Resource information
Transgenic plants are produced via Agrobacterium mediated transformation and other direct DNA transfer methods. A number of transgenes conferring resistance to insects, diseases and herbicide tolerance have been transferred into crop plants from a wide range of plant and bacterial systems. In the majority of the cases, the genes showing expression in transgenic plants are stably inherited into the progeny without detrimental effects on the recipient plant. More interestingly, transgenic plants under field conditions have also maintained increased levels of insect resistance. Now, transgenic crops occupy 44.2 million hectares on global basis. During the last 15 years, transformations have been produced in more than 100 plant species; notable examples include maize, wheat, soybean, tomato, potato, cotton, rice, etc. Amongst these herbicide tolerant and insect tolerant cotton, maize and soybean carrying Bacillus thuringiensis (Bt) genes are grown on a commercial scale. Genetic transformation and gene transfer are routine in many laboratories. However, isolation of useful genes and their expression to the desired level to control insect pests still involves considerable experimentation and resources. Developing pest resistant varieties by insertion of a few or single specific gene(s) is becoming an important component of breeding. Use of endotoxin genes such as Bt and plant derived genes (proteinase inhibitors) to the desired levels offers new opportunities to control insects and strategies involving combination of genes. Transgenic technology should be integrated in a total system approach for ecologically friendly and sustainable pest management. Issues related to Intellectual property rights, regulatory concerns, and public perceptions for release of transgenics need to be considered. Providing wealth of information on gene expression in higher plants by switching the gene on and off as and when required, makes gene manipulation a more direct process for genetic improvement of crops.
