High resolution mapping of traits related to whole-plant transpiration under increasing evaporative demand in wheat

Transcription

1 High resolution mapping of traits related to whole-plant transpiration under increasing evaporative demand in wheat Walid Sadok, Rémy Schoppach, Julian D Taylor, Elisabeth Majerus, Elodie Claverie, Beata Sznajder, Delphine Fleury Stress Agronomy Group, UC Louvain

2 Vapor pressure deficit: the invisible drought VPD: vapor pressure deficit atmospheric drought Drives canopy transpiration (water use and CO 2 fixation) VPD H 2 O CO 2 TR VPD

3 Vapor pressure deficit: the invisible drought VPD: vapor pressure deficit atmospheric drought Drives canopy transpiration (water use and CO 2 fixation) VPD H 2 O Limited TR under high VPD improves yield in drought-prone areas (Sinclair et al. 2005; Kholová et al. 2010; Vadez et al. 2013) CO 2 TR VPD

4 Vapor pressure deficit: the invisible drought VPD: vapor pressure deficit atmospheric drought Drives canopy transpiration (water use and CO 2 fixation) VPD H 2 O Limited TR under high VPD improves yield in drought-prone areas (Sinclair et al. 2005; Kholová et al. 2010; Vadez et al. 2013) CO 2 TR Genetic variability in whole plant TR response to VPD: soybean (Sadok and Sinclair 2009), maize & sorghum (Gholipoor et al. 2010, 2013), wheat (Schoppach and Sadok 2012) VPD

5 Conservative water use under high VPD associated with drought tolerance in wheat TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 ) Pearson r=-0.74, P=0.03, R 2 =0.54 Schoppach and Sadok 2012 EEB TR sensitivity to soil water deficit

6 Conservative water use under high VPD associated with drought tolerance in wheat TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 ) Pearson r=-0.74, P=0.03, R 2 =0.54 Schoppach and Sadok 2012 EEB TR sensitivity to soil water deficit SAFE! RISKY!

7 Conservative water use under high VPD associated with drought tolerance in wheat TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 ) Pearson r=-0.74, P=0.03, R 2 =0.54 Drought tolerant line RAC875 Schoppach and Sadok 2012 EEB TR sensitivity to soil water deficit SAFE! RISKY!

8 Nocturnal TR seems to be involved in conservative behavior TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 ) Pearson r=0.96, P=0.007, R 2 =0.92 1:1 Schoppach et al 2014b FPB TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 )

9 Nocturnal TR seems to be involved in conservative behavior TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 ) Pearson r=0.96, P=0.007, R 2 =0.92 Drought tolerant line RAC875 1:1 Schoppach et al 2014b FPB TR sensitivity to VPD (mg H 2 O m -2 s -1 kpa -1 )

10 Using those strategies for breeding drought tolerant crops: 3 key challenges 1. What is the genetic basis for TR response to increasing VPD (SLP)? 2. Is there a genetic basis for nighttime TR (TRN)? 3. Can we identify candidate genes underlying those traits?

11 Whole plant TR response to increasing VPD Substantial genetic variability of TR response to VPD (143 DH lines) Linear responses confirmed for all lines, good quality of data 143 Regressions Schoppach et al Unpub.

12 Major QTL detected Total: 68 QTL; Broad-sense heritabilities between SLP: 6 QTL explaining 83.4% of %Var. TRN: 9 QTL explaining 71.1% of %Var. Trait QTL Name Position (cm) Size %Var LOD SLP QSLP.ucl-5A QSLP.ucl-2D QSLP.ucl-4A QSLP.ucl-3A TRN QTRN.ucl-5A QTRN.ucl-2D QTRN.ucl-5B QTRN.ucl-6A Schoppach et al Unpub.

13 Major QTL detected Total: 68 QTL; Broad-sense heritabilities between SLP: 6 QTL explaining 83.4% of %Var. TRN: 9 QTL explaining 71.1% of %Var. Only 1 common QTL for TRN & SLP Trait QTL Name Position (cm) Size %Var LOD SLP QSLP.ucl-5A QSLP.ucl-2D QSLP.ucl-4A QSLP.ucl-3A TRN QTRN.ucl-5A QTRN.ucl-2D QTRN.ucl-5B QTRN.ucl-6A Schoppach et al Unpub.

14 Major QTL detected Total: 68 QTL; Broad-sense heritabilities between SLP: 6 QTL explaining 83.4% of %Var. TRN: 9 QTL explaining 71.1% of %Var. Only 1 common QTL for TRN & SLP Trait QTL Name Position (cm) Size %Var LOD SLP QSLP.ucl-5A QSLP.ucl-2D QSLP.ucl-4A QSLP.ucl-3A TRN QTRN.ucl-5A QTRN.ucl-2D QTRN.ucl-5B QTRN.ucl-6A Schoppach et al Unpub.

15 Drought genes mapped in key SLP peak QTL region Schoppach et al Unpub.

16 Drought genes mapped in key SLP peak QTL region Schoppach et al Unpub.

17 Drought genes consistent with identified mechanism Findings highly consistent with a restricted K Root resulting from limited root metaxylem size and AQP-mediated water transport K Root_SA (m s -1 MPa -1 ) Whole root hydraulic conductivity Kurki Kukri p<0.005 (b) RAC875 Diameter (µm) Seminal root central Metaxylem diameter p<0.02 Kukri RAC875 Schoppach et al 2014a FPB 41

18 Conclusions 1. There is a robust genetic basis controlling TR response to increasing VPD in wheat 2. There is a clear & trait-specific genetic basis controlling nighttime TR 3. Genes specifically involved in root hydraulics likely involved in conservative behavior

19 Special thanks Elisabeth Majerus Rémy Schoppach Dr. Delphine Fleury, Pr. Peter Langridge, Dr. Julian Taylor Diego Wauthelet Elodie Claverie Dr. Boris Parent