GM crops are the crops whose genetic makeup is modified. Genetic modification is usually employed in crop plants to increase the economic yield either by directly increasing the production, or by increasing the plants resistance to herbicides, pests, antibiotics etc. Genetic modification of crop is not a new concept. For centuries, food crops have been changed through selective breeding. While genes can be transferred during selective breeding, the scope for exchanging genetic material is much wider while using genetic engineering. Genetic modification of crop plants thus involves improving the yield quantity and quality either by the introduction of a genome for desired trait into the plant genome or by modifying the inherent plant genes specifically selected for the expression of a trait.