Popular Article Polymerase Chain Reaction: A Robust Technology for Crop Improvement Vivekanand Tiwari*, Kiran Patel, Viral B. Mandaliya, and Sujit Kumar Bishi Directorate of Groundnut Research, PB-05, Ivnagar Road, Junagadh-362 001, Gujarat *Email of corresponding author: vivekcas805@gmail.com Introduction In 1983, Karry Mullis and co-workers have developed PCR technique to replicate fragments of DNA by semi-conservative method but under in-vitro condition. The introduction of thermostable Taq DNA polymerase from Thermus aquaticus has facilitated automation of this technology (Saiki et al., 1988). The technique was patented by Kary Mullis at Cetus Corporation, where he invented. The use of this invention for crop improvement was widely accepted in the areas of research like detection of plant pathogens, development of genetic or physical map of crop genome, cloning and characterization of existing or new trait responsive genes and their expression pattern analysis, genetic diversity analysis and marker assisted breeding for development of new crop varieties. Although, PCR has become a routine tool in molecular biology research for crop improvement studies, but still there are few important points should be taken care while performing a PCR. Different modifications in the components and reaction conditions have been adopted according to the applications or aim of the experiments for successful PCR reaction. This articles focus on the basic principle of PCR, what are the precautions should be taken care and application of PCR for crop improvements. Principle of PCR The principle of a PCR reaction can be generalized as the, in-vitro replication of small fragment of template DNA upto a desired size (< 10 kb). The DNA product formed after PCR are known as amplicons. Amplicons are increased in number exponentially after completion of each cycle. It includes separation of two opposite DNA strand by heat denaturation instead of enzymatic unwinding occurs in cells. A pair of small single stranded DNA fragments Popular Kheti Volume -2, Issue-3 (July-September), 2014 Available online at www.popularkheti.info © 2014 popularkheti.info ISSN: 2321-0001 Polymerase Chain Reaction (PCR) is widely used molecular biology research tools discovered by Kary Mullis in 1983. In this technology, with use of thermostable Taq DNA polymerase a fragment of DNA was transcribed in-vitro. The amplification was carried out using small fragment of DNA complementary to both ends of the DNA to be amplified and called as primer. Primers were designed carefully to avoid non-specific amplification. This technology widely used in crop improvement programs like development of genetic or physical map of crop genome, cloning and characterization of existing or new trait responsive genes and their expression pattern analysis, genetic diversity analysis and marker assisted breeding for development of new crop varieties. Popular Kheti ISSN: 2321-0001 225