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How are GMO crops made?

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Quick answer

GMO crops are made by adding a chosen gene to a plant's DNA. Scientists isolate a gene for a useful trait, such as insect resistance, and deliver it into plant cells using a modified bacterium or a gene gun. Cells carrying the gene are grown into full plants, then tested and approved before farmers grow them.

GMO crops are made by inserting a specific gene, often from another organism, into a plant cell's DNA so the plant gains a new trait such as pest resistance. Scientists then grow a whole plant from that modified cell, test it extensively and breed the trait into high-yielding varieties.

Step by step

  1. Researchers identify a gene responsible for a desired trait, such as the insect-killing protein gene from the bacterium Bacillus thuringiensis.
  2. They copy the gene and attach a promoter that switches it on in plant cells, plus a marker gene for selection.
  3. The gene construct enters plant cells through Agrobacterium infection or by firing DNA-coated particles with a gene gun.
  4. Only cells that carry the new gene survive the selection step and are grown in tissue culture into whole plants.
  5. The plants undergo field trials and safety reviews, and approved lines are bred into local high-yielding varieties.

Key things to understand

  1. Scientists first identify a gene that produces a useful trait, such as a protein that kills particular insect pests.
  2. The gene is copied and joined to control sequences that tell plant cells when and where to switch it on.
  3. It is delivered into plant cells, usually by a modified soil bacterium called Agrobacterium or by a gene gun.
  4. Cells that have taken up the gene are selected and grown in tissue culture into complete new plants.
  5. The new plants are tested for the trait, food safety and environmental effects before regulators approve them.

Labelled diagram

  1. Useful gene

    A DNA sequence for a desired trait is identified and copied.

  2. Gene construct

    The gene is joined to a promoter and a selectable marker.

  3. Delivery

    Agrobacterium or a gene gun carries the construct into plant cells.

  4. Tissue culture

    Modified cells are selected and regenerated into complete plants.

  5. Testing and breeding

    Field trials and safety reviews precede breeding into farm varieties.

From useful gene to genetically modified crop

Real-world examples

  • Bt cotton, approved in India in 2002, carries a bacterial gene that makes a protein toxic to bollworm caterpillars.
  • Herbicide-tolerant soybeans grown widely in the Americas survive sprays that kill surrounding weeds.
  • Virus-resistant papaya was developed in Hawaii to save the crop from papaya ringspot virus.
  • Golden Rice was engineered to produce beta-carotene, which the body converts into vitamin A.

Common mistake

✗ Myth: Eating GM food can transfer the added genes into your own DNA.

✓ Fact: All food, GM or not, contains DNA that digestion breaks down into small fragments. There is no evidence that genes from GM crops become part of human cells; safety reviews focus on the new proteins and nutrition.

People also ask

How are genetically modified crops made step by step?
Scientists identify a gene for a useful trait, copy it and attach control sequences. They insert it into plant cells using Agrobacterium or a gene gun, select the cells that took up the gene and grow them into whole plants. These undergo field trials and safety reviews before approval and breeding.
What is bt cotton and how does it work?
Bt cotton contains a gene from the soil bacterium Bacillus thuringiensis that makes a Cry protein. When bollworm caterpillars eat the plant, the protein binds to receptors in their gut and kills them. It is harmless to humans because our gut lacks those receptors. It is the GM crop most widely grown in India.
Why are gmo crops made?
GM crops are made to add traits that conventional breeding cannot easily provide. Common goals include resistance to insect pests or viruses, tolerance of herbicides for easier weed control and improved nutrition, such as extra vitamin A. Some aim to reduce pesticide use or help crops cope with drought.
How does Agrobacterium put genes into plants?
In nature this bacterium transfers a segment of its own DNA into plant cells, causing tumours. Scientists remove the tumour genes and replace them with the desired gene, so the bacterium delivers useful DNA into the plant's chromosomes instead.
What is a gene gun?
A gene gun coats microscopic gold or tungsten particles with DNA and fires them at high speed into plant cells. A few particles enter the nucleus, and in some cells the DNA becomes part of the plant's chromosomes.
Is gene editing the same as genetic modification?
Not exactly. Classic genetic modification adds a gene, often from another species. Gene editing tools such as CRISPR make precise changes to the plant's own DNA, and many countries regulate small edits differently from transgenic crops.
How long does it take to develop a GM crop?
From discovering a useful gene to commercial release typically takes many years, often more than a decade, because of laboratory work, multiple field trials, breeding into local varieties and regulatory safety reviews.

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