Metabolic Engineering Class (Professor Dinesh Chandra Agrawal) 03 - 01 - 2020

2. History
of
Golden
Rice
The problem of
Vitamin A
Defisiensi and
Problem Solving
Genetic
modified
Metabolic
Pathway to
Develop Vitamin
A
GR 1 and
GR 2
Controv
ersy
Against
“Fool’s
Gold”
Concluti
on

3. HISTORY OF GOLDEN RICE
 Started in 1981 by Ingo Potrykus-Professor emeritus of the
Institute for Plant Sciences and Peter Beyer-Professor of Centre for
Applied Biosciences, Uni. Of Freiburg, Germany. Funded by the
Rockefeller Foundation, the Swiss Federal Institute of Technology,
and Syngenta, a crop protection company.
Vrije Universiteit Brussel (www.vib.be)
2019 = Government of the Philippines on 10th December 2019,
authorized the direct use of Golden Rice (GR2E) in food, feed, and
for processing. Philippines become the first Asian country to do so.

4. Iron Deficiency Anemia (IDA) &Vitamin A
Deficiency (VIA)
 In Africa and Asia UNICEF estimates that IDA contributes to approximately 20
per cent of all maternal deaths. Heme iron, which is relatively well absorbed by
the human intestine, is found primarily in foods containing blood and muscle.
 Each yearVAD is also the single most important cause of blindness among
children in developing countries, about 500,000 per year. As the major staple
food, rice plants do not produce carotenoid compounds in the grain as
consumed by humans, consequentlyVAD often occurs.
 Director General of the International Food Policy Research Institute, has
pointed out that a sustainable solution of the problem will come only when it
will be possible to improve the content of the missing
micronutrients in the major staple crops.

5. GOLDEN RICE AS A SOLVINGTHE
SCIENTIFIC PROBLEMS.
 As rice endosperm did not contain any provitamin A, the task
was to introduce the entire biochemical pathway.
 31 march 1999, scientist present the endosperm contained good
quantities of provitamin A, beautifully visible as "golden"
color of different intensity in different lines.The best
provitamin A line had 85% of its carotenoids as beta-carotene.
 β-carotene is a very effective antioxidant and is suspected to
reduce the risk of cancers known to be initiated by the
production of free radicals.
 In 2001 Lucca et al said thatThe three "iron genes" are combined with the
"provitamin A genes" by crossing. Vitamin A supply is strategy against iron
deficiency. Vitamin A deficiency indirectly affects iron
resorption.

6. GOLDEN RICE AS A SOLVING THE
SCIENTIFIC PROBLEMS.
 Bio-fortification, a type of micronutrient intervention, aims to
increase micronutrients in seeds, tubers, and leafy vegetables of
food crops, and has the potential to reach the rural poor more
effectively, the group who are often at highest risk of
micronutrient deficiencies (Hotz and McClafferty, 2007)
 Golden rice equally strongly opposed by the opponents of
genetically modified organisms (GMOs). It is an excellent
example of how genetic engineering of plants can be of direct
benefit to the consumer.

7. HOW DOES IT WORK?
 The addition of 2 genes in the rice genome
will complete the biosynthetic pathway
 1. Phytoene synthase (psy) – derived
from daffodils
 2. Lycopene cyclase (CRT1) – from soil
bacteria Erwinia uredovora
 Produces enzymes and catalysts for the
biosynthesis of carotenoids (β-carotene) in
the endosperm of the grain and fully active
in leaves.
Presence of pro-vitamin A gives rice grains a yellowish-orange color, thus, the
name ‘Golden Rice’.When the rice is consumed, the β-carotene is either
stored in the fatty tissues of the body or converted into vitamin A.

8. GENETIC MODIFIED
Vrije Universiteit Brussel (www.vib.be)
Cutting the gene at the recognition sites Polymerase chain reaction
Insertion of the desired recombinant DNA into
the host organism.

9.  carotenoid biosynthesis begins with a
small (C5) compound,
isopentenyldiphosphate (IPP) and its
isomer dimethyl ally-diphosphate
(DMAPP).
 Chain elongation by C5 units leads to
the formation of the C20-compound
geranylgeranyl-diphosphate (GGPP).
 GGPP is a precursor that can enter
several biosynthetic routes, as indicated.
The head-to-head condensation of two
GGPP molecules produces the first,
colorless carotene, phytoene.
 A series of desaturation reactions lead
to the colored chromophore of
lycopene, and subsequent cyclization
reactions produce the β- and ε-ionone
rings.
 Oxygenation (hydroxylation,
epoxidation) reactions lead then to
xanthophyll.
 Several known pathways branch off at
this point, forming biologically
important molecules, such as abscisic
acid and strigolactones
Metabolic Pathway to Develop Vitamin A

10.  Pathway elements in green are functional
in wild-type rice grains.Thus the GGPP
precursor molecule is being synthesized
and lycopene can be cyclized.
 Elements in blue, including the blue box,
are effectively absent.
 Introduction of the enzymes phytoene-
synthase and the bacterial desaturase
CRTI fills the biosynthetic gap created by
the absence of the blue elements. Metabolic Pathway to Develop
Vitamin A

11.  The Golden Rice Project is being moved forward at various levels. After
the Golden Rice prototype obtained in the year 1999 (Ye et al. 2000) and
which accumulated around 1.6 μg/g of β-carotene in the grain, new lines
were generated by using gene construct with tissue-specific promoters.
 This led to the first Golden Rice (GR1), which produced up to an
average of 6 μg/g of βcarotene.
 The most advanced version of Golden Rice was produced by Syngenta
scientists (Paine et al.2005) and has been coined GR2. This improved
version produces 31 μg/g and more β-carotene, which is more than
enough to supply the required amounts of β-carotene, according to the
bioavailability results.

12. Golden Rice colors. (a)Wild-tape rice; (b) GR1, expressing the phytoene
synthase from daffodil along with CRTI; (c) GR2 expressing the phytoene synthase
from maize along with CRTI. Photograph courtesy of Aron Silverstone.

13. CONTROVERSY AGAINST “FOOL’S GOLD”
Health
 May cause allergies or fail to perform desired effect
 Supply does not provide a substantial quantity as the
recommended daily intake
Environment
 Loss of Biodiversity. May become a gregarious weed and
endanger the existence of natural rice plants
 Genetic contamination of natural, global staple foods
Culture
 Some people prefer to cultivate and eat only white rice based on
traditional values and spiritual beliefs

14.  Children 1–6 years old are reported to have intakes of about 100–200mg
RE/day, signs of VAD do occur; in southern India these signs were relieved and
risk of mortality was reduced when the equivalent of 350–400mg RE/day was
given to children weekly .
 recommended safe intakes for adults are also extrapolated from those derived
for late infancy, i.e. 4.8 and 9.3mg RE/kg body weight/day
 Golden Rice contain 6 - 31 mg/kg of β-carotene or 1.0 - 5.2 mg RE/kg. So only
a small quantity of Golden Rice is enough to avoidVitamin A Deficiency, it
would not be a replacement but a complement to existing efforts to tackle the
problem.
1 mg retinol = 1 RE
1 mg β-carotene = 0.167 mg RE
(FAO report 2004)

15. CONCLUTION
 Golden Rice technology is based on the simple principle that rice plants
possess the whole machinery to synthesise β-carotene, and
while this machinery is fully active in leaves, parts of it are turned off in
the grain. By adding only two genes, a plant phytoene synthase
(psy) and a bacterial phytoene desaturase (crt I), the pathway
is turned back on and β-carotene consequently accumulates in the grain.
 As the major staple food, mixing standard rice with golden rice are
recommended solution to avoidVitamin A Deficiency.

16. Thank
You