The fundamental techniques of plant science have been applied throughout human history. When early man went through the crucial transition from nomadic hunter to settled farmer, cultivated crops became vital for survival. These primitive farmers, although ignorant of the natural principles at work, found that they could improve each succeeding year's harvest by using seed from only the best plants of the current crop. Plants that, for example, gave the highest yield, stayed the healthiest during periods of drought or disease, or were easiest to harvest tended to produce future generations with these same characteristics. Through several years of careful seed selection, farmers could maintain and strengthen such desirable traits

The possibilities for improving plants expanded as a result of Gregor Mendel’s  investigations in the mid-1860s of hereditary traits in peas. Once the genetic basis of heredity was understood, the benefits of cross-breeding, or hybridization, became apparent. Today using the techniques of hybridization, recombinant DNA, genetic engineering and tissue culture genetically modified plants with different desirable traits can be produced.

Genetically modified crops can elevate the world of hunger and can provide food not only for the hundreds of millions of people already malnourished but also for the billions of additional people to come. One of the obvious application of GM agriculture is increase in crop yield, other desirable characters are: 

• Reduced vulnerability of crops to environmental stresses – introduction of At-DBF2 gene from Arabidopsis thaliana to provide salt, drought, cold and heat resistance to plants.
• Increased nutritional qualities - Proteins in foods, essential amino acids   and vitamins (golden rice).
• Improved taste, texture, appearance and shelf life of food.
• Reduced dependence on fertilizers, pesticides and other agrochemicals –  introduction of genes like Bt toxin for insect resistance, herbicide  resistance etc.
• Pharmaceuticals: Edible vaccine etc. in tomato or potato.
• Phytoremediation: land reclamation and cleaning up ground water.

The GM foods come with their fair share of controversies. The scientists and the general public are all concerned about the environmental, health risks and the economic issues. The agribusiness and Governments are being criticized for pushing these products without conducting adequate impact studies.