Global Vision on ZincGlobal Vision on Zinc

Ismail Cakmak

Sabanci University, Istanbul

Zn Deficiency: Zn Deficiency: a global nutritional problem in a global nutritional problem in

cultivated soilscultivated soils ((30 % of soils affected)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

ZZnn Deficiency: Deficiency: Global Global Micronutrient Deficiency in SoilsMicronutrient Deficiency in Soils

Alloway, 2007. IZA Publications, Brussels

Widespread

Medium

Nearly half of the cereal cultivated soils globally contain low amount of plant available Zn

(Graham and Welch, 1996)

Zn

Zn

Zn

ZnZn

high CaCO3high pHclay soilslow organic matterlow soil moisturehigh Fe and Al oxides

Decreased Zn desorption

Zn

Zn

Zn

ZnEnhanced Zn adsorption

and precipitation

SOIL

Soil factors affecting availability of Zn to roots

LimitedZn uptake

Additional Cause of Zn Deficiency: Intensification of Farming Intensification of Farming

Zinc 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 Basic Roles of ZincZinc in in Biological SystemsBiological Systems

nearly 10 % of proteins needs Zn for their function nearly 10 % of proteins needs Zn for their function and structureand 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 Basic Roles of ZincZinc in in Biological SystemsBiological Systems

nearly 10 % of proteins needs Zn for their function and structure

structural and functional integrity of biological structural and functional integrity of biological membranes depends on adequate amount of Zn 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.

Amino acids, Sugars..

Zinc Deficiency-Induced Root Exudation

Pathogenic Attack

Pathogenic Attack

Basic Roles of Basic Roles of ZincZinc in in Biological SystemsBiological 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 ZZinc is a major actor of cellular defense systems against inc is a major actor of cellular defense systems against highly toxic oxygen free radicals ( better tolerance to highly toxic oxygen free radicals ( better tolerance to environmental stress factors, e.g., drought stress)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.

S-HS-H

MEMBRANE DNA PROTEIN

ZINC PROVIDES DEFENSE AGAINST FREE RADICAL DAMAGE IN CELLS

O2h.v. e-

LIPIDPEROXIDATION

PROTEINDAMAGE

MUTATION

CHLOROPHYLL

CHLOROSIS

S=S

1O2 O2

._

H2O2 OH.

S=S

CELL DEATH

ZINC IS NEEDED FOR DETOXIFICATION

OF FREE RADICALS

ZINC IS NEEDED FOR INHIBITION OF

RADICAL GENERATION

Cakmak, 2000; New Phytologist, 146: 185-205

Zn Deficiency Makes Plants Highly Sensitive to High Light and Heat

Partial shading of primary leaves of Zn-deficient bean

plants

Basic Roles of Basic Roles of ZincZinc in in Biological SystemsBiological 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)ZZinc is required for protection of IAA from inc is required for protection of IAA from oxidationoxidation Zinc is required for better pollination

Marschner, 1995; Cakmak, 2000, New Phytol.

Zn deficiency

less IAA synthesis

higher oxidative IAA degradation

Importance of Zinc for Auxin (IAA) Hormone

Evidence is available showing that Zn is involved in both biosytnhesis of IAA and also protection of IAA from oxidative attack by free radicals

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

M Shoot dry wt.

Zn

Free amino acids

IAA

+Zn (10-6)

g/plant

8.24

mg kg-1

52

µmol g-1 dry wt.

82

µg kg-1 fresh wt.

240

- Zn 3.66 13 533 122

Zn-Resupply 4.53 141 118 180

Cakmak et al., 1989, J. Experimental Botany, 40:405

Unde Zn deficiency IAA is Reduced

+Zn+Zn

-Zn-Zn

Reduced Shoot Elongation and Little Leaf Formation are very Characteristic for Zn deficiency

Apple, N-China

‘little leaf’

Basic Roles of Basic Roles of ZincZinc in in Biological SystemsBiological 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 pollinationZinc is required for better pollination

Marschner, 1995; Cakmak, 2000, New Phytol.

Zn supply Shoot Dry Weight (g/plant)

Grain yield (g/plant)

Pollen viability

(%)

Zn conc. in pollen

(mg/kg)

Adequate Zinc

74 70 85 75

Zinc Deficiency

67 18 20 27

Specific high Zn demand for pollination

Sharma et al., Plant Soil 124, 221-226; 1990

Effect of Zn supply on growth, grain yield, viability and Zn concentration of pollen in maize plants

Zinc Deficiency Zinc Deficiency Symptoms in Symptoms in

WheatWheat

Zn-adequate wheat leaf

Development of Zn deficieny in wheat

Development of Zn deficieny in wheat

Development of Zn deficieny in wheat

Zn deficieny in wheat

Zn deficieny in wheat

Severe Zn deficieny in wheat

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

Human Zinc DeficiencyHuman Zinc Deficiency

Zinc Estimated 2 billion

Micronutrient Deficiencies: Global Malnutrition Problem

www.harvestplus.org

Iron Estimated 2

billion

Zinc affects a Zinc affects a range ofrange of functions:functions:

• Immunity• Growth• Brain development • Reproduction•….

www.harvestplus.org

Human Zinc Human Zinc DDeficiencyeficiency

Moderate

Not sufficient data availableLow

High

http://www.izincg.org/

Widespread Zn Deficiency

Medium Zn DeficiencyAlloway, 2004. IZA Publications, Brussels

Soil Zinc DeficiencySoil Zinc Deficiency

Soil and Human Zn Deficiency: geographical overlap

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

IZA in partnership with UNICEF started a program called ‘Zinc Saves Kids’www.ZincSavesKids.org

Intl’ Zinc Assoc.

ZINC SAVES KIDSZINC SAVES KIDS

Major Reason:Major Reason: Low Dietary IntakeLow Dietary Intake High Consumption Cereal Based Foods with Low Micronutrient Concentrations

In number of developing countries, cereals contributes nearly 75 % of the daily calorie intake.

Solutions to Micronutrient Deficiencies

•Supplementation Supplementation •Food FortificationFood Fortification (not affordable in rural

regions)

Golden Wheat Fortfied with Zn

Agricultural Solutions(Breeding and Fertilizer Approaches)

•Breeding

•Agronomy/Fertilizers

HarvestPlus-Biofortification Challenge Program

Breeding new cereal cultivars with new cereal cultivars with high micronutrient content in high micronutrient content in cereal cereal graingrainssCoordinating Institutions: International Food Policy Research Institute (IFPRI)Washington DC and CIAT-Colombia

Main Sponsors: Gates Foundation and World Bank

www.harvestplus.org

www.gatesfoundation.org

“Two billion people in the developing world suffer from diets lacking 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 lower birth weight, a decrease in cognitive development, and increased susceptibility to other diseases.”

Main Sponsor of HarvestPlus Program

Application of Zinc Fertilizers: Application of Zinc Fertilizers: (Agronomic Biofortification)

Rapid and Sustainable Solution

Application of Zn-containing fertilizers offers a rapid solution to the problem

2011 June- 2014 May

Global Zinc FertilizerGlobal Zinc Fertilizer ProjectProjectII. PhaseII. Phase

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...Thank you...

Staining/Localization of Zinc in Wheat Grain (red color)

EMBRYO

ENDOSPERM

ALEURONE

ALEURONE

Cakmak et al., 2010

Cereal Chemistry, 77: 10-20

LA-ICP-MS Tests on Seeds

0100200300400500600700800900

1000

0 500 1000 1500 2000 2500 3000 3500 4000

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 500 1000 1500 2000

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

Cakmak et al., 2010,

J. Agric. Food. Chem.

White arrow: Zn in entire cross section

Black arrow: Zn in endosperm section

entire cross section

endosperm section

0200400600800

100012001400160018002000

0 500 1000 1500 2000 2500 3000 3500 4000

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

0200400600800

100012001400160018002000

0 500 1000 1500 2000 2500 3000 3500

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/Kg

)

0200400600800

100012001400160018002000

0 500 1000 1500 2000 2500 3000 3500

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

0

5

10

15

20

25

0 200 400 600 800 1000 1200 1400 1600

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

0

5

10

15

20

25

0 500 1000 1500 2000

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/kg

)

0

5

10

15

20

25

0 200 400 600 800 1000 1200 1400

Distance (µm)

Zn

co

nce

ntr

atio

n (

mg

/Kg

)

No Foliar Zn Application

Foliar Zn Application at Stem Elongation and Booting Stages

Foliar Zn Application at Milk and Dough Stages

B

cr

cr

cr

Endosperm

Endosperm

Endosperm

LA-ICP-MS Tests

Cakmak et al., 2010, J. Agric. Food. Chem. 58:9092-9102