A CONSORTIUM TO RAISE THE YIELD POTENTIAL OF WHEAT

1. A CONSORTIUM TO RAISE THE YIELD POTENTIAL OF WHEAT

2. Wheat and food security • Wheat Facts • Wheat grown on ~220 m ha worldwide • 600 m tons grain annually • 20% total calories of world population • Wide-scale adoption Green Revolution technologies (Evenson and Gollin, 2003). • But challenges to increase production are still considerable, especially in LDCs • Most are net importers of cereals (Dixon et al., 2009) • Lack urgently needed agricultural technologies (Kosina et al., 2007) • Majority located in climatically vulnerable regions (Lobell et al., 2008).

3. Bottleneck to yield: biomass • The international collaborative wheat improvement network -coordinated by CIMMYT- has focused on • Genetic disease resistance • Drought adaptation • End use quality • Raising genetic yield potential • Photosynthetic capacity has barely changed since wheat breeding began. • Basic research in photosynthesis suggests that substantial improvements in yield are theoretically possible (Long et al., 2006) • C4 crops (e.g. maize, sorghum, millet) show up to 50% greater radiation use efficiency (RUE) than C3 species (wheat, rice, beans, potatoes, most vegetables)

4. Comprehensive approach to increase yield potential Genetic modification of structural and reproductive aspects of growth will determine the net agronomic benefit of increased RUE: • Despite impact of Rht on improving HI, adaptation of reproductive processes to environment still a challenge to improving yield potential (Barnabas et al., 2008). • Wheat grown across widely divergent latitudes and temperatures • Poor adaptation may reduce yield independently of RUE (Miralles and Slafer, 2007) • Physiological and genetic basis of spike fertility needs to be better understood to ensure improved RUE is translated to agronomic yield

5. Structural failure (lodging) must be avoided in heavier yielding plants (Berry et al., 2007). • Lodging already a persistent phenomenon in wheat (Easson et al., 1993) • Reduces yield by as much as 80% and reduces grain quality • Heavier yielding crops will require stronger plants • Genetic improvement of stems and crown roots will be needed • Trade-offs between partitioning to spikes versus stems/roots must be optimized

6. Wheat Yield Consortium:Proposed research themes • 1) Increasing photosynthetic capacity and efficiency • Parry, Furbank et al • 2) Optimizing partitioning to grain yield while maintaining lodging resistance • Foulkes, Berry, Calderini, Davies, Griffiths, Marte, Miralles, Slafer, Sylvester-Bradley • 3) Breeding to accumulate yield potential traits • Bonnet, Manes, Mather, Angus, Reynolds

7. Drivers of yield potential Yield = Light interception (LI) X Radiation use efficiency (RUE) X Harvest Index (HI)

8. Light Interception (LI) • Relatively easy to select: • Early Ground Cover • Extended grain filling • Stay Green Phenotype miscanthus EMS TILLING line maize

9. Efficient use of light (RUE) • Leaf position • Leaf angle • N content • N use . Horton. 2000 JXB 51:475-485

10. Measuring photosynthesis IRGA Leaf porometry Canopy temperature Spectral reflectance

11. Selection for photosynthesis (source limited) Reynolds et al 2000 JXB 51: 459-473

12. Spike photosynthesis • Spikes may intercept 50% light during grainfill & contribute substantially to yield. • Measuring spike PS is challenging; and largely uninvestigated (Tambussi et al., 2007). • Recent field studies showed considerable genetic variation; may represent new focus to increase crop photosynthesis

13. RUE: CO2 fixation (transgenic approaches) Martin Parry John Andralojc Alfred Keys Josirley Carvahlo Huw Jones Mike Salvucci Christine Raines Jeroni GalmésGalmés Jaume Flexas Hipólito Medrano Inger Andersson

14. Rubisco initiates both photosynthesis & photorespiration glycerate glycerate-3P triose-P serine CO2 +NH3 CO2 hexose -P sucrose, RuBP starch O2 glycine H2O glycolate-2P ribulose-5P O2 Photorespiratory cycle Calvin cycle

15. Photorespiratory Losses Actual and potential rates of crop canopy photosynthesis v temperature Long et al 2006. Plant, Cell & Environment29, 315-330.

16. Increase Stomatal and Mesophyll conductance Crop improvement strategies Introduce CO2 pump +/- Kranz Anatomy C02 Calvin cycle Chloroplast Increase RuBP Regeneration Increase activity Increase kcat Increase Specificity

17. PG O2 Rubisco CO2. Mg2+ RuBP CO2 PGA Carboxylase & oxygenase occur at same active site; ratio of activity called Rubisco Specificity Factor (SF) SF = (RuBP carboxylated/RuBP oxygenated) x ([O2] / [CO2])

18. Specificity factor for Rubisco at 25oC

19. Parry’s Rubisco Forays

20. Specificity factor for Rubisco at 25oC 115 110 105 Specificity Factors 100 95 90 85 Crepis triasii Beta maritima Cistus albidus Mentha aquatica Limonium gibertii Pistacia lentiscus Lavatera maritima Kundmannia sicula Diplotaxis ibicensis Helleborus foetidus Rhamnus alaternus Digitalis minor minor Urtica membranacea Digitalis minor palauii Hypericum balearicum Paeonia cambessedesii Lysimachia minoricensis Limonium magallufianum Rhamnus ludovici-salvatoris Beta vulgaris subsp marcosii Urtica atrovirens subsp bianorii

21. Limonium gibertii (Sennen) Sennen

22. Relationship between Specificity factor & Kcat of Rubisco

23. C4 Photosynthesis mesophyll bundle sheath low CO2 high CO2 HCO3 RUBISCO OAA malate CO2 PEPC ME PEP PYR PPDK CHO chloroplast

24. C3 C4 ‘Furbank photosynthesis factory’

25. Hydrilla verticillata

26. Ways to increase net photosynthesis in current C3 crops Reynolds et al., 2009. JXB 60. 1899-1918

27. Theme 2: Optimising partitioning to grain yield while maintaining lodging resistance • SP2.1: Optimising harvest index through increasing partitioning to spike growth and maximizing grain number (Univ. Nottingham, CIMMYT) • SP 2.2: Optimizing developmental pattern to maximize spike fertility (Univ. Lleida, Univ Buenos Aires, INTA) • SP 2.3: Improving spike fertility through modifying its sensitivity to environmentalcues (Univ. Lancaster, Inst. Exp. Bot. AS CR, Prague, CzUfa Science Centre, Russia) • SP2.4 Improving grain filling and potential grain size (INRA, Univ. Austral Chile, Rothamsted Res) • SP 2.5: Identifying traits and developing genetic sources for lodging resistance (ADAS, CIMMYT, Limagrain) • SP 2.6 Modeling optimal combinations of, and tradeoffs between, traits (ADAS, DPI Victoria, Univ Birmingham)

28. Traits to optimize harvest index SP2.4 Increase pot. grain weight SP2.5 Improve lodging resistance +50%grain SP2.1 Optimize spike partitioning; alternative sinks SP2.3 Modify sensitivity to environmental cues for spike fertility flower -ing SP2.3 Enviornmental cues stem ext’n SP2.2 Optimize phenological partitioning for spike growth Theme 1: Increase Ps capacity & efficiency John Foulkes

29. Gustavo A. Slafer Centre UdL-IRTA Universitat de Lleida SP2.2 Studies manipulating photoperiod showed: (i) lengthof the stem elongation phase was clearly sensitive to photoperiod (ii) changes in in duration of stem elongation led to changes in spike fertility Slafer & Rawson, 1995, 1996, 1997. Whitechurch & Slafer, 2001; Slaferet al., 2001. Miralles, Ferro & Slafer, 2001.

30. 25 Gustavo A. Slafer Centre UdL-IRTA Universitat de Lleida 600 400 20 Stem elongation (ºCd) 200 15 0 Spikelet position within the spike +6 +0 Photoperiod extension (h) 10 5 0 0 2 4 6 Fertile florets González, Slafer & Miralles, 2003 , Field Crops Res. 81:29–38

31. Reduced floret abortion/(signalling?) More fertile florets & grains/m2 Improved yield and biomass Increasing partitioning to yield Greater RUE pre-anthesis Longer stem elongation phase Higher spike index and grain weight potential Adapted from Slafer et al 2005

33. Root and stem lodging

34. Anchorage strength Plant leverage ROOT lodging occurs if

35. Stem strength Shoot leverage STEM lodging occurs if

36. depth spread How to calculate anchorage strength Ground level

37. How to calculate stem strength

39. How to calculate shoot leverage Wind speed Ear area Shoots per plant Height at centre of gravity

41. Testing the model

42. Traits for lodging proof ideotype

43. Traits for lodging proof ideotype Stem & root biomass (t/ha) 8.8 7.7

44. Theme 3: Breeding to accumulate yield potential traits. • SP 3.1: Wide crossing to enhance photosynthetic capacity • SP 3.2: Genomic selection to increase breeding efficiency • SP 3.3: Trait and marker based breeding to combine traits

45. Wheat wild relatives in world collections The world collection was estimated by Konopka & Valkoun, ICARDA

46. Water Uptake • Access to water by roots • cool canopy (Reynolds & Tuberosa, 2008. COPB) Physiological breeding: strategic crossing for drought YLD = WU x WUE x HI (Passioura, 1979) • Photo-Protection • Leaf morphology • wax • Pigments • carotenoids • Transpiration Efficiency • WUE of leaf photosynthesis • low 12/13C discrimination Partitioning (HI) Remobilization stem carbohydrates

47. New generation of drought adapted wheat lines based on trait breeding

48. Conceptual models of yield potential traits: YIELD = LI x RUE x HI • SINKS (pre-grainfill): • Partitioning to developing spike (HI) • Reduce floret abortion (HI) • Optimize phenological pattern (HI) • Lodging resistance (HI) • SINK (grain-filling) • Partitioning to grain (HI) • Abort weak tillers (HI) • Adequate roots for resource capture (HI/RUE) • SOURCE (grain-filling): • Canopy photosynthesis (RUE/LI) • cellular (e.g. heat tolerance) • light distribution • N distribution/partitioning • spike photosynthesis • stay green • SOURCE (pre-grainfill): • Light interception (LI) • CO2 fixation (RUE) • Rubisco • C4 type traits

49. Phenotype SATs (leaf photosythesis) Biomass (RUE) Canopy architecture Pigment composition Chla:b carotenoids Harvest Index Phenological pattern Spike index Molecular marker Adaptation (GME) Ppd/Vrn Rht Lodging traits Stem wall composition Crown root spread Spike photosynthesis Signalling Selection trait or molecular marker?

50. TRAINING POPULATION SAWYT/WAMMI Development of genomic prediction models Choice of 20-25 crosses made between elites related to the training population Rapid Cycling: Two or three cycles of genotypic selection and intercrossing of selected plants C0(F2)  C1 C2  C3 Field Selection C3  C3S1  C3S2 ALs  YT1 YT2 Trait Improved Germplasm INTERNATIONAL YIELD TRIAL Genome-wide selection scheme