Question

Write a short note on G.M crops?

Answer 1

Hint: Genetically modified organisms are those whose genes have been altered by manipulation called transgenic organisms.

Complete answer: The use of genetically modified plants has been useful in the following ways -
1. Genetic modification has made the crops more tolerant to abiotic stresses like cold, heat, drought, salinity, etc.
2. It has reduced the dependence of crops on chemical pesticides as they are made pest-resistant. Post-harvest losses are much reduced.
3. As the pants have increased the efficiency of mineral usage by plants, the early exhaustion of fertility of the soil is prevented.
4. Food produced from GM ( Genetically Modified ) crops have enhanced nutritional value.
Genetic modification has been used to create tailor-made plants to supply resources to industries such as starch, fuels, pharamceuticals, etc.

Additional information: In Bt cotton Bt toxin has been used as a biological insecticide. The Bacillus thuringiensis is a common soil bacterium that produces a protein toxin that kills certain insects. The toxin is a crystal cry protein.
1. Cry proteins are toxic to larvae of insects like lepidopteran, bollworm, beetles, etc.
2. The cry proteins exist as inactive protoxins and get converted into active toxin when ingested the insect as the alkaline pH of the gut solubilize the crystals.
3. The activated toxin binds to the surface of epithelial cells of the midgut and creates pores.
This causes swelling and lysis of cells leading to the death of insects (larva). The gene encoding the Cry protein is called the Cry gene.
4. The genes (cry genes ) encoding this protein are isolated from the bacterium and incorporated into several crop plants like cotton. The proteins encoded by the cry gene Cry I Ac and Cry II Ab control cotton bollworms.

Note: The other examples include transgenic tobacco plant, tomato plant, potato plant. The resistant gene reduces the crop yield loss due to attack by insects as result there is minimal use of insecticides.