GOLDEN RICE. A possible end to vitamin A deficiency.

BACKGROUND.

hundreds of millions of people are starving and suffering from micronutrient malnutrition.

Using genetic engineering technology, we have the potential to prevent this.

Every day 24,000 people die because of poverty-based lack vitamins, minerals and essential amino-acids.

BACKGROUND.

the majority of the world’s poor try to survive on staple foods.

Rice, for example, is the basic staple crop for half the humankind.

VITAMIN A DEFICIENCY.

• VAD for short • Responsible for around one to two

million deaths worldwide.• Five hundred thousand cases of

blindness• Fifty percent of individuals who became

blind die within a year.• Impacts the immune system.

VAD

coronary heart disease. certain cancers (e.g., cancer of the lungs,

prostate, etc.) various childhood diseases which result in

death (e.g., due to a weakened immune system).

childhood blindness (estimated to afflict 350,000 - 500,000 children per year).

macular degeneration, a leading cause of blindness in older people.

GOLDEN RICE

Designed to produce beta carotene. Precursor to vitamin A. Normally not found in rice. Problematic because places such as

Bangladesh, 80 percent of people’s energy intake comes from rice.

CHALLENGE.

Until then, only single gene transfers had been done.

The entire biochemical pathway, from geranyl-geranyl-pyrhophosphate, to beta-carotene had to be engineered.

Final goal to produce beta-carotene in rice endosperm.

GOLDEN RICE.

Ingo Potrykus and Peter Beyer. Utilized Agrobacterium tumefaciens bacteria

to genetically engineer rice plant. ‘T-DNA’, part of the tumor-inducing (Ti)

plasmid of the soil bacterium, Agrobacterium.

The Ti plasmid naturally invades plant cells, inserting the T-DNA into the plant cell genome, and causing the cell to develop into a plant tumor or gall.

The artificial gene construct is spliced in between the left and right borders of the T-DNA vector.

The borders of the T-DNA are ‘hotspots’ for recombination.

Ultimately why the vector can invade the plant’s genome and carry its hitch-hiker gene construct along with it.

ENZYMES.

• Psy (phytoene synthase) from daffodil • (Narcissus pseudo narcissus)• Crt1 (carotene desaturase) from the soil

bacterium Erwinia uredovora• Catalyze the biosynthesis of beta-carotene from

geranyl-geranyl diphosphate.• The insertion of a lyc (lycopene cyclase) gene was

thought to be needed, but research showed it was already being produced in wild-type rice endosperm

1. Phytoene synthase- from daffodil (narcissus) which converts geranylgeranyl-diphosphate into phytoene.

2. "CRTL" gene- from Erwinia uredovora, which codes for phytoene desaturase, which causes the rice plant to convert phytoene (a "light harvesting" carotenoid involved in photosynthesis) into lycopene (a carotenoid which is then utilized by the rice plant in the production of beta carotene).

3. Lycopene beta-cyclase - from daffodil, which converts lycopene into beta carotene.

FINAL GENE CONSTUCT.

Ubi1, maize polyubiquitin promoter

Glu, rice endosperm-specific glutelin promoter to ensure that the gene was only expressed in the endosperm of the rice.

tpSSU, a small subunit transit peptide for chloroplast localization

Crt1 and Psy.

Pmi, phosphomannose isomerase gene from E. coli for positive selection.

Nos, as the terminator

The original golden rice was called SGR1, and under greenhouse conditions it produced 1.6 µg/g of carotenoids.

In 2005 researchers at the biotechnology company Syngenta. Created a variation on golden rice

Golden rice 2 produces 23 times more carotenoids than golden rice.

Golden rice was developed to provide a low cost vitamin supplement in countries with individuals suffering from vitamin A deficiency.

Vitamin A supplementation programs take place internationally through pills and injections.

No single (or even a few) food items can provide all the nutrients we need.    

Golden Rice can now provide 20-40%of the daily requirement of vitamin A

The United Nations (UNICEF) estimates that 1 to 2 million deaths of children age 1-4 years old could be prevented annually around the world.

References Ye X, Al-Babili S, Klöti A, Zhang J, Lucca P, Beyer P,

Potrykus I (2000) Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science 287: 303-305.

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http://www.goldenrice.org/Content2-How/how1_sci.html>   the golden rice scandal unfolds <

http://www.i-sis.org.uk/goldenRiceScandal.php>