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Genetic Engineering of “Golden Rice”
Presenter: Meng Li
Background Information
• The inventors of Golden Rice were Ingo
Potrykus, Professor emeritus of the
Institute for Plant Sciences of the Swiss
Federal Institute of Technology, and
Professor Peter Beyer, of the Centre for
Applied Biosciences, University of
Freiburg, Germany
• The research for a Golden Rice started
off as a Rockefeller Foundation initiative
in 1982.
http://fic.osu.edu/initiatives/biomedical-nutrition.html
Background Information
• Vitamin A is essential for eye health and
the proper functioning of the immune
system.
• It is found in foods such as milk, liver,
eggs, red and orange fruits, red palm oil
and green leafy vegetables.
• Vitamin A deficiency (VAD) is prevalent
among the poor whose diets are based
on rice sources. Rice does not contain
any β-carotene (provitamin A) in grain.
• VAD could caused night blindness,
complete blindness, and affecting on
immune system.
http://fic.osu.edu/initiatives/biomedical-nutrition.html
Background Information
• In 2012 the World Health
Organization reported that
about 250 million
preschool children are
affected by VAD.
• Yearly, half a million
people—mainly children—
become blind as a
consequence of VAD, 50
percent of which die within
a year of becoming blind.
http://www.childinfo.org/vitamina.html
WHO
The Golden Rice Project
• The goal is to provide the
recommended daily
allowance of vitamin A
(600µg) in 100-200g of βcarotene-containing rice.
• A prototype Golden Rice was
developed in 1999, and new
lines with higher β-carotene
content have been
generated.
• Golden Rice grains are easily
recognizable by their yellow
to orange color, the stronger
the color the more βcarotene.
http://www.goldenrice.org/index.php
Achieve the Goal
• Rice produces β-carotene in the
leaves but not in the grain, where
the biosynthetic pathway is turned
off during plant development.
• Two genes have been inserted into
the rice genome by genetic
engineering, to restart the
carotenoid biosynthetic pathway
leading to the production and
accumulation of β-carotene in the
grains.
http://www.goldenrice.org/index.php
Genetic Engineering
• To produce Golden Rice, 2 enzymes
are introduced into the endosperm
[phytoene synthase (psy) and
phytoene desaturase (crtl)] via an
endosperm-specific glutelin (Gtl)
promoter, to establish a b-carotene
biosynthetic pathway in the rice
grains.
http://upload.wikimedia.org/wikipedia/commons/3/32/Carotenoid.svg
Golden Rice
• The first generation of Golden Rice is SGR1 (1999)
• SGR1 contained the phytoene synthase (psy) gene from
daffodil and the carotene desaturase (crtI) gene from the
bacterium Erwinia uredovora
• Both genes were expressed only in the rice endosperm.
• The carotenoids level in field production of SGR1 were up to
1.6 µg/g
http://www.goldenrice.org/Content2-How/how1_sci.php
• Gene construct used to generate SGR1. RB, T-DNA right border
sequence; Glu, rice endosperm-specific glutelin promoter;
tpSSU, pea ribulose bis-phosphate carboxylase small subunit
transit peptide for chloroplast localisation; nos, nopaline synthase
terminator; Psy, phytoene synthase gene from Narcissus
pseudonarcissus (GR1) or Zea mays (GR2); Ubi1, maize
polyubiquitin promoter; Pmi, phosphomannose isomerase gene
from E. coli for positive selection (GR2); LB, T-DNA left border
sequence.
http://www.goldenrice.org/Content2-How/how1_sci.php
Golden Rice Today
• The bottleneck of SGR1 was the enzymatic activity of PSY.
• Golden Rice–2 was transformed with a construct containing a
phytoene synthase gene from maize and contains up to 35 µg βcarotene per gram of dry rice.
http://www.goldenrice.org/Content2-How/how1_sci.php
Testing the Performance of Golden Rice
• The first human test of Golden Rice-2 by Guangwen in China,
2012.
Experiment
• Golden Rice plants were grow hydroponically with heavy water
to generate deuterium-labeled β-carotenein in rice grains.
Golden Rice servings of 65–98 g (130–200 g cooked rice)
containing 0.99–1.53 mg b-carotene were fed to 5 healthy adult
volunteers with 10 g butter. Blood samples were collected over
36 d.
Results: results showed that the mean area under the
curve for the total serum response to deuterium was
39.9 µg·d after the Golden Rice dose.
β -Carotene derived from Golden Rice is effectively
converted to vitamin A in humans.
Questions about Golden Rice
• Biosafety: effect of the
genes if outcrossing
occurred
• Health Effects: food safety
• Financial support for poor
and developing countries
References:
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1. Peter Beyer, Salim Al-Babili, Xudong Ye and Ingo Potrykus, et al. 2002, Symposium: Plant Breeding: A
New Tool for FightingMicronutrient Malnutrition, The Journal of Nutrition, 132: 506s-510S.
2. Guangwen Tang, Yuming Hu, Michael A Grusak, and Robert M Russell, et al., 2012, b-Carotene in
Golden Rice is as good as b-carotene in oil at providing vitamin A to children, The American Journal of
Clinical Nurtion, 96: 658-64.
3. Guangwen Tang, Gregory G Dolnikowski, , and Michael A Grusak, et al., 2009, Golden Rice is an
effective source of vitamin A, The American Journal of Clinical Nurtion, 2009:89:1776-83