GM approach to alleviate VAD

Golden Bananas
18
Aug
2017

GM approach to alleviate Vitamin A deficiency Disease (VADD)

Vitamin A deficiency (VAD) is considered to be one of the most harmful forms of malnutrition in the developing world. It can cause blindness, limit growth, and weaken the body’s immune system, thereby increasing morbidity and mortality. VAD is responsible for almost 6% of child deaths under the age of 5 years in Africa and 8% in South-East Asia, a condition that affects more than 140 million pre-school children in 118 nations, and more than seven million pregnant women[1]. VAD is prevalent among the poor whose diets are based mainly on rice or other carbohydrate-rich, micronutrient-poor calorie sources.

Golden Bananas

Stephen Buah & James Dale from QUT
©Erika Fish, QUT / Nat. Biotech

The Banana21 project aims to improve the nutritional content of bananas in Uganda, where the fruit is the major staple food in the daily diet[2]. Not all bananas lack vitamin A, but the ones they eat in Uganda do. For this purpose, the Queensland University of Technology in Australia have created using genetic modification a “Golden Bananas” that ups the beta-carotene content in the fruit by more than 30 times. The project led by Professor James Dale (QUT), had resulted in the identification and selection of banana genes that could be used to enhance pro-vitamin A in banana fruit. As a proof of concept, pro-vitamin A (PVA), PVA-biofortified transgenic Cavendish bananas were generated and field trialled in Australia with the aim of achieving a target level of 55 μg/g of dry weight (dw) β-carotene equivalent (β-CE) in the fruit. The Banana21 project is supported by the Bill & Melinda Gates Foundation backed with close to $10 million.

Golden Rice

Syngenta improved version “Golden Rice 2”

This is not the first attempt to overcome VAD using transgenic crop. The best-known example of biofortification by genetic modification and the most advanced in terms of development is ‘Golden Rice’. The project was led by Ingo Potrykus of the Swiss Federal Institute of Technology and Peter Beyer of the University of Freiburg was published early 2000[3]. However this originally Golden Rice only accumulated around 1.6 μg/g of β-carotene in the grain, which led to create an advanced version of Golden Rice that yield produces 31 μg/g and more β-carotene (up to 23-fold), which is more than enough to supply the required amounts of β-carotene, according to the bioavailability results. This improved version “Golden Rice 2”, coined GR2, was produced by Syngenta scientists[4] by combining the phytoene synthase gene from maize with crt1 from the original golden rice.

The approach of providing local farmers with modified crops, regardless of the technology used to achieve this and regardless of the social acceptance of these crops once on the market, may be one of the most efficient ways to create a self-sustaining cycle of nutritional independence and improved quality of life. Time will tell us how much success is in this!

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[1] Global health risks: mortality and burden of disease attributable to selected major risks. Geneva, World Health Organization, 2009. http://apps.who.int/iris/bitstream/10665/44664/1/9789241501767_eng.pdf

[2] Golden bananas in the field: elevated fruit pro-vitamin A from the expression of a single banana transgene. http://onlinelibrary.wiley.com/doi/10.1111/pbi.12650/full

[3] Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm”. Science. 287 (5451): 303–5. PMID 10634784. doi:10.1126/science.287.5451.303

[4] Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nat Biotechnol. 2005 Apr;23(4):482-7