1. Physiological determination of oats yield: thoughts on promissory traits for further genetic gains Daniel Calderini Universidad Austral de Chile International Oat Conference Minneapolis, 2008

2. This presentation has the objective of: 1.Review few aspects of the effect of plant breeding on oat grain yield and associated traits 2.Analyze major grain yield components (i.e., grain number and grain weight) 3. Propose traits that could be useful to continue increasing yield potential 4. Propose a model of GW determination for temperate cereals

3. Introduction Grain crops are facing important challenges: - Expected increase of food demand - Alternative uses (biofuels) - Little opportunities for expanding arable land and irrigated areas - High grain production with low environmental impact

4. 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 80902000 Grain yield (Mg ha) Grain yield (Mg ha -1 ) Oat 8595 YearsWheat Barley Rye Slafer and Peltonen-Sainio (2001) In addition, some evidences are showing that grain yield of temperate cereals are leveling off Introduction

5. Plant breeding is the most cost effective, and environmentally safe, way of increasing grain yield The knowledge of physiological bases of grain yield determination could provide useful tools to plant breeding programs aimed at increasing yield potential

6. 1 2 3 4 5 6 191019301950197019902010 191019301950197019902010 191019301950197019902010 MinnesotaFinlandItaly Grain yield (Mg ha -1 ) Year of release y = 0.036x – 67.4 (r = 0.71; p<0.01) y = 0.099x – 15.7 (r = 0.66; p<0.05) y = 0.018x – 31.9 (r = 0.96; p<0.001) Oat breeding effect on grain yield Breeding Adapted from Wych and Stuthman (1983); Peltonen-Sainio (1990); Redaelli et al. (2008)

7. 0 1 2 3 4 2025303540 0 1 2 3 4 5 45505560 Grain yield (Mg ha -1 ) Harvest index (%) MinnesotaFinland y = 0.099x – 0.36 (r = 0.90; p<0.001) Relationship between grain yield and harvest index y = 0.114x – 2.2 (r = 0.54; p<0.05) Breeding Adapted from Wych and Stuthman (1983); Peltonen-Sainio (1990)

8. 0 2 4 6 8 10 0 2030405060 Oat Wheat Harvest index (%) Grain yield (Mg ha -1 ) Theoretical maximum HI Relationship between grain yield and harvest index in wheat and oat Breeding

9. DDSD SH Plant height (cm) Grain yield 70 100 Plant height optimum Richards (1992) Miralles and Slafer (1995) Breeding

10. Grain yield Grains m -2 = Grain Weight x Grain yield will be increased by improving major yield components

11. Argentina Australia India Italy Mexico UK Relationship between grain yield and grain number Calderini et al. (1999)

12. Variability of grain number, grain weight and grain yield (comparison between years) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 Spring barley Spring oat Spring wheat Winter wheat Winter rye Grain Number Grain Weight Yield Standard deviation/mean Adapted from Peltonen-Sainio et al. (2007)

13. Grain yield Grain weight Grains m -2 Sowing Emergence Anthesis Physiological Maturity Booting Harvest Tillering Adapted from Slafer and Rawson (1994) Major yield components and crop cycle

14. Emergence Anthesis Physiological Maturity Booting Harvest Tillering Adapted from Slafer and Rawson (1994) Grain number under stress Grain number Growth of reproductive organs

15. How to improve the growth of reproductive organs aimed at increasing grain number? 1.Higher partitioning of crop biomass to reproductive organs at pre-heading 2. Higher biomass production 3. Longer duration of the period when reproductive organs are growing Grain number

16. 1.Higher partitioning of crop biomass to reproductive organs at pre-heading Gonzalez et al. (2005) Grain number

17. Year of release Grain yieldStem weight (g m -2 ) (g m -2 ) 1920 319.9 839.1 1990 649.1 496.4 Difference 329.3 -342.7 Calderini et al. (1995) 1. Higher partitioning of crop biomass Grain number

18. Muurinen & Peltonen-Sainio (2006) Radiation interception Radiation use efficiency RUE at pre-heading ab bc 0.0 0.5 1.0 1.5 2.0 2.5 3.0 JamaAslakSuomi Cultivar Radiation use efficiency (g MJ -1 m -2 ) 2. Higher biomass production Grain number

19. Wheat RUE at pre-anthesis Amador & Calderini (unpublished) Radiation use efficiency (g MJ -1 m -2 ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OttoQuijote b a Cultivar Grain number

20. 0 100 200 300 400 500 600 700 OttoQuijote a b 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 b a Wheat Cultivar RUE RI Amador & Calderini (unpublished) Grain number

21. (Slafer et al., 1996) Adapted from Slafer and Rawson (1994) Growth of reproductive organs 3. Longer duration of the period when reproductive organs are growing Grain number

22. Whitechurch et al., (2007) In wheat and barley, clear differences between duration of pheno-phases have been found Grain number

23. Relative duration of pheno-phases in oat (14 cultivars and 6 lines from Finland) Vegetative / whole crop cycle Generative / whole crop cycle Range of relative duration (%) 14.3 – 17.4 32.0 – 36.5 Phenological phases Peltonen-Sainio & Rajala (2007) Grain number

24. Major yield components: Grain Weight Although more conservative than GN, GW could be a useful trait for continuing increasing yield potential of temperate cereals, especially if future plant breeding programs set more grains with lower GW potential Due to higher stability of GW, the knowledge of physiological bases of GW determination can help breeding programs to increase grain yield by improving GW

25. Major yield components: Grain Weight In oat, there are clear evidences that this trait has been increased by plant breeding (e.g., Wych and Stuthmann, 1983; Peltonene-Sainio, 1994)

26. Grain yield Grain weight Grains m -2 Sowing Emergence Anthesis Physiological Maturity Booting Harvest Tillering Adapted from Slafer and Rawson (1994) Assumptions on GN and GW determination

27. Temperature was increased (5.5°C) at different developmental phases in wheat, barley and triticale S Em Anthesis PM Heading Harvest Time DR TS Booting B-A H-A SE-B Ugarte et al. (2007) Effect of temperature on major yield components Grain weight

28. Effect of increased temperature on GN and GW Averaged across crops and experiments (3 years) H-A -7% B-A -15% SE-B -7% GNGW GN GW -8% -42%

29. Grain yield S Em Anthesis PM Head Harvest Time DR FI TE Grain weight Grains m -2 Booting This has important consequences for the study of grain weight determination

30. All these evidences are showing that flowers, which grow at the pre-anthesis period, are involved in GW determination Grain weight

31. New evidences of the involvement of the pre- anthesis period in GW determination gives support to promising molecular traits for increasing GW in temperate cereals

32. spikelet Different traits associated with GW were measured at central spikelets of the wheat spike G1 G2 G3 G4 rachis Grain weight

33. 36.351.055.552.7 Huayun 45.357.557.956.3 Pandora2 41.751.658.455.9 Huanil 42.752.657.953.5 Pandora12 42.565.172.167.8 Kambara 35.350.356.952.5 Bacanora3 36.357.866.261.5 Kambara 37.451.656.351.6 Bacanora2 41.860.365.262.3 Kambara 31.643.949.844.9 Bacanora11 G4G3G2G1 Grain weight (mg)CultivarSeasonExperiment Grain weight in two experiments Grain weight

34. y = 86.18x + 3.97 R 2 = 0.79 0 10 20 30 40 50 60 70 80 0,00,20,40,60,81,0 y = 126.93x – 5.93 R 2 = 0.86 0 10 20 30 40 50 60 70 80 0,00,20,40,60,81,0 Carpel weight at pollination, W10 (mg) Grain weight (mg) year 2006 year 2007 Relationship between grain weight and carpel weight Grain weight

35. Dynamic of grain dimensions PM 0 2 4 6 8 10 0 20304050 days after anthesis Grain dimensions (mm) Length Width Height Grain weight

36. y = 1.12x + 4.06 R 2 = 0.87 0 20 40 60 80 100 020406080100 Grain volume (mm 3) 3)3) 3) Grain weight (mg) y = 17.89x - 81.53 R 2 = 0.86 0 20 40 60 80 5678910 Grain length (mm) Grain volume (mm 3 ) Relationship between grain weight, grain volume and grain length Grain weight

37. 0 10 20 30 40 50 60 70 01020304050 days after anthesis Grain dry matter and water content (mg) Dynamic of dry matter and water content of grains Dry matter Water Maximum water content Grain weight

38. Relationship between grain weight and maximum water content of grains Grain weight (mg) Maximum water content (mg) Experiment 1 Experiment 2 y = 1,39x - 2,45 R 2 = 0,95 0 20 40 60 80 2030405060 y = 0,93x + 15,89 R 2 = 0,92 0 20 40 60 80 2030405060 Grain weight

39. Dynamics of water content and enlargement of grains Grain weight

40. 0 20 40 60 80 5678910 Grain length (mm) Grain weight or Maximum Water Content (mg) Relationship between grain weight or maximum water content and grain length GW MWC (r= 0.91; p<0.001) (r= 0.95; p<0.001) Grain weight

41. Grain length is associated with carpel weight 4 5 6 7 8 9 10 0.200.300.400.500.600.70 r = 0.75; p<0.01 Carpel weight at pollination (mg) Grain length (mg) year 2007 year 2006 Grain weight

42. Recurrent selection for grain yield in oat increased GW, grain area, grain length and grain width (De Koeyer et al., 1993) In the poster session of this conference, Hu et al. (2008) show data of GW and grain dimensions Relationship between GW and grain length: r 2 = 0.74; p<0.05 Grain weight

43. As a consequence of the relationship between final grain weight and carpel weight at anthesis, is proposed that the pericarp of grains is involved in grain weight determination. In other words, the final size of the pericarp is setting the potential weight of grains Pericarp growth is the result of the number of pericarp cells and the enlargement of these cells. Plant cell enlargement is controlled by proteins called expansins, which are involved in cell wall loosening (McQueen-Mason et al., 1992) Recently, expansin expression has been found in growing grains of wheat (Calderini et al., 2006; Liu et al, 2007) Grain weight

44. Preliminarily, we found the expression of 6 expansins in pericarp of grains at 10 days after anthesis from the experiment 2 - ExpA 2 - ExpA 4 - ExpA 6 - ExpA 8 - Exp novel 1 (similar to Festuca pratensis) - Exp novel 2 (similar to Oriza sativa) After this first step, ExpA 6 has been separated in 3 different goups: ExpA 6 a, ExpA 6 b and ExpA 6 c Expansins Grain weight

45. 0 2 4 6 8 0510152025 Days after anthesis Grain lenght (mm) 1,0 1,2 1,4 1,6 1,8 2,0 Expression of EXPA 6c (ID) Lenght Expansin Dynamics of grain length and ExpA 6c expresion in cultivar Bacanora Grain weight

46. AntisenseSenseNegative control Hybridization of Expansin A 6c in grains at 5 days after anthesis Grain weight

47. AntisenseSenseNegative control Hybridization of Expansin A 6c in grains at 10 days after anthesis Grain weight

48. Proposed Model of Potential Grain Weight Determination Carpels growth Lag Phase Carpel weight at pollination Endosperm cell number Physiological Maturity PollinationBooting Pericarp cells Water in grain Maximum water content Pericarp elongation Expansin expression

49. Conclusions - The overlapping of both GN and GW determination in temperate cereals is determination in temperate cereals is longer than generally assumed longer than generally assumed - The sensitivity of major yield components to environmental constraints during this to environmental constraints during this overlapping has been similar overlapping has been similar - There is not evidences of trade-off between GN and GW as a consequence of the GN and GW as a consequence of the overlapping between booting and anthesis overlapping between booting and anthesis

50. Conclusions - There are opportunities for increasing GN of temperate cereals. Differences between of temperate cereals. Differences between pheno-phases found in oats is a starting point pheno-phases found in oats is a starting point for using this trait in plant breeding programs for using this trait in plant breeding programs - The involvement of expansins in grain enlargement could be used for increasing enlargement could be used for increasing GW in temperate cereals GW in temperate cereals

51. Mrs. Carolina LizanaPh.D. Student (U. Austral de Chile) Dr.Ricardo RiegelAdjunt Professor (U. Austral de Chile) Dr. Simon McQueen-Mason Professor (U. of York)

52. Thank you!

53. Time (days after anthesis) Grain weight (mg) 0 10 20 30 40 50 60 01020304050 Grain growth rate Grain filling duration Usual approach for studying GW Grain weight

54. Response of sunflower yield components to shading Cantagallo et al. (2004)

55. 0 20 40 60 80 15.5 24.5 Pre-anthesis temperature (°C) Kernel weight (mg) Wardlaw (1994) Wheat Other evidences of the involvement of the pre- anthesis period in grain weight determination Grain weight

56. Relationship between GW and carpel weight at anthesis in wheat (data from different experiments) Calderini & Reynolds (2000) Grain weight

57. Grain number reduction relative to the control H-A +1% B-A -13% Wheat SE-B -40% Exp. 1 Exp. 2 H-A +3% B-A +4% -18%Barley SE-B -36% H-A -2% B-A -15% -16%Triticale SE-B -48% Ugarte et al. (2007)

58. Grain weight reduction relative to the control H-A -9% B-A -14% -19%Wheat SE-B -7% Exp. 1 Exp. 2 H-A -8% B-A -13% -21%Barley SE-B -8% H-A -9% B-A -15% -23%Triticale SE-B -6% Ugarte et al. (2007) Grain weight

59. y = 1.12x + 4.06 R 2 = 0.87 0 20 40 60 80 100 020406080100 Grain volume (mm 3) 3)3) 3) Grain weight (mg) Relationship between grain weight and grain volume Grain weight