Reading the rice genome starts a new chapter in food science


The world's rice growers, who cover 11% of the world's arable land surface with their crop, giving half of the world's population 80% of their diets, have struck lucky with a fluke of nature. The genome of rice is the smallest of all those of the cereal crops, less than 1% of the wheat genome, for example, but it is similar enough to wheat and other rich- world crops that companies and research institutes have been racing to sequence it. Some scientists have called it the "Rosetta stone" for cereals, after the ancient stone inscribed in three languages that allowed historians to read Egyptian hieroglyphics for the first time. And in April separate publications in Science by the Swiss-based company Syngenta, and the Beijing Genomics Institute (BGI) and others, read out most of the rice Rosetta stone.

The result: the draft sequence of most of rice's 430 million base pairs along its 12 chromosomes. Monsanto had produced an earlier draft of 60% of the rice genome, but these results - using a quicker, rough draft technique called "whole genome shotgun" leave those data standing, along with those of the International Rice Genome Sequencing Project (IRGSP).

Syngenta have sequenced Oryza japonica, and the BGI has sequenced Oryza indica, which together cover most Asian rices, and are similar to the rices of Africa and America.

Not only that: although a private company, Syngenta has promised to collaborate with the International Rice Research Institute (IRRI) in Manila during the crucial 10-year process of "functional mapping" of the genome. During this time the raw data are turned into a sequence of clearly identified functional genes. The BGI has already made its data freely available worldwide.

Ron Cantrell, Director of IRRI, told the Bulletin "we would like to encourage Syngenta to share their data freely with as many public researchers working in the developing world as possible. While their genomic data may not be merged with our own genome database, it should still be able to be accessed independently by rice scientists in resource-poor countries. It will then be up to researchers to make sense of all the rice genome databases that now exist - Syngenta's, BGI's, Monsanto's, and IRGSP's."

Cantrell said that while Syngenta's willingness to share at least some of its data should be recognized, he was keen to encourage the company to go further, adding that the firm was continuing to develop its approach to sharing the results of its rice research. He had been worried when he had first heard that the inventors of vitamin-A rich, genetically modified (GM) "golden rice" (Ingo Potrykus of the Institute for Plant Sciences, Swiss Federal Institute of Technology, Zurich, Switzerland, and Peter Beyer of the Centre for Applied Biosciences, University of Freiburg, Germany) had decided to involve Syngenta, in their quest to get this rice made available. "I thought, boy, that's going to really slow things down. At IRRI we had found that as we tried to deal with private companies, they didn't understand what we were trying to do. So I wasn't thrilled."

"But as the old story goes", Cantrell said, "I've come away with a different point of view. We've found Syngenta helpful in trying to work out all of the intellectual property issues in negotiating with this golden rice technology; they clearly understood the need for new technology to address issues of poverty, and I thought they were really trying to be helpful. So we have had a quite a positive experience with the company."

In fact, Syngenta can well afford to be generous with rice. It will make its profits from the application of the understanding - and genes - that it finds in rice to more profitable crops such as wheat, barley, and maize. All the cereal genomes, according to Science, "have the same genes in the same order", but the profitable ones seem to have more DNA, making their genomes so large it would have been impractical to sequence them. Wheat alone has a genome 16 billion base pairs long, an extraordinary five times the size of the human genome.

Scientists say a "Green Gene" revolution is now possible and needed to feed the world, but others are more sceptical. The last Green Revolution produced more food, but much of it didn't reach the people who most needed it.

According to a survey of the differences in nutrition during childhood - the most sensitive age - in 63 developing countries between 1970 and 1995 by the independent International Food Policy Research Institute, the following factors caused most of the improvements:

• level of women's education (caused 43% of the improvements);

• national per capita food availability (26%);

• health and environmental factors (19%);

• women's status in society (12%).

According to these figures, if improving rice productivity affected food availability it would contribute to 26% of the causes of improvement in child nutrition, whereas improving the status and education of women would more than double that effect (43% + 12% = 55%).

Understanding the genome may also make it easier to modify rice genetically to produce more micronutrients, but WHO's micronutrient specialist Bruno de Benoist points out that the first modified rice, golden rice, which produces vitamin A, still has a long way to go.

"It's still only available experimentally, and it produces far too little vitamin A" says de Benoist. Shortages of micronutrients are most important in pregnancy and very early childhood. But according to de Benoist a child would need to eat 1 kg of golden rice a day to meet its vitamin A requirement, or 300 g for a third of it. "And they should be eating vegetables as well - golden rice is unrealistic at the moment, compared to food supplements."


New rice for Africa to increase farmers' yields 50% - without fertilizer

Even without the new genetic knowledge, traditional rice crossing and back-crossing plus the biotechnological technique of "anther culture" has just produced a dramatic advance for Africa, according to the West African Rice Development Association (WARDA), based in Côte d'Ivoire.

In mid-April, amid the furore about the genetic sequencing of rice, WARDA announced that it had crossed the Asian Oryza japonica with African upland Oryza glaberrima rice varieties to produce a new rice that is yielding "up to 50% greater yield without fertilizer", Guy Manners of WARDA told the Bulletin, and at least double that "under improved management". Called NERICA (New Rice for Africa), the new variety also matures 30 - 50 days earlier than the currently grown varieties, he says.

According to The Independent newspaper of Banjul the new rice is also substantially richer in protein, more tolerant to disease, drought and acid soils, resists some of the most damaging insect pests in West Africa, and can out-compete weeds. "Because the rice was designed for resource-poor farmers, it can help farmers reduce poverty and save developing countries millions of dollars in rice imports" said The Independent.

Kanayo F. Nwanze, Director-General of WARDA, says "Ironically, rice was considered a luxury food in West Africa only two decades ago. Today, it's the staple." WARDA says rice now contributes more calories and protein than any other cereal in humid West Africa, and about the same as all roots and tubers combined. Moreover, demand for rice is growing faster in this region than anywhere in the world, with rice imports increasing eightfold over three decades, to over three million tonnes a year, at a cost of almost US$ 1 billion, says WARDA.

Will the new genomic knowledge help WARDA's future research? "A lot!" said Manners.



De Benoist also raises concerns about the potential allergenic effects of GM foods, and about the dangers of high-technology seeds causing poor farmers to become dependent on international seed companies.

But if all the potential problems with GM foods were solved, what should be the top health targets for molecular geneticists? "It depends on the region of the world" said Graeme Clugston, director of WHO's department of nutrition for health and development, "but top of the list must come vitamin A, lysine, iron and zinc".

Robert Walgate, Bulletin


World Health Organization Genebra - Genebra - Switzerland