From: XVI International Botanical Congress

New rices may help address vitamin A and iron deficiency, major causes of death in the developing world

    Genetically modified grain able to improve supply of iron and vitamin A in human diet -- lack of these nutrients is a major contributor to maternal and childhood death, disease and blindness in developing countries

St. Louis, MO, August 3, 1999 -- Researchers announced today that they have genetically modified rice grains to improve the supply of iron and vitamin A in the human diet. The genetically modified rices may help to reduce global rates of iron deficiency anemia (IDA) and vitamin A deficiency (VAD), especially in developing countries where the major staple food is rice. IDA and VAD are major contributors to childhood and maternal mortality and morbidity primarily in developing countries.

The research results were announced by Professor Ingo Potrykus at the XVI International Botanical Congress where more than 4,000 scientists from 100 countries are meeting to discuss the latest results of research on plants for human survival and improved quality of life. Professor Potrykus is a researcher with the Swiss Federal Institute of Technology's Institute for Plant Sciences. Professor Potrykus was the principal investigator for the two separate research teams conducting the vitamin A and iron research. The Rockefeller Foundation supported Professor Potrykus's vitamin A research.

IDA, the most common nutritional disorder in the world, impairs immunity and reduces the physical and mental capacities of people of all ages. In infants and young children, even mild anemia can impair intellectual development. Anemia in pregnancy is an important cause of maternal mortality, increasing the risk of hemorrhage and sepsis during childbirth. Infants born to anemic mothers often suffer from low birth weight and anemia themselves. An inadequate dietary intake of iron is the main cause of IDA.

According to UNICEF, nearly 2 billion people are estimated to be anemic and about double that number, or 3.7 billion, are iron deficient, the vast majority of them women. Between 40 and 50 per cent of children under five in developing countries -- and over 50 per cent of pregnant women -- are iron deficient. In Africa and Asia UNICEF estimates that IDA contributes to approximately 20 per cent of all maternal deaths.

Each year more than one million VAD-associated childhood deaths occur. And, according to the World Health Organization, as many as 230 million children are at risk of clinical or subclinical VAD, a condition that is largely preventable.

VAD makes children especially vulnerable to infection and worsens the course of many infections. Supplementation with vitamin A is estimated by UNICEF to lower a child's risk of dying by approximately 23 percent. VAD is also the single most important cause of blindness among children in developing countries.

The research into the new health-enhancing rice varieties received funding only from governments and not-for-profit organizations, including the Rockefeller Foundation, and will be freely available to national and international agricultural research centers. The International Rice Research Institute (IRRI), based in the Philippines, will be the researcher's immediate partner for further development of the transgenic material into publicly available rice breeding lines.

Rice plants do produce carotenoid compounds that are converted to vitamin A, but only in the green parts of the plant and not in the component of rice grain consumed by humans. Consequently VAD often occurs where rice is the major staple food. The millions of children who are weaned on rice gruels are particularly prone to VAD since they consume little else. And children in rural areas are seldom reached by vitamin A supplementation programs.

The amount of bioavailable iron is dependent both on the level of dietary iron consumption and on iron absorption during the digestive process. Dietary iron in developing countries consists primarily of non-heme iron of vegetable origin (e.g., unrefined cereals including rice, nuts, dark leafy vegetables), whose poor absorption is considered a major factor in the etiology of iron deficiency anemia. Also legume staples and grains, including rice, are high in phytic acid, which is a potent inhibitor of iron absorption. Foods that enhance non-heme absorption such as fruits and vegetables rich in ascorbic acid, are often limited in developing countries. Heme iron, which is relatively well absorbed by the human intestine, is found primarily in foods containing blood and muscle. Due to their expense and lack of availability, heme iron-rich foods are often only a negligible part of a typical developing country diet.

Dr. Potrykus and his collaborators achieved beta-carotene production in rice grain by adding three genes to rice plants, two from daffodil and one from the bacterium Erwina uredovora. The resulting transgenic rice plants produce sufficient beta-carotene -- converted to vitamin A in humans -- in the grain to meet total vitamin A requirements in a typical Asian diet. (see attached scientific abstract)

To increase the bioavailability of iron in the rice grain, the Swiss-based researchers increased the iron content and enhanced iron absorption. To double the iron content in rice, the research team added a ferritin gene derived from French bean. Ferritin is an iron storage protein found in many animals, plants and bacteria.

Iron absorption, which is inhibited by phytic acid found in the rice, was increased by introducing a phytase gene that degrades the phytic acid and by overexpressing the rice's own iron absorption-enhancing cysteine-containing proteins.

Following careful tests to determine the impact, if any, on the environment and human health and after acceptance by national biosafety authorities, the novel varieties of rice will be distributed free of charge by IRRI and various national agricultural research centers in developing countries. Local rice breeders, using traditional breeding techniques, would then transfer the characters of the beta-carotene and iron enhanced rice into varieties adapted to local conditions. Once in the possession of the farmer and plant breeder, the novel varieties become their unrestricted property. The farmers may, if they choose, use a portion of their harvests for further sowing.

The Rockefeller Foundation, founded in 1913, is a global foundation with a mandate and commitment to enrich and sustain the lives of the poor and excluded throughout the world. The work of the Rockefeller Foundation falls under four themes: food security, employment, health equity, creativity and innovation. The Foundation's president, Professor Gordon Conway, is a noted authority on agriculture in the developing world and author of The Doubly Green Revolution: Food for All in the 21st Century, a recently published book on global food security. Prof. Conway is the former vice-chancellor of the University of Sussex.

As part of its broader mission the Rockefeller Foundation has supported research into increasing crop yields of poor, smallholder farmers in developing countries profitably and without degrading natural resources. During the past 15 years, the Rockefeller Foundation has funded over $100 million of plant biotechnology research and trained over four hundred scientists from Asia, Africa and Latin America. At several locations in Asia there is now a critical mass of talent applying the new tools of biotechnology to rice improvement.

The Rockefeller Foundation's support of work in biotechnology builds on previous Foundation support of agricultural development in poor countries. For example, in 1970 the Nobel Peace prize was awarded to Rockefeller Foundation field scientist Norman E. Borlaug. Borlaug received the Nobel prize for his pivotal role in helping modernize agriculture in the developing world, an effort that became know as the 'Green Revolution.'

Research abstract: Contributions to food security by genetic engineering with rice

Ingo Potrykus, Paola Lucca, Xudong Ye, Salim Al-Babili, Richard F. Hurrel and Peter Beyer.

Institute of Plant Sciences, Swiss Federal Institute of Technology, ETH Centre, LFW E 32.1, CH 8092 Zürich. / Institute for Human Nutrition, Swiss Federal Institute of Technology, ETH Zürich, RUE D 15, CH 8092 Zürich. / Institute for Biology II, University of Freiburg, Schönzlestrasse1, D-79104 Freiburg.

The research team at the Institute of Plant Sciences led by Dr. Potrykus focuses on rice, wheat, sorghum and cassava and is using genetic engineering to contribute to the stabilization and increase of yield and to improvements in food quality. Two food quality examples with rice in the area of micronutrient deficiency exemplify the teams' research approach, which involves the Consultative Group on International Agricultural Research (CGIAR) system and free transfer of results to developing countries.

The major micronutrient deficiencies worldwide concern iron, with 24 percent of the world's population (up to 60 percent in developing countries) or 1.4 billion women suffering from iron deficiency anemia, and vitamin A-deficiency, affecting approximately 400 million children, or seven percent of the world population. The deficiencies are especially severe in developing countries where the major staple food is rice. To contribute to a solution of the problem, the research team set out to genetically engineer rice towards an improvement in supply of vitamin A and of iron to the diet. Iron-deficiency is the consequence of a) a very low amount of iron in the endosperm, b) a high concentration of phytate (the major cause for inhibition of iron resorption in the intestine), and c) lack of high sulfur-containing proteins enhancing iron resorption. Consequently Potrykus et. al aimed to a) an increase the iron content with a ferritin transgene from Phaseolus vulgare, b) reduce phytate in the cooked diet with a transgene for a heat-stable phytase from Aspergillus fumigatus and c) increase the resorption-enhancing effect from a transgenic sulfur-rich metallothionin-like protein from Oryza sativa. All transgenes are under endosperm-specific regulation. The researchers analyzed a series of transgenic rice plants for all genes mentioned and have achieved, so far, a twofold increase in iron content, and a high activity of the A. fumigatus phytase, reducing phytate completely after one hour of cooking. Expression of the metallothionin-like protein led to an increase in cystein of approximately 25 percent above control. (Paola Lucca, in collaboration with Professor Richard F. Hurrell, ETH Zürich and Hoffmann LaRoche, Basel).

Vitamin A-deficiency is often the consequence of rice being the predominant food in the diet. Rice endosperm does not contain any provitamin A. The latest precursor to the pathway in endosperm is GGPP. Four transgenes offer the potential to complete the pathway towards beta-carotene. These are phytoene synthase, phytoene desaturase, x-carotene desaturase and lycopene cyclase (all from Narcissus), or a double-desaturase from Erwinia catalysing both desaturation steps. The research team has generated a large series of transgenic plants which produce grain with yellow-colored endosperm. Biochemical analysis confirmed that the color represents beta-carotene (provitamin A) and other terpenoids of dietary interest. Some lines produce provitamin-A in high enough concentrations to supply the daily requirement with 300 grams of cooked rice. Genetic and molecular data demonstrate the transgenic nature of the phenotype. (Xudong Ye, Peter Burkhardt, Andreas Kloti, in collaboration with Peter Beyer and Salim Al-Babili, Freiburg).

This article comes from Science Blog. Copyright 2004