biofortification of rice

BIOFORTIFICATION OF RICE

FOOD BIOTECHNOLOGY

PRESENTATION

BY

EUGENE MADZOKERE

4.1 Biotech Undergrad Student

Chinhoyi University of Technology (Zim)

PRESENTATION OUTLINE

INTRODUCTION:

-What is Biofortification?

-Reason for Rice Biofortification

-Micronutrients Biofortified into Rice

-Methods used to Biofortify Rice

-Where Biofortification is done? TYPES OF RICE BIOFORTIFICATION IN DETAIL:

CONCLUSION:

Advantages & Disadvantages? REFERENCES:

INTRODUCTION:

Biofortification: “The development of

nutrient dense staple crops using the best

traditional breeding practices and modern

biotechnology”.

It makes foods more nutritious as plants

are growing rather than having nutrients

added to plant foods during processing.

Reason for Rice Biofortification

Rice is a staple food crop for more than one billion poor people

The Rice endosperm (starchy & most edible part of rice seed) is deficient in many nutrients including vitamins, proteins, micronutrients, EAAs, etc.

The Aleurone layer of dehusked rice grains is nutrient rich but is lost during milling and polishing

Unprocessed rice becomes rancid i.e. smelly or unpleasant in taste

STRUCTURE OF THE RICE SEED GRAIN

Micronutrients Biofortified into Rice:

Vitamin A (Retinol) – Golden Rice

Iron

Zinc

Vitamin B9 (Folic acid/ Folate)

Glycinin

Methods used for Rice Biofortification:

Agrobacterium mediated gene transfer

Particle gene gun method

Where is Biofortification done?

India

China

USA

Phillipines

Vietnam

Bangladesh

Japan

Vitamin A Rice Biofortification:

Done by Prof. Ingo Potreykus & Dr. Peter Beyer

Because the rice endosperm lacks vitamin A and;

Vitamin A deficiency causes night blindness; impaired vision, epithelial tissue integrity, immune response; hematopoiesis & skeletal growth mostly in young children aged 1-5 years old

Biofortification involved introduction of three genes in rice grain via Agrobacterium tumefaciens:

1. phytoene synthase (psy) – daffodil (Narcissus pseudonarcissus)

2. lycopene B - cyclase (crt) – daffodil (Narcissus pseudonarcissus)

3. phytoene desaturase – bacterium (Erwinia uredovora)

Vitamin A Rice Biofortification:

Successful production of Golden rice 1 (GR1) and Golden rice 2 (GR2)

GR1- yield of 1.6µg provitamin A/g in endosperm

GR2- higher yield of 31µg/g provitamin A in endosperm by replacement of psy gene from daffodil with a psy gene from maize

72µg of GR2 could provide the recommended daily vitamin A allowance for 1-3 year olds, because they consume 100-200g of rice per meal.

GGPP (C20)

Phytoene (C40)

C-Carotene

Lycopene

B-carotene

Vitamin A

Phytoene synthase

Phytoene desaturase (PDS)

Zeta carotene desaturase

(ZDS)

CRT 1

Vitamin A Biofortification: Engineering

The Carotenoid Biosynthetic Pathway

Lycopene β- cyclase

Iron (Fe) Biofortification of Rice:

Iron (Fe) is a redox - active constituent of the catalytic site of heme and non-heme iron proteins

Metabolic functions of Fe include:

1. Serving as an element in blood production

2. Serving as a component of enzymes involved in synthesis of collagen & some neurotransmitters

3. Providing a transport medium for electrons within the cells in the form of cytochromes

4. Being a structural component of haemoglobin

Iron Biofortification of Rice:

Consequences of Fe deficiency include:

1. Blood loss leading up to Sickle Cell

Anaemia

2. Causes Gastro-intestinal blood loss in

men & post-menopausal women

Normal RBC Sickled RBC

Iron Biofortification of Rice:

In the Fe-Rice Biofortification process;

1. Three genes were introduced into the Japonica rice variety:

a) Ferritin – enhances iron storage in grains & was expressed under an endosperm specific promoter.

b) Nicotianamine synthase – was expressed under a constitutive promoter & produces nicotinamine which chelates iron temporarily facilitating its transport in plants

c) Phytase – degrades phytate

Zinc Biofortification of Rice:

Zn is an important micronutrient:

1. Critical in tissue growth, wound healing, connective tissue growth & maintenance, immune system function, prostaglandin production, bone mineralization, proper thyroid function, blood clotting, cognitive functions, fetal growth & sperm production

2. It plays an important role in the health of skin, bones, hair, nails, muscles, nerves & brain function.

3. Is required for metabolic activity of enzymes (as a cofactor) involved in repair & replacement of body cells.

4. Its essential for cell division & synthesis of DNA & proteins


Zn deficiency leads to:

1.Impairment of physical growth, immune

system & learning ability

2.Fetal brain cell disease & affects mental

development in pregnant mothers

3.Hindered normal growth and

development in children

4.Increased risk of infections, DNA damage

& cancer


In the Zn-Rice Biofortification process;

• Three (3) genes of the OSNAS family were introduced into Japonica rice cultivar Nipponbarp

• These three genes encode production of nicotianamine (NA) - a chelator of transition metals that facilitates uptake & transport of metal cations including, Zn2+

• Specific over-expression of OSNAS resulted in significant increase in NA concentration and Zn

• OSNAS 2 activation had 20 fold more NA & 2.7 fold Zn in polished rice grains

• OSNAS 3 activation was reported to reverse signs of Fe-deficiency when fed to anaemic mice

Folate Biofortification of Rice:

Folates (vitamin B9) are tripartite molecules

containing the pterin moiety, PABA, & one or

several Glutamate residues

It plays a major role in the methylation & in

DNA biosynthesis

Biofortification is achieved by over-

expressing 2 Arabidopsis thaliana genes of the

pterin and para-aminobenzoate branch of the

biosynthetic pathway from a single locus


Folate biosynthesis requires the plastid

chromate pathway intermediate (PABA) &

Pterin precursor from GTP

Rice engineered using targeted expression

of GTPCHI & ADCS to increase folic acid

biosynthesis in seeds

Transformed plants with ADCS had 49

fold increase in levels of PABA


Folate dietary deficiency results in :

1. Neural tube defects e.g. Spina bifida

2. Cardio vascular diseases

3. Different forms of dementia

4. Megaloblastic anaemia

Glycinin Biofortification of Rice:

Glycinin is a lysine rich globulin protein

found in soybean seeds

Lysine is an essential amino acid (EAA)

Rice seed endosperm is deficient in lysine

Glycinin accounts for more than 20%

seed dry weight & is a reserve for carbon

& nitrogen used in seed germination

Five Glycinin genes: Gy1; Gy2; Gy3; Gy4; &

Gy5


Four molecular approaches that are commonly used:

1. modifying the higher protein sequence of a major crop protein to contain higher content of desired EAA

2. Producing a synthetic protein rich in target EAA

3. Expressing a heterologous protein with high content of desired EAA

4. Manipulating the expression of a homologous protein for desired EAA

5. By increasing the pool of a specific free EAA through metabolic engineering


Approach 4 was used

Biofortification involved insertion of 4 contiguous methionine residues into the 11-S variable regions of the soybean Glycinin gene corresponding to the C-terminal regions of the acidic & basic polypeptides

Modified Met-rich soybean Glycinin gene under control of GluB-1 promoter was transformed using Agrobacterium tumefaciens and expressed in rice,

5% total glycinin protein was obtained


Mainly introduced because it is a seed storage protein which is lacking in the rice grain

Lysine facilitates normal growth & development; lowering of serum cholesterol; LDL cholesterol – hence lowered risk of heart disease

Effects of lysine deficiency include:

1. Hair loss or Poor growth

2. Excessive fatigue & mood changes

3. Loss of Appetite

4. Anemia

Supplements or food sources should provide 12mg/kg body weight of lysine/day

CONCLUSION: Advantages of

Rice Biofortification Advantages of biofortification of rice include:

1. Increase in nutritional value .i.e. bioavailable Vitamin A & B6; Fe; Protein (glycinine) & Zn

2. Increase in yield e.g. Rice biofortified with Glycine betaine for enhanced abiotic stress tolerance

3. Reduced adult & child micronutrient caused mortality

4. Reduced dietary deficiency diseases e.g. Blindness in children, diarrhoea, anemia

5. Healthier populations with strong and quick immune responses to infections.

CONCLUSION: Disadvantages of

Rice Biofortification Disadvantages of biofortification of rice include:

1. High production costs .i.e. equipment, technology, patenting, etc;

2. Potential negative interaction of biofortified rice on other plants/ non-GM rice crops causing loss of wild-type rice varieties

3. Low substantial equivalence- i.e. inability to provide high micronutrient and protein content compared to supplements

4. Poor rural populations have limited access & resources to purchase biofortified rice

5. Genetic engineering methods used may compromise immunity in humans .i.e. introduce increased risk of allergenicity

REFERENCES:

Sun, S.S.M., Liu, Q.Q. (2004). Trangenic

approaches to improve the nutrional quality

of plant proteins. In Vitro Cell Development.

Biology Plants. 40: pp. 155-162

Katsube, T., Kurisaka, N., Ogawa, M.,

Maruyama, N., Ohtsuka, R., Utsumi, S., and

Takaiwa, F. (1999). Accumulation of soybean

glycinin and its assembly with glutelins in

rice. Plant Physiology. 120: pp. 1063-1073