Genetically modified food
Method
Genetic modification involves the insertion or deletion of genes. In the process of Cisgenesis genes are artificially transferred between organisms that could be conventionally bred. In the process of Transgenesis genes from a different species are inserted, which is a form of horizontal gene transfer. In nature this can occur when exogenous DNA penetrates the cell membrane for any reason. To do this artificially may require attaching the genes to a virus or just physically inserting the extra DNA into the nucleus of the intended host with a very small syringe, or with very small particles fired from a gene gun. However, other methods exploit natural forms of gene transfer, such as the ability of Agrobacterium to transfer genetic material to plants, and the ability of lentiviruses to transfer genes to animal cells.
Development
The first commercially grown genetically modified whole food crop was a tomato (called FlavrSavr), which was modified to ripen without softening, by a Californian company Calgene. Calgene took the initiative to obtain FDA approval for its release in 1994 without any special labeling, although legally no such approval was required. It was welcomed by consumers who purchased the fruit at a substantial premium over the price of regular tomatoes. However, production problems and competition from a conventionally bred, longer shelf-life variety prevented the product from becoming profitable. A variant of the Flavr Savr was used by Zeneca to produce tomato paste which was sold in Europe during the summer of 1996. The labeling and pricing were designed as a marketing experiment, which proved, at the time, that European consumers would accept genetically engineered foods.
Currently, there are a number of food species in which a genetically modified version exists.
Food
Properties of the genetically modified variety
Modification
Percent Modified in US
Percent Modified in world
Soybeans
Resistant to glyphosate or glufosinate herbicides
Herbicide resistant gene taken from bacteria inserted into soybean
89%
TBA
Corn, field
Resistant to glyphosate or glufosinate herbicides, Insect resistance - using Bt proteins some previously used as pesticides in organic crop production.
Vitamin-enriched corn derived from South African white corn variety M37W has bright orange kernels, with 169x increase in beta carotene, 6x the vitamin C and 2x folate. || New genes added/transferred into plant genome. || 60% || TBA
Cotton (cottonseed oil)
Pest-resistant cotton
Bt crystal protein gene added/transferred into plant genome
83%
62%
Hawaiian papaya
Variety is resistant to the papaya ringspot virus.
New gene added/transferred into plant genome
+50%
TBA
Tomatoes
Variety in which the production of the enzyme polygalacturonase (PG) is suppressed, retarding fruit softening after harvesting.
A reverse copy (an antisense gene) of the gene responsible for the production of PG enzyme added into plant genome
Taken off the market due to commercial failure.
None
Potatoes
Amflora variety produces waxy potato starch composed almost exclusively of the amylopectin component of starch.
The gene for granule bound starch synthase (GBSS) (the key enzyme for the synthesis of amylose) was switched off by inserting antisense copy of the GBSS gene.
Amflora will be produced solely under contract farming conditions and not made available on the general market.
TBA
Rapeseed (Canola)
Resistance to herbicides (glyphosate or glufosinate), high laurate canola
New genes added/transferred into plant genome
75%
TBA
Sugar cane
Resistance to certain pesticides, high-sucrose cane.
New genes added/transferred into plant genome
TBA
TBA
Sugar beet
Resistance to glyphosate, glufosinate herbicides
New genes added/transferred into plant genome
TBA
TBA
Sweet corn
Produces its own bioinsecticide (Bt toxin)
Gene from the bacterium Bacillus thuringiensis added to the plant.
TBA
TBA
Rice
Genetically modified to contain high amounts of Vitamin A (beta-carotene)
"Golden rice" Three new genes implanted: two from daffodils and the third from a bacterium
TBA
TBA
In addition, various genetically engineered micro-organisms are routinely used as sources of enzymes for the manufacture of a wide variety of processed foods. These include alpha-amylase from bacteria, which converts starch to simple sugars, chymosin from bacteria or fungi that clots milk protein for cheese making, and pectinesterase from fungi which improves fruit juice clarity.
Growing Genetically Modified crops
Between 1997 and 2005, the total surface area of land cultivated with GMOs had increased by a factor of 50, from 17,000 km2 (4.2 million acres) to 900,000 km2 (222 million acres).
Although most GM crops are grown in North America, in recent years there has been rapid growth in the area sown in developing countries. For instance in 2005 the largest increase in crop area planted to GM crops (soybeans) was in Brazil (94,000 km2 in 2005 versus 50,000 km2 in 2004.) There has also been rapid and continuing expansion of GM cotton varieties in India since 2002. (Cotton is a major source of vegetable cooking oil and animal feed.) It is predicted that in 2008/9 32,000 km2 of GM cotton will be harvested in India (up more than 100 percent from the previous season).
Indian national average cotton yields of GM cotton were seven times lower in 2002, because the parental cotton plant used in the genetic engineered variant was not well suited to the climate of India and failed. The publicity given to transgenic trait Bt insect resistance has encouraged the adoption of better performing hybrid cotton varieties, and the Bt trait has substantially reduced losses to insect predation. Though controversial and often disputed, economic and environmental benefits of GM cotton in India to the individual farmer have been documented.
In 2003, countries that grew 99% of the global transgenic crops were the United States (63%), Argentina (21%), Canada (6%), Brazil (4%), China (4%), and South Africa (1%). The Grocery Manufacturers of America estimate that 75% of all processed foods in the U.S. contain a GM ingredient . In particular, Bt corn, which produces the pesticide within the plant itself, is widely grown, as are soybeans genetically designed to tolerate glyphosate herbicides. These constitute "input-traits" are aimed to financially benefit the producers, have indirect environmental benefits and marginal cost benefits to consumers.
In the US, by 2006 89% of the planted area of soybeans, 83% of cotton, and 61% corn were genetically modified varieties. Genetically modified soybeans carried herbicide-tolerant traits only, but maize and cotton carried both herbicide tolerance and insect protection traits (the latter largely the Bacillus thuringiensis Bt insecticidal protein). In the period 2002 to 2006, there were significant increases in the area planted to Bt protected cotton and maize, and herbicide tolerant maize also increased in sown area.
Crop yields
Some scientific studies have claimed that genetically modified varieties of plants do not produce higher crop yields than normal plants. However, other scientific studies dispute these claims.[citation needed]
One study by Charles Benbrook, Chief Scientist of the Organic Center, found that genetically engineered Roundup Ready soybeans do not increase yields (Bendrook, 1999). The report reviewed over 8,200 university trials in 1998 and found that Roundup Ready soybeans yielded 7-10% less than similar natural varieties. In addition, the same study found that farmers used 5-10 times more herbicide (Roundup) on Roundup Ready soybeans than on conventional ones.
Coexistence and traceability
The United States and Canada do not require labeling of genetically modified foods. However in certain other regions, such as the European Union, Japan, Malaysia and Australia, governments have required labeling so consumers can exercise choice between foods that have genetically modified, conventional or organic origins. This requires a labeling system as well as the reliable separation of GM and non-GM organisms at production level and throughout the whole processing chain. Research suggests that this may prove impossible.[citation needed]
For traceability, the OECD has introduced a "unique identifier" which is given to any GMO when it is approved. This unique identifier must be forwarded at every stage of processing.[citation needed] Many countries have established labeling regulations and guidelines on coexistence and traceability. Research projects such as Co-Extra, SIGMEA and Transcontainer are aimed at investigating improved methods for ensuring coexistence and providing stakeholders the tools required for the implementation of coexistence and traceability.[citation needed]
Detection
Testing on GMOs in food and feed is routinely done using molecular techniques like DNA microarrays or qPCR. These tests can be based on screening genetic elements (like p35S, tNos, pat, or bar) or event-specific markers for the official GMOs (like Mon810, Bt11, or GT73). The array-based method combines multiplex PCR and array technology to screen samples for different potential GMOs , combining different approaches (screening elements, plant-specific markers, and event-specific markers).
The qPCR is used to detect specific GMO events by usage of specific primers for screening elements or event-specific markers. Controls are necessary to avoid false positive or false negative results. For example, a test for CaMV is used to