GOLDEN RICEGOLDEN RICE

Vitamin A enriched transgenicVitamin A enriched transgenic

Rice Rice

What is golden Rice?

• GM rice with 3 introduced genes

• Capable of b-carotene synthesis

• Golden yellow color kernels

Need for GR• VAD a major challenge

• Major cause of seeing disorders xeropthalmia to keratomalacia

• 124 million children affected worldwide

• 1 to 2 million deaths per year among children

• Prevalent in South and SE Asia where rice is a major food staple

VAD in women

• Night blindness is common among pregnant women

• Lactation deficiencies

• Maternal mortality up to 40%

Combating VAD

1.Dietary diversification

Common carotenoids

Plant sources

α carotene Carrots, palm oil

β carotene Green leafy veg, many fruits and sea weeds

γ carotene Fungi

δ carotene Tomatoes

2. Supplementation natural or artificial sources

3. Conventional fortification commonly consumed item-salt or

sugar

4. Fortification thro Genetic Engg. Golden Rice

Development of Golden Rice

• 1990 Gary Toeniessen realised lack of β carotene in polished rice

• Gene transfer for synthesis • Brainstorming session

Inventors

Daffodils

Gene transfer

Golden Rice

Erwinia uredovora

Gene Sources

Genes transferredGene Enzyme

codedSource

psy Phytoene synthase

Daffodils

ctrl Phytoene desaturase

Bacteria (Erwinia uredovora)

icy Lycopene β cyclase Daffodils

Beta Carotene Biosynthetic Pathway

GGDP

Tocopherols

Gibberellins

Chlorophyll

Phytoene

Phytoene synthase

(psy)

Phytoene desaturase (ctrl)

LycopeneLycopene β cyclase

(icy)

β Carotene

pB19hpc (Golden Rice Cassette)

TL TRaphIV 35S Gt1 psy 35S rbcS crtl

HygromycinResistance

PhytoeneSynthase

PhytoeneDesaturase

T-DNABorder

T-DNABorder

SelectableMarker

Gene ofInterest

Gene ofInterest

InsertionSequence

InsertionSequence

Difficulties

•Transfer of 3 genes•Transformation and

regeneration problems•Many patents (70)•Funding

Mile Stones• Selection of daffodils

• Transformation and regeneration protocols (Winn 1996)

• Transformants with phytoene (Burkhardt et al. 1997)

• Agrobacterium based transformation system for many genes (Ye et al. 2000)

Golden Rice (Potrykus et al 2000)

Testing the transformants

• HPLC tests used

• Transformed lines detected beta carotene, lutein, and zeaxanthin

• 1.6 µg/g β carotene detected (T309)

Accomplishments

• Biochemical manipulation thro genes (C3 to C4)

• Simultaneous gene transfer possible

• Biotech for poorest of poor

Benefits of G. Rice

• Sustainable and cost free solution for VAD

• No additional inputs• Seeds can be resown• Local varieties can be converted • Free for developing countries

Controversies

• GR is first generation GM crop

• Amount of b-carotene expressed (1.5-1.8 µg/g) is low

• Genetic erosion due to monoculture

• Other problems associated with any other GM crop (stability, silencing and unpredictable products)

Challenges ahead

• Resynthesis thro latest technology• Gene transfer to tropical local

varieties• Level of expression • Technological improvements• Nutritional studies essential

Golden Rice deserves a chance

Thank you