Gene knockout (GO) is a genetic technique supplemented with biotechnological tool, in which an organism is engineered to carry gene that has been made inoperative. These genes are known as knockouts; used in assigning function to specific genes having unknown function. Gene knockout strategy, reverse genetic tools, used to determine the function of target genes by gene technology, mutagenesis & homologous recombination. Homologous recombination permits gene exchange in vivo. This approach is commonly used in Arabdopsis to nullify the gene function. The technology was primordially developed in yeast Saccharomyces cerevisae. In a study, a group of Melbourne based company & other Japanese Suntory Companies tried to develop world’s biggest blue rose in 2008 by RNAi technology, making a rose with blue pigment. In another study, knockout mouse was first reported through homologous recombination. Knock-out mouse are often used as weapons for studying gene products & their functions.
Climatic aberrations such as drought and flood are causing threat to food production. Development of stress tolerant varieties is essential for maximum food production. Stress tolerance is complex and multigenic phenomenon. Transcription factors (TFs) play an vital role in regulating stress response transcription factors induce the expression of stress response genes (SOS genes) which causes physiological changes in plants hence, engineering transcription factors in crops is an effective and efficient way to induce drought tolerance. Under abiotic stress conditions most of the miRNA gets differentially expressed miRNAs that positively induce the expression of transcription factors can be used as candidate genes for production of stress tolerant plants by transgenic technology.