenhouse
Significant variation irrespective of hybrid crosses,relatedness, site conditions, age, etc.
Plant material and conditions:
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
Monclus et al. 2012BMC Plant Biology
330 F1 P. deltoides × P. trichocarpa progenyNursery
Only four QTL with minor effects (variance explained < 7%)
Plant material and conditions:
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
Response genotype‐dependentSelection of genotypes specific to site conditions
56 P. deltoides × P. nigra – 2 sites (ECH vs. SCV) – 2 planting densities
Toillon et al. 2013For. Ecol. Manage.
Δ13
C (‰
)
G × S***Echigey St Cyr-en-Val
12
22
20
18
16
14
Δ13
C (‰
)
G × D***18
22
21
20
19
1400trees.ha‐1
7200trees.ha‐1
Plant material and conditions:
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
7200 trees.ha‐1
G × D***
Δ13
C (‰
)
12
22
20
18
16
14
1400trees.ha‐1
7200trees.ha‐1
No trade‐off between biomass production and WUE
denserdenser
Toillon et al. 2013For. Ecol. Manage.
Plant material and conditions:
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
56 P. deltoides × P. nigra – 2 sites (ECH vs. SCV) – 2 planting densities
harsherharsher
Site conditions:
Planting densities:
Biomass decrease in response to drought:
: < 25%: from 25 to 50%
: > 50%
21
29 unrelated P. deltoides × P. nigra Field nursery
Irrigated vs. not irrigated
No simple relationship WUE is not a direct component of drought tolerance
Monclus et al. 2006New Phytol.
24
23
22
20
‐1.5 ‐1 ‐0.5 0 0.5 1 1.5
Δww (‰)
Δww ‐ Δwd (‰)
Plant material and conditions:
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
Need for a better understanding of physiological and molecular bases underlying WUE and its phenotypic plasticity
Need for data integration at different study scales
Δas predictor
Phenotypic variation
Phenotypic plasticity
Relationshipwith production
Link to drought tolerance
Robust
Potential for improving WUE without decreasing overall productivity
Significant No trade‐offGenotype‐dependent
Not simple