Abstract
The present paper reviews the developments in the use of the CRISPR Cas 9 system for crop improvement and crop variety development. The CRISPR Cas 9 tool is a prominent and efficient technology in gene manipulation employed for crop improvement in horticultural and agricultural crops. These tools are more accurate than zinc finger Nucleases (ZFNs) and transcription activator, such as effecter nucleases (TALENs) in generic manipulation. Until the year 2020, this was employed for crop improvement program of 41 food crop species, 15 industry crops, 6 oil crops, 8 ornamental crops and 1 fibre crop. The tool is utilized for morphological characters, flowering and yield, biofortification and quality improvement charters, resistance to biotic and abiotic stress, self incompatibility management, male sterility, haploid induction, translation modification in crops, etc. The tool has been used in the development of several varieties such as waxy corn maize, New Kasalath rice, New TeTe Pu rice, and modified Swarna Rice fulfilling the desired traits. Further, the tool would overcome constraints of inbreeding depression, stress tolerance, embryo breakdown in the crops. Assessment of the available information shows that most of the reported work are related to improving the quality and disease resistance of crops (which are governed by mono or oligogenic genes) rather than growth and yield characters (governed by polygenic genes). This tool will be a very effective and useful method for crop improvement integrated with conventional methods leading to important developments in agriculture industry and the farming community.