CRISPR-Cas9 based plant genome editing: Significance, opportunities and recent advances

Precise genome editing is a quantum leap in the field of plant sciences. Clustered regularly interspaced short palindromic repeats (CRISPR) and its associated Cas9 protein have emerged as a powerful tool for precise genome editing. CRISPR-Cas9 system introduces small heritable mutations (indels) in the genome of an organism. This system also enables precise gene characterization in plants with complex genomes. Besides, it offers new opportunities of trait stacking, where addition of desirable traits or removal of undesirable traits can be achieved simultaneously in a single event. With CRISPR-Cas9 RNPs technology, raising transgene free genetically modified plants is within realm of possibility which would be helpful in addressing regulatory concerns of transgenic plants. Several new advancements have been made in this technology which has extended its applications in almost every aspect of plant science. For example, recently developed catalytically inactive dCas9 fused with transcriptional effector domains allows targeted activation or silencing of the gene of interest. Apart from this, dCas9 fused with fluorescent labels is a budding tool in chromatin imaging studies. In this review, we summarize these recent advancements in CRISPR/Cas system and methods for analyzing the induced mutations, and its implementations in crop improvement.