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The below mentioned article will highlight the applications and achievements in transgenic plants production.
1. Insect and Disease Resistance:
Resistance to insects and diseases has been achieved in many field crops through the use of transgenes.
For example, in the famous BT-cotton, a transgenic or genetically modified variety of cotton, gene for the insect Helicoverpa resistance has been transferred from soil-borne bacterium Bacillus thuringiensis by Monsanto company of U.S.A.
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The BT-cotton is now widely grown in India also. In corn, gene for resistance to European corn borer has also been transferred from above bacterium. In tobacco, insect resistance has been achieved by transferring trypsin inhibitor gene from cow pea. Transgenic virus resistant genotypes have been developed in crops like tobacco, tomato, potato and cucumbers.
2. Cold Resistance:
Cold resistance has been achieved in some crop plants through transgenic breeding. In tomato and tobacco, anti-freezing gene has been transferred from fish (winter flounder). In tobacco, cold resistance has been achieved by transferring a gene from Arabidopsis thaliana.
3. Improvement in Quality:
Improvement in quality has been achieved in some crop plants through transgenic breeding. Some examples are given here. In alfalfa, protein quality has been improved by transferring ovalbumin gene from chicken. In potato, protein quality has been improved by transferring serum albumin gene from human. In tobacco, protein quality has been enhanced by transferring glutenin gene of wheat.
4. Induction of Male Sterility:
Male sterility is gaining increasing importance these days due to increasing demand of hybrid varieties in various crops. Transgenic breeding is an effective means of inducing male sterility in crop plants. In rapeseed, male sterility has been induced by transferring a gene from Bacillus amyloliquefaciens.
5. Herbicide Resistance:
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In almost all crop plants, weeds pose a serious problem. The manual elimination of weeds is a very expensive method. The cheapest and the most practical method of weed control in the mechanized agriculture is the use of herbicides. However, herbicides have adverse effects on many crop plants. Hence, there is need to develop herbicide resistant genotypes in various crop plants.
Biotechnology (tissue culture and genetic engineering) has helped in developing transgenic plants resistant to herbicides in many crop plants. Herbicide resistant transgenic plants have been developed in cotton, tobacco, wheat, maize, potato, tomato, soybean, flax, rapeseed, sugar beet, alfalfa, cabbage and other crops. In majority of cases, herbicide resistant genes have been transferred from microorganisms (Dale and Irwin, 1995).
There are only few examples of the use of transgenes in crop improvement. In other words, this is just beginning of the application of biotechnology in crop improvement. Transgenic breeding is expected to play a key role in the genetic improvement of crop plants in the years ahead.
The maximum transgenic plants have been released in oil seed rape (290), followed by potato (133), tobacco and tomato (72) each and maize (65). Other crops in descending order include flax (49), soybean (40), cotton, (37), sugar beet (28), lucerne (21), etc.
