Introduction:
Bacillus thuringiensis or Bt is a naturally occurring soil bacterium
mostly used by farmers to control Lepidopteran insects because of its
toxin producing ability. Scientists have introduced the gene responsible
for making the toxin into a range of crops, including cotton. Bt
expresses the qualities of the insecticidal gene throughout the growing
cycle of the plant. Cotton and other monocultured crops require an
intensive use of pesticides as various types of pests attack these crops
causing extensive damage. Over the past 40 years, many pests have
developed resistance to pesticides.
Cotton crops are very susceptible to pest attacks and use up more
than 10 per cent of the world's pesticides and over 25 per cent of
insecticides. As of now, cotton is the most popular of the Bt crops. The
Bt gene was isolated and transferred from a bacterium bacillus
thurigiensis to American cotton. The American cotton was subsequently
crossed with Indian cotton to introduce the gene into native varieties.
So far, the only successful approach to engineering crops for insect
tolerance has been the addition of Bt toxin, a family of toxins
originally derived from soil bacteria. The Bt toxin contained by the Bt
crops is no different from other chemical pesticides, but causes much
less damage to the environment.
Benefits:
Bt cotton is in many ways an ideal candidate for introduction as a
transgenic commercial crop. It is basically grown as a fibre crop, while
cotton seed oil used for consumption is free of proteins, including Bt
protein. Environmental safety concerns are negligible because of the
limited movement of heavy cotton pollen and the existence of natural
genetic barriers that preclude out crossing with native Indian cotton.
There is also no known compatibility of cultivated cotton with any wild
relatives occurring in India. Cotton is not found as a weed in the
global production systems and Bt is unlikely to confer any advantage
that would result in Bt cotton establishing as a weed.
Read more on Impacts on: http://seedbuzz.com/knowledge-center/article/impact-of-bt-cotton-seeds-on-indian-agriculture
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