Lyons agronomics

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Lyons agronomics

  1. 1. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 0 Graham Lyons B Agric Sci, MPH, PhD University of Adelaide, South Australia Agronomic biofortification to reduce Se deficiency in human populations: achievements and challenges
  2. 2. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 1 • Background: importance for health; variability in food systems • Genetic biofortification of Se in staple food crops: is it feasible? • Agronomic biofortification: summary of findings • Finland: national Se biofortification • Se-biofortified food products • Challenges: – Can large-scale Se agronomic biofortification reduce the incidence of a major human disease? – Low conversion efficiency in the field – The need to conserve a valuable micronutrient – Most efficient large-scale application method? • Proposed African program • Summary Contents
  3. 3. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 2 • Diverse selenoenzymes • Profound deficiency: Keshan disease and predisposal to Kashin-Beck disease • Immune function • Anti-ageing • Reduces heavy metal toxicity • Anti-viral, anti-cancer, anti-heart disease effects • Brain function • Fertility Why is Se important for humans?
  4. 4. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 3 • RDIs in the 55-85 µg/day range <40 too low and >200 may be too high • Some researchers suggest that a Se status of 120 µg/l in plasma is optimal in protecting against cancer • This should generally be achievable with an intake of around 90-110 µg Se/day How much Se do we need?
  5. 5. School of Agriculture, Food and Wine Life Impact | The University of Adelaide
  6. 6. Distribution of Se deficient soils and two diseases in China (adapted from Tan 2004) Selenium deficiency/KBD/KD
  7. 7. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Total soil Se is often unrelated to plant-available Se Location Total soil Se Se in wheat grain µg/kg Yongshou, China 700 20 Minnipa, SA 80 720 Charlick, SA 85 70 Dedza, Zimbabwe 30000 7
  8. 8. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Environmental variability in wheat grain Se at one site (S Australia, 2000) Site Variety Rep Grain Se (µg/kg) Bordertown Excalibur 1 120 2 110 3 690 4 520 Mean (se) = 392 (117) Range = 110-690
  9. 9. Selenium in wheat: enough genotypic variation to use in breeding ? • Surveys & field trials of diverse germplasm in South Australia & Mexico (total of 11 data sets) • Se range 5 - 720 µg/kg, mostly 80 – 250 µg/kg • Available soil Se is highly variable • No genotypic variation in grain Se density detected among modern wheat cultivars Rye & Aegilops tauschii may be higher for Se accumulation in grain (Lyons et al, Plant Soil 2005; 269:369-380) • Rice more promising, but is 55 v 35 µg/kg significant? • GM for Se tolerance: selenocysteine methyltransferase from Astragalus bisulcatus (Ellis et al, BMC Plant Biol 2004 Jan 28; 4:1)
  10. 10. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Agronomic Se biofortification field trials in South Australia 0 2 4 6 8 10 12 14 0 10 30 100 300 Selenate g/ha GrainSemg/kg Minnipa soil Charlick soil Minnipa foliar Charlick foliar
  11. 11. Agronomic biofortification of cassava with Se, Zn, I at CIAT, Colombia, South America
  12. 12. Harvest of biofortified cassava, Colombia
  13. 13. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Potato Soybean
  14. 14. School of Agriculture, Food and Wine Life Impact | The University of Adelaide
  15. 15. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Biofortified maize on the Loess Plateau
  16. 16. Se biofortification field trials on the Loess Plateau • Spring: maize, soybean, potato, cabbage; winter: wheat, canola • Relatively high Se application of 200 g/ha as selenate • No effect on yield • Biofortification by applying selenate to soil at planting was highly effective in all crops studied (and in pot trials) • Estimate that a Se target level of 300 µg/kg in grain can be achieved by applying just 13 g Se/ha at planting • Zinc and iodine biofortification by soil application was not effective, except for cabbage
  17. 17. Field trial: Se concentrations in edible parts of crops fold 118 80 126 159 450 6 maize soybean potato cabbage wheat canola control 0.0106 0.022 0.012 0.082 0.01 0.011 Selenium plus 1.2561 1.751 1.511 13.029 4.5 0.07 0 2 4 6 8 10 12 14 Seconcentration(mgkg-1DW)
  18. 18. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 18
  19. 19. Slide 19 Malawi Se-maize biofortification trials 2008-2010 Makoka site Chilimba, Broadley et al, unpublished
  20. 20. Slide 20 1970: East Karelia had the highest CVD rates in the world Low available Se in soils Se supplementation of livestock feeds commenced CVD (especially in men) began declining 1984: National Se biofortification program commences 1987: Se in spring wheat grain increases from 10 (pre-1984) to 250 µg/kg Se intake in human diet trebles Se in human plasma doubles (55 to 107 µg/l) CVD continues to decline (but at same rate as before) 2010: CVD relatively low (due to less smoking, improved diet and exercise, and possibly higher Se status) No detrimental Se effects observed. Se still added at 10 mg/kg in NPK Finland: Se biofortification at a national level
  21. 21. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Selenium benefits for plants Se “not known to be essential”, but: •Increased growth & tillering in rice (Wu et al, 1998) •Increased tuber yield in potatoes (Turakainen et al, 2004) •May stimulate chloroplastic cysteine desulphurases (Pilon-Smits et al, 2002) •Se + UVB increased growth in ryegrass & lettuce (Xue & Hartikainen, 2000) •Delayed senescence & increased growth in soybeans (Djanaguiraman et al, 2005) •Increased seed production and respiration in Brassica (Lyons et al, 2009) •Increased growth in mungbean associated with upregulation of carbohydrate metabolism enzymes (Malik et al, 2010)
  22. 22. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Se-treated Brassica: 44% more seed
  23. 23. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Se-biofortified wheat products in Australia www.laucke.com.au
  24. 24. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Se-biofortified wheat biscuits
  25. 25. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Sprouting biofortification
  26. 26. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Sprouting biofortification • Rye germinated and grown for 5 days while exposed to selenite • Completely transformed into organic Se • Can be blended to required Se level in flour • 100% Se recovery • Selenite may be more efficient than selenate for this purpose Bryszewska et al 2005; Food Additives and Contaminants 22(2): 135-140 Lintschinger et al 2000; J Agric Food Chem 48: 5362-5368
  27. 27. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 27 • Can Se agronomic biofortification improve health of low-Se groups/populations? – In particular, can it reduce incidence/prevalence of any important diseases? • What is the most efficient large-scale application method? – addition of selenate to fertiliser as in Finland? – but only 12-18% Se recovery in grain, and we should not waste this valuable micronutrient – could fortify salt with selenite (along with iodine), as in China • Applied Se usually does not increase yield, so why would farmers use it? – The simple answer is they wouldn’t – But if trials demonstrate tangible benefits, there would be a compelling argument for mandated Se addition to (subsidised) NPK fertilisers in certain areas, e.g. in Sub Saharan Africa Se agronomic biofortification: challenges
  28. 28. Slide 28 “Ecosystem services to alleviate trace element malnutrition in Sub-Saharan Africa” • Malawi & Zambia • Includes soil mapping, dietary diversification, fertiliser/soil amendment/intercropping trials (Se, Zn, I biofortification), human feeding trials, economic analysis • Sustainable conservation agriculture context • At planning/application stage; alliances established; based on successful Se agronomic biofortification trials with maize (Chilimba et al) • Led by Assoc Prof Martin Broadley, University of Nottingham Proposed African study
  29. 29. Slide 29 • Se application (g Se ha-1)0246Grain Se (mg Se kg-1 DW)0.000.050.100.150.200.25MakokaChilimbaADC et al.unpublished • Malawi fertilisation experiments 2008-2010
  30. 30. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 30 • Se is very important for human and animal health • Uneven distribution in soils and sub-optimal Se status is common • Agronomic biofortification of cereals and pulses is quite easy and provides desirable, bioavailable Se forms • Application of selenate to soil at planting (e.g. in fertiliser granules) is usually effective • Challenges include finding if large-scale Se biofortification in a low-Se region can improve human population health, and finding ways to improve application efficiency to reduce wastage Summary
  31. 31. School of Agriculture, Food and Wine Life Impact | The University of Adelaide Slide 32 • Funders: HarvestPlus, International Fertilizer Industry Assoc (IFA) & Prof Ismail Cakmak, Grains Research & Development Corporation (Aust.), Laucke Flour • Collaborators at Adelaide University (Prof Robin Graham, James Stangoulis, Yusuf Genc), NWAFU, Yangling, China (Prof Zhaohui Wang, Hui Mao et al), CIAT, Cali, Colombia (Hernan Ceballos, Fernando Calle et al) • Encouragement from Jerry Combs, Howdy Bouis, Gary Banuelos, Ismail Cakmak, Robin Graham, Martin Broadley • Editorial assistance from Ehsan Tavakkoli, Adelaide University • Waite Analytical Services (Teresa Fowles, Lyndon Palmer et al), Adelaide University Acknowledgement

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