Global Vision on Zinc

Global Vision on Zinc Ismail Cakmak Sabanci University, Istanbul

Zn Deficiency: a global nutritional problem incultivated soils (30 % of soils affected) Australia : >10 mio ha Turkey : 14 mio ha Bangladesh : 2 mio ha China : 30 mio ha India : 90 mio ha White and Zasoski, 1999; Field Crops Res., 60:11-26

Zn Deficiency:Global Micronutrient Deficiency in Soils Widespread Medium Alloway, 2007. IZA Publications, Brussels

Nearly half of the cereal cultivated soils globally contain low amount of plant available Zn (Graham and Welch, 1996)

Soil factors affecting availability of Zn to roots  high CaCO3  high pH SOIL  clay soils  low organic matter Zn  low soil moisture  high Fe and Al oxides Zn Zn Enhanced Zn adsorption Zn Zn and precipitation Zn Limited ZnZn uptake Decreased Zn desorption Zn Zn

Additional Cause of Zn Deficiency: Intensification of FarmingZinc Depletion in Soil and Zinc Dilution in the Harvested Products Increasing grain yield potential of new varieties results in rapid depletion of soil-Zn and dilution of seed-Zn

Why Plants Need Zinc

Basic Roles of Zinc in Biological Systems nearly 10 % of proteins needs Zn for their function and structure• structural and functional integrity of biological membranes depends on adequate amount of Zn• Zinc is a major actor of cellular defense systems against highly toxic oxygen free radicals ( better tolerance to environmental stress factors, e.g., drought stress)• Zinc is required for protection of IAA from oxidation• Zinc is required for better pollination Marschner, 1995; Cakmak, 2000, New Phytol.

Basic Roles of Zinc in Biological Systems• nearly 10 % of proteins needs Zn for their function and structure• structural and functional integrity of biological membranes depends on adequate amount of Zn• Zinc is a major actor of cellular defense systems against highly toxic oxygen free radicals ( better tolerance to environmental stress factors, e.g., drought stress)• Zinc is required for protection of IAA from oxidation• Zinc is required for better pollination Marschner, 1995; Cakmak, 2000, New Phytol.

Zinc Deficiency-Induced Root ExudationPathogenic Pathogenic Attack Amino acids, Attack Sugars..

ZINC PROVIDES DEFENSE AGAINST FREE RADICAL DAMAGE IN CELLSZINC IS NEEDED FOR O2 ZINC IS NEEDED FOR DETOXIFICATION h.v. e - INHIBITION OF OF FREE RADICALS ._ RADICAL GENERATION O2 1 O2 . H2O2 OH MEMBRANE DNA CHLOROPHYLL PROTEIN S-H S -H S=S S=S LIPID MUTATION CHLOROSIS PROTEIN PEROXIDATION DAMAGE CELL DEATH

Zn Deficiency Makes Plants Highly Sensitive to High Light and Heat Cakmak, 2000; New Phytologist, 146: 185-205

Partial shading of primary leaves of Zn-deficient bean plants

Importance of Zinc for Auxin (IAA) HormoneEvidence is available showing that Zn is involved in both biosytnhesis of IAA and also protection of IAA fromoxidative attack by free radicals less IAA synthesis Zn deficiency higher oxidative IAA degradation

Unde Zn deficiency IAA is Reduced Effect of Zn supply on shoot dry weight and composition of young leaves and shoot tips of bean plants. Concentrations in young leaves and shoot tips Zn supply Shoot Zn Free amino acids IAA M dry wt. g/plant mg kg-1 µmol g-1 dry wt. µg kg-1 fresh wt.+Zn (10-6) 8.24 52 82 240- Zn 3.66 13 533 122Zn-Resupply 4.53 141 118 180 Cakmak et al., 1989, J. Experimental Botany, 40:405

Reduced ShootElongation and +ZnLittle LeafFormation are veryCharacteristic for -ZnZn deficiency ‘little leaf’ Apple, N-China

Specific high Zn demand for pollinationEffect of Zn supply on growth, grain yield, viability and Zn concentration of pollen in maize plants Zn supply Shoot Dry Grain yield Pollen Zn conc. in Weight (g/plant) viability pollen (mg/ (g/plant) (%) kg) Adequate 74 70 85 75 Zinc Zinc 67 18 20 27 DeficiencySharma et al., Plant Soil 124, 221-226; 1990

Zinc Deficiency Symptoms in Wheat

Zn-adequate wheat leaf

Development of Zndeficieny in wheat

Zn deficieny in wheat

Severe Zndeficieny in wheat

Video:Growth of Maize and WheatPlants on a Zn-Deficient Soil

Human Zinc Deficiency

Micronutrient Deficiencies: Global Malnutrition Problem Iron ZincEstimated 2 Estimated billion www.harvestplus.org 2 billion

Zinc affects arange offunctions:• Immunity• Growth• Brain development• Reproduction•…. www.harvestplus.org

Human Zinc Deficiency High Moderate Low Not sufficient data available http://www.izincg.org/Soil and Human Zn Deficiency: geographical overlap Soil Zinc Deficiency Widespread Zn Deficiency Medium Zn Deficiency Alloway, 2004. IZA Publications, Brussels

Children particularly sensitive to Zn deficiency >450,000 deaths/year children under 5 – 4.4% attributed to Zn deficiency Black et al. 2008 The Lancet Maternal and Child Undernutrition Series

ZINC SAVES KIDS Intl’ Zinc Assoc.IZA in partnership with UNICEF started a program called ‘Zinc Saves Kids’ www.ZincSavesKids.org

Major Reason: Low Dietary IntakeHigh Consumption Cereal Based Foodswith Low Micronutrient Concentrations In number of developing countries, cereals contributes nearly 75 % of the daily calorie intake.

Solutions to Micronutrient Deficiencies • Supplementation • Food Fortification (not affordable in rural regions) Golden Wheat Fortfied with Zn

Agricultural Solutions(Breeding and Fertilizer Approaches) •Breeding •Agronomy/Fertilizers

HarvestPlus- Biofortification Challenge Program www.harvestplus.orgBreeding new cereal cultivars withhigh micronutrient content in cereal grainsCoordinating Institutions:International Food Policy Research Institute (IFPRI)Washington DC and CIAT-ColombiaMain Sponsors: Gates Foundation andWorld Bank

Main Sponsor of HarvestPlus Program www.gatesfoundation.org“Two billion people in the developing world suffer from dietslacking essential vitamins and minerals.Foods rich in vitamins and minerals are essential for a healthy diet.When diets do not contain sufficient amounts of vitamin A, folic acid,iodine, iron, and zinc, the consequences include significantly lowerbirth weight, a decrease in cognitive development, and increasedsusceptibility to other diseases.”

Rapid and Sustainable Solution Application of Zinc Fertilizers: (Agronomic Biofortification)Application of Zn-containing fertilizersoffers a rapid solution to the problem

Global Zinc Fertilizer Project II. Phase 2011 June- 2014 May

Rice Trials in Thailand

Maize Trials in Zambia

Wheat Trials in India

Maize Trials in Zimbabwe

WheatTrials in Pakistan

Maize Trials in Mozambique

Wheat trials in China, Yanglin-Xian

Thank you...

Staining/Localization of Zinc in Wheat Grain (red color) EMBRYOALEURONE ENDOSPERM ALEURONE Cakmak et al., 2010 Cereal Chemistry, 77: 10-20

LA-ICP-MS Tests on SeedsWhite arrow: Zn in 1000 900 Zn concentration (mg/kg)entire cross section 800 700 entire cross sectionBlack arrow: Zn in 600 500endosperm section 400 300 200 100 0 0 500 1000 1500 2000 2500 3000 3500 4000 Distance (µm) 12.0 Zn concentration (mg/kg) 10.0 8.0 6.0 4.0 endosperm section 2.0 Cakmak et al., 2010, 0.0 0 500 1000 1500 2000 J. Agric. Food. Chem. Distance (µm)

B LA-ICP-MS Tests No Foliar Zn Application 25 2000 Zn concentration (mg/kg) 1800 Zn concentration (mg/kg) 20 Endosperm 1600 1400 15 1200 1000 cr 10 800 600 5 400 200 0 0 0 500 1000 1500 2000 0 500 1000 1500 2000 2500 3000 3500 4000 Distance (µm) Distance (µm) Foliar Zn Application at Stem Elongation and Booting Stages 2000 25 Zn concentration (mg/Kg) 1800 Endosperm Zn concentration (mg/Kg) 1600 20 1400 1200 15 1000 800 cr 10 600 400 5 200 0 0 0 500 1000 1500 2000 2500 3000 3500 0 200 400 600 800 1000 1200 1400 Distance (µm) Distance (µm) Foliar Zn Application at Milk and Dough Stages 2000 25 Endosperm Zn concentration (mg/kg) 1800 Zn concentration (mg/kg) 1600 20 1400 1200 15 1000 cr 800 10 600 400 5 200 0 0 0 500 1000 1500 2000 2500 3000 3500 0 200 400 600 800 1000 1200 1400 1600 Distance (µm) Distance (µm)Cakmak et al., 2010, J. Agric. Food. Chem. 58:9092-9102

Global Vision on Zinc

by CIMMYT, Int. on Jun 28, 2012

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