Will the next generation of genetically modified crops improve public acceptance of biotechnology?
Critics of transgenic technology claim that genetically modified (GM) crops currently in commercial production only benefit producers and a few large agricultural corporations and offer nothing to the general public. While it can be argued that some changes in crop production associated with transgenics do benefit the consumer - reduced pesticide applications with Bt cotton, for example - it is true that the first GM crops to reach the market were not developed to provide direct benefits for consumers. New transgenics now in development, however, could change this dramatically, with crops being genetically modified for enhanced nutritional or other health benefits. Exciting current examples include golden rice, cavity-fighting apples, and antioxidant tomatoes, and edible vaccines in bananas.
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Rice plants |
Golden rice
Although rice is a staple in the diet
of much of the world population, the grain is low in several key
nutrients, including vitamin A. Golden rice has had two daffodil genes
inserted coding for the enzymes which produce beta carotene. This is then
converted to vitamin A in the human body. The presence of the beta
carotene turns the rice grain yellow, hence the popular name for this GM
crop. U.N.I.C.E.F. estimates that 124 million children around the world
suffer from vitamin A deficiency, resulting in half a million cases of
childhood blindness annually. Because the current version of golden rice
does not deliver the full daily requirement of vitamin A, consuming golden
rice will not solve this problem alone. However, it will make a
contribution to a better diet for many people if supplies are made
available at an affordable price. Golden rice arrived in the Philippines
in January 2001, where plant breeders at the International Rice Research
Center are now developing locally adapted strains for distribution to
farmers.
Cavity-fighting apples
Medical researchers at
Guy’s Hospital in London and scientists at the Horticultural Research
Institute in Kent, U.K., are developing apples with a bacterial gene
coding for a protein which prevents decay-causing bacteria from attaching
to teeth. Results to date suggest that eating the GM apples could
significantly reduce cavity formation.
Antioxidant tomatoes
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Tomatoes |
Flavonols are powerful antioxidants with the ability to neutralize harmful tissue-damaging molecules circulating in the body. Some foods, such as onions and tea, are naturally rich in flavonols, and several current research projects involving GM crops aim to increase beneficial antioxidant levels in other food plants. Scientists at Unilever have inserted a petunia gene into tomatoes which increases flavonol production up to 78 times over the relatively low levels normally found in the fruits. Taste is not affected, and 65% of the flavonols are retained when the tomatoes are processed into paste. Researchers have coined the term “functional foods” for items such as this, where conventional breeding or transgenic technology have enhanced levels of compounds in plant or animal products with health benefits beyond basic nutritional requirements.
Edible vaccines
Several crop species have been
genetically modified to produce plant-based vaccines, which can be
administered by consuming the plant product. One of most promising
plant-based vaccines confers resistance to the liver disease hepatitis B
through eating a dried GM banana chip. Researchers at the Boyce Thompson
Institute at Cornell University have also modified tomatoes with a key
gene from the hepatitis B virus, and found that small quantities of
processed or dried tomatoes produced antibodies against hepatitis B when
consumed. A dose of tomato- or banana-based hepatitis B vaccine costs
around 2 cents per dose, less than 1% of the cost of a conventional
hepatitis B vaccine.
Another frequent criticism of transgenic technology is that GM crops have not resulted in increased food production, especially in developing countries. New transgenics now in development could help solve the problem of feeding a world where the human population keeps expanding but usable agricultural land does not. Among examples recently in the news are salt-tolerant tomatoes and iron-pumping rice.
Salt-tolerant tomato
Researchers at the
University of California at Davis have produced a GM tomato which can grow
in soil irrigated by water containing up to 200 millimolar sodium
chloride, 50 times the salt content normally tolerated by unmodifed
tomatoes. The tomato contains a gene from thale cress (Arabidopsis
thaliana) which segregates sodium ions from intracellular water for
storage in vacuoles. Fruit from the salt-tolerant tomatoes tastes normal
-- the salt is stored in vacuoles in the leaves.
Iron-pumping rice
Iron-deficient alkaline soils
are common in many of the world’s arid regions. Cereals such as corn and
barley release an iron chelator known as deoxymugineic acid (DMA) when
grown in such soils. DMA binds the iron and transports it across the root
membrane, enhancing uptake by the plant. Rice normally produces very small
quantities of DMA, making it an ineffective scavenger of iron in alkaline
soils. Japanese researchers have transformed rice plants with two barley
genes coding for enzymes which synthesize DMA. The GM rice plants have
greatly enhanced DMA production and iron uptake, and yield up to four
times more than non-GM rice when grown in iron-poor soils.
Public concern about transgenic technology in the U.S. and international opposition to it abroad, especially in Europe, have impacted markets for GM crops grown in the U.S. The future of GM technology depends on consumer acceptance of its products. Will the potential benefits offered by the next generation of GM crops be sufficient to persuade a skeptical international public?
