Genetically modified

Genetically modified crops

1. GENETICALLY MODIFIED CROPS DILSHANA FATHIMA M.Sc. BIOCHEMISTRY

2. INTRODUCTION Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material is modified in a way that does not occur naturally by mating or natural recombinations . The technology is often called modern biotechnology/ gene technology/ rDNA technology/ genetic engineering. Foods produced from/ using GMOs are often referred to usGM foods. GM crops are plants used in agriculture, the DNA of which has been modified using genetic engineering methods.

3. GM crops offer Improved yields Enhanced nutritional value Longer shelf life Resistance to drought, frost/insect pest One of the objective for developing plants based on GMOs is to improve crop protection. Resistance against insects is achieved by incorporating into the plant, gene for toxin production from the bacterium Bacillus thuringiensis GM crops that inherently produce this toxin have been reported to require lower quantities of insecticides in specific situations.

4. SAFETY The safety assessment of GM foods include Direct health effects (toxicity) Potential to provoke allergic reactions Stability of inserted gene Specific components having toxic properties Nutritional effects associated with genetic modification.

5. ECOLOGICAL CONCERNS If GM crops cross breed with wild relatives, the foreign transgenes could contaminate the natural ecosystem. Such genetic contamination can pose problems for certified producers. Some ecologists have warned about the harmful effects of BT corn on non target insects such as monarch butterflies that feed on wild milkweed growing near corn fields.

6. DIFFERENT GM CROPS BT Cotton Insect resistant transgenic crop Designed to combat the ballworm First GM crop of India BT produces Bt toxin that are insecticidal to the larvae of moths, butterflies, beettles , cotton ballworms etc. Bt cotton is created by the addition of genes encoding toxin crystals in the cry group of endotoxin . When insect eats cotton plant, the cry toxins are dissolved due to high pH in the stomach.

7. Dissolved & activated cry molecule bind to cadhesin like protein on cells comprising brush border molecule. Dissolves gut lining & leads to death of organism. BT Brinjal Created by inserting a crystal protein gene (cry1Ac) from the soil bacterium Bacillus thuringiensis into the genome of various brinjal cultivars. Developed to give resistance against lepidopteran insects, in particular, the brinjal fruit & shoot borer. Flavr savr tomato 1 st genitically engineered crop granted liscence for human consumption produced by californian company calgene (1992).

8. Calgene introduced a gene in plant which synthesize a complementary mRNA to polygalacturonase gene & inhibiting the synthesize of ph enzyme. Softening of fruits is largely due to degradation of cell wall by ph enzyme. 1 st genetically modified food was a tomato engineered to have longer shelf life (the flavr savr ) but never made it to market. Roundup ready alfalfa Resistant to glyphosate , the active ingredient in roundup. An RR alfalfa plot can be treated with roundup to control a broad range of weeds without harming the alfalfa crop.

9. This results in higher quality of alfalfa hay for livestock. Glyphosate is toxic to non GM alfalfa; infact it is used sometime to remove alfalfa fields when farmers wish to plant a different crop. The genetically modified variety of alfalfa has a single bacterial gene inserted into alfalfa DNA that codes for C 4 – EPSPS enzyme that can produce aminoacids necessary for plant growth & survival even in the presence of glyphosate . Corn (maize) Toxic to particular insects – European corn borers, corn car worms, corn rootworm larvae etc

10. The δ BT toxin attaches to the receptors in the gut, rupture the gut & kills the insect. Because Bt corn produces an insecticide within the tissues, the toxic proteins are protected from the sun & persist longer. Since Bt corn offers an alternative to spraying chemical insecticides, it offers environmental & economic benefits to farmers. Golden rice A variety of rice ( oryza sativa) produced through genetic engineering to biosynthesize β carotene, precursor of vitamin A in the edible parts of rice.

11. Golden rice differs from its parental strain by the addition of two β carotene biosynthesis gene. Psy ( phytoene synthesis) from daffodil Crt 1 from soil bacterium Erwinia uredovora It is a cheaper option to supply vitamin A required compared to other supplementary measure.

12. ADVANTAGES DISADVANTAGES Improved grain quality Protected yields Insect resistance Safer environment More nutritious food Reduce use of toxic pesticides Tolerance to high & low temperature, salt, drought etc Improves production & raise farmers income High risk to disruption of ecosystem & biodiversity Eventually disrupt the natural process of gene flow Its biologically altered, hence may pose a human health risk Excessive production of GM foods will be rendered ineffective overtime.

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