Golden Rice

Prof.  C Kameswara Rao

Introduction

At a New Delhi Biotechnology workshop on February 12, 2001, Professor Ingo Potrykus, Swiss Federal Institute of Technology, Zurich, announced that India will receive technology transfer for the production of Golden Rice, free of encumbrances and licence fee.   This news brought much cheer to into the hearts of many in the country, but most people are blissfully unaware of the stormy seas of controversies in which a handful of nascent seeds of Golden Rice are struggling to survive and to become global giving succour to many a poor.
Golden Rice is an important issue for countries like India.   Public awareness of the benefits of this product will help in preventing  repeats of what has been happening with Bt cotton in India.

What is Golden Rice?

Golden Rice is a transgenic variety of  rice, with genes for the synthesis of b-carotene taken from the temperate garden favourite Narcissus pseudonarcissus (daffodil) and inserted into the genome of a temperate strain of rice, using Agrobacterium tumefaciens as the vector, to effect the transfer.   The gene construct also contains some genes for enzymes of the biosynthetic pathway of b-carotene, from another bacterium  Erwinia uredovora.    The grains of this Genetically Modified (GM) rice  are similar to other varieties, in their  crinkly and scabrous husks but the core of the grain is pale yellow,  instead of pearly white.  The colour is due to b-carotene, which makes this the Golden Rice, more so because b-carotene is very important to our health.

The detailed technology used to develop Golden Rice was published by Potrykus and his associates, in Science (vol. 287,  pp 303-305, January, 2000). Ever since Professors Ingo Potrykus  and Peter Beyer (University of Freiburg, Germany) have announced their success in producing Golden Rice, about a year ago, there has been an incessant increasingly polarized public debate over the pros and cons of not just Golden Rice, but all GM crops and organic produce.   A number of websites are splitting at the seams with voluminous daily contributions of arguments, some of them being quite vitriolic. 
  
The Carotenoid Pool

About 600 structures of a group of chemical compounds called carotenoids have been discovered in various organisms, but predominantly confined to plants.  The carotenes are hydrocarbons, while the other carotenoids  also contain oxygen.  The carotenoids are insoluble in water but are soluble in fats and organic solvents.  

Several carotenoids occur simultaneously in organisms, and are in a continuous state of metabolic flux.   They are referred together as the carotenoid pool, the same way as the amino acid pool  and the nucleotide pool.  

 About 150 of the carotenoids are widely found, among which about 20 closely related carotenoids occur in a wide variety of higher plants,  sea weeds,  animals, fungi and bacteria.    Carotenoids are light harvesting pigments located in the plastids.   The carotenoids in the chloroplasts protect chlorophyll from damage by excessive light.
The carotenoids, related to and derived from b-carotene, impart pale yellow to light reddish yellow colour to the parts in which they occur.   Organisms contain different combinations and quantities of carotenoids in different parts.   Leaves and other green parts, anthers, pollen, styles and stigmas, fruits and seeds of several species of plants contain carotenoids.   Leafy vegetables, mangoes, peaches,  oranges, saffron, maize kernels, yellow-red  coloured pulses, carrots, beetroot, sweet potato, etc., are the common examples.  

 In the earlier days, the techniques of chemical analysis were not sophisticated enough to precisely distinguish one carotenoid from the other, and quantify them.   Hence most of the earlier literature collectively called them all carotenoids.    HPLC is now routinely used to isolate and quantify different carotenoid compounds.    The more important of the carotenoids and their sources are listed below:

a-carotene:  leaves and roots of carrots, and the fruit of red palm oil plant
b-carotene:  a very large number of plants and animals, abundant in brown sea
                      weeds but exceptionally high concentrations in the daffodils
d-carotene:   tomato fruits
g-carotene:   many flowers and fruits, but more abundant in the fungi
Lycopene:    tomato fruit
b-cryptoxanthin: maize seeds, eggs, butter, and blood.
Spirilloxanthine: photosynthetic bacteria and some fungi
Lutein (xanthophylls): flowers, fruits, seeds, eggs and animal fats
 
As humans and animals cannot synthesize carotenoids, they must be obtained from vegetable dietary sources. 
 
b-Carotene, Vitamin-a and our Health
b-carotene is extremely important to us as it is the  most efficient precursor of retinol  (vitamin-A), hence it is called pro-vitamin-A.   The liver converts b-carotene into vitamin-A, the only way we can get our requirement of vitamin-A.  Specific enzymes split one molecule of b-carotene into two molecules of vitamin-A.   
 
Deficiency of vitamin-A causes dry skin, dry eyes, dry mucous surfaces, retarded development and growth, sterility in males and night blindness and other types of irreversible blindness. Every year, at least a million children die weakened by vitamin-A deficiency and about 3,50,000 others go blind.   Millions of others, young and old, suffer from several disorders related to vitamin-A deficiency (VADs). 
 
Lycopene and lutein  do not yield vitamin-A.   a-carotene and   b-cryptoxanthin are converted into vitamin-A, but only one molecule of vitamin-A is formed from one molecule of these compounds, while the rest of the molecule adds to the chemical debris of the body.    Hence, maize kernels, eggs and animal fats like butter are poor sources of pro-vitamin-A, while tomato is no source at all.  
 
Disease Prevention By b-Carotene
In recent times, b-carotene has been rated high as an antioxidant which scavenges free-radicals, which are believed to be involved in the onset of several disorders, including cardio-vascular disease and certain types of cancer.    b-carotene is being increasingly used as a preventive measure against these diseases.
 
Our Sources Of b-Carotene
The rice plant produces b-carotene in the green tissues but there is none in the starchy endosperm which constitutes  90 per cent of the grain we eat.  Most of us get the required amount of b-carotene from supplementary food such as carrots, fruits and leafy vegetables.   Several communities, such as the Japanese, consume brown sea weeds, which are high in b-carotene.   
 
Throughout the world, the poor do not get enough of b-carotene and hence suffer from vitamin-A deficiency.   Vitamin-A deficiency may also be due to certain diseases like measles.  
 
Why Golden Rice?

About a dozen years ago, Gary Toenniessen, Director of Food Security, Rockefeller Foundation, has recognized the lack of b-carotene in polished rice and identified as a worthwhile goal,  the transfer of genes for b-carotene synthesis into food grains, particularly rice,  using transgenic technology.    Such a fine tuned task is beyond the possibilities of traditional plant breeding techniques to achieve.
 
Potrykus saw a hope for millions of poor children in introducing the gene for b-carotene in the rice itself, which is the staple food.   The synthesis of b-carotene in plants is a complex process controlled by several genes, which make the task of producing a transgenic much more difficult.  Peter Beyer, an expert on the biosynthetic pathway of b-carotene in daffodils, became an associate.   The choice of daffodils as the source of b-carotene genes is a very clever one, as they have an exceptionally high concentration of b-carotene, all of which can be converted into vitamin-A, but unfortunately no part of daffodils is edible.   
  
Synthesis of Golden Rice

Potrykus and Beyer faced several difficulties in creating Golden Rice, the more important being:
 
a) the transfer of a set of several genes together proved to be a formidable task;
 
b)  rice plants did  not grow well in green houses; and
 
c) the genes they transferred and the bacteria used for such transfer were encumbered 
    by patents and proprietary rights. 
 
Finally all the difficulties were overcome.   The success was achieved, more importantly,  without industrial financial support.  The owners of different patents, Syngenta, Monsanto and four other companies, recently agreed to donate the technology free to developing countries, in exchange for commercial marketing rights in the US and other affluent markets.   The concession offered by the patent owners is the basis for the announcement by Potrykus, at New Delhi,  on a free transfer of technology to India.   An appreciable gesture,  but sneered at by the Rural Advancement Foundation International, as “a rip-off of the public trust”.  
 
Challenges Ahead
A decade’s dream of Potrykus has been realised, but a lot more is yet to be done, the following being the more important challenges:
 
a) the gene set has to be transferred to a tropical variety of rice since the temperate
    variety will not fare well  nor will it be accepted, in the tropics;
 
b) years’ of lab and field work on perfecting a viable Golden Rice varieties suitable
    for  different agro-climatic zones of India, need to be developed; 
 
c) currently the quantity of b-carotene in the golden rice is not good enough to
    provide a substantial quantity of it, at the normal 300g of rice eaten per
    day; 
 
d) the product should be affordable to the very poor of the world, for which it should
    get into the Public Distribution System,  and 
 
e) the hostile, sometimes violent,   protestors have to be satisfied on the safety (some
   gene products may cause allergies, some GM crops are feared to become    gregarious weeds) and utility of the product (the ultimate desired  benefit may not be available in the end).  
 
Do GM Crops Become Threatening Weeds?
Amidst the disturbing controversy, an article in the journal Nature (February 8, 2001) came as a whiff of fresh air.   A ten year study in UK by Michael Crawley and team  has shown that GM crops hardier than rice, such as maize, beet, oilseed rape and   potato, did not become more competitive than their non-GM counterparts and did
not invade the environment 
 
Rice is a very delicate plant.   Golden Rice becoming gregarious is far beyond the realm of possibilities.
 
Fool’s Gold?
The Greenpeace organization, which is at the forefront of criticism of biotechnology products, posted a statement on the internet on February 9, 2001, and dubbed Golden Rice as ‘Fool’s Gold’.   The criticism is based on the following points:
 
a)      that the promoters of Golden Rice and supporters of GM crops have gone too far in over selling
          the product as for example by such statements as Syngenta’s projection that a single month’s
          marketing delay of Golden Rice will cause 50,000 children to go blind;
 
b)      an adult would have to eat 3.7kg of raw  (around 9kg of cooked) Golden Rice, as
          against the normal intake of 300g of raw rice a day,  to get the daily requirement 
          of b-carotene;  and    
 
c)      the underlying causes of vitamin-A deficiency (poverty and lack of access to more
          diverse diet) were not addressed and short term measures such as supplementation    
          (e.g., pills) and food fortification which are cheap and effective were not
          considered.
 
At a Press Conference on February 9, 2001, at Lyon, France, Ingo Potrykus conceded that the quantity of b-carotene available in the current sample of Golden Rice is small and needs to be improved.   He pointed out that it was never meant that Golden Rice alone would supply the entire daily requirement.   He assured that golden rice does not compete with alternative and traditional interventions but rather complements them.  
 
With the possibility of wheat, cassava, sweet potato, banana, etc.,  going gold in the future, alternatives to Golden Rice will be several.   The future crops will also address other deficiencies such as iron, essential amino acids, etc.
 
Some Points To Ponder
Amidst these emotionally charged, and seemingly uncompromising positions of the protagonists  and antagonists of GM crops, we should keep in mind certain issues, particularly in the context of Golden Rice.
 
The concept of balance diet has come into practice as people have realised a very long time ago that no single (or even a few) food items can provide all the nutrients we need.     Potrykus says that Goldeb Rice can now provide 20-40 per cent of the daily requirement.   Those who eat Golden Rice would get at least some b-carotene, which certainly will compensate marginal deficiencies.
 
There is no dearth for sources of b-carotene in most countries.    There are about 160 species of plants in India, used as food and/or medicine, which contain very considerable amounts of b-carotene in their carotenoid pool.   The red and green amaranth leaf vegetable contains 14.2mg/100g and the leaves of colocasia (taro) contain about 12.00mg/100g, higher than in carrot (8.7mg), beetroot (5.8mg), and spinach (5.5mg).   Curry leaves (7.5mg) and coriander leaves (6.9mg) compare also very well, with the well known western sources of b-carotene.   Even considering that all these plants contain may not exclusively be b-carotene, and that these quantities may vary from place to place in the same item, one can obtain the 5mg as the day’s requirement from most of these.   But can one eat a 100g of  any single one of these items and every day?  
 
Greenpeace suggested supplementation through pills.   As purified b-carotene is expensive costing  about US $ 185/25mg, administration of the recommended dose (5mg/day) through pills  is not feasible. 
 
Greenpeace suggested red palm oil as a source of pro-vitamin-A, but what this contains abundantly is a-carotene, which is only half as efficient as b-carotene in terms of conversion into vitamin-A.   Besides, palm oil contains about 48 per cent of palmitic acid, a saturated fatty acid, which is not so good for our health.   Then, how much of palm oil one can consume?   How much of it actually is available to the poor who cannot afford even the more commonly available leafy vegetables?
 
Vitamin-A requires a (mostly endogenous) protein and palmitic acid to be stable and functional in our body.   It also requires tocopherol (vitamin-E), an antioxidant that makes it more stable.   When these substances are not present in the existing varieties of rice and other cereals, it is very unreasonable to expect Golden Rice to contain them.   May be if given a chance, the future varieties of Golden Rice may contain these stabilising compounds.   Their absence does not make Golden Rice a useless product.
 
Golden Rice is now only a research product and it takes a lot of time and effort to make it available across the counter, particularly in the developing countries,  which essentially require it.    Controversial issues can be settled only through relevant experimental data and discussion
 
We are aiming the benefits of Golden Rice at the poorest of the poor who cannot get anything other than rice, green chillies and salt, if at all.   Traditional wisdom taught all communities to eat adequate quantities of pulses, green vegetables and fruits.   But affordability, not availability,  is the problem.   Even when Golden Rice is on the market, affordability will be the spoiler, though free technology transfer is a blessing.   Even those who can afford supplementary foods do not often get adequate quantities of b-carotene, for various individual metabolic deficiencies or merely out of ignorance.  Just as the compulsory use iodised salt, even by those who do not need it, has been introduced so that those needing iodine would get it, Golden Rice too will provide for a compulsory intake of some quantity of b-carotene.   This is to save millions of children in the developing world, from blindness and death.
 
High Security for Biotechnology?
In a civilised society hooliganism and vandalism have no place.   Destroying or burning GM trial plots, vandalising research laboratories are abominable criminal acts, which transgress the intellectual and material property rights of others.     Discussion and not destruction is the need of the hour.  The degree of scare implanted by  biotech antagonists on the minds of biotechnology researchers, is reflected by the fact that Golden Rice seeds are protected in a grenade proof bunker  in Switzerland!

Dr C Kameswara Rao,
Postgraduate Department of Applied Botany and Biotechnology, SSMRV College, Bangalore 560 078, and Executive Secretary, Foundation for Biotechnology Awareness and Education, No. 1,  Gupta’s Layout, Southend Road, Bangalore 560 004.   Res. Ph.: 080-6549470;  E-mail.:krao@vsnl.com