An Era of CRISPR/Cas9-mediated Plant Genome Editing

Recently the engineered nucleases have revolutionized genome editing to perturb gene expression at specific sites in complex eukaryotic genomes. Three important classes of these genome editing tools are Zinc Finger Nucleases (ZFN), Meganucleases and Transcription Activator-Like Effector Nucleases (TALEN) which work as hybrid systems comprising of target-specific DNA binding domains and molecular scissors or restriction endonucleases. Moreover, the more recent type II clustered regularly inter-spaced short palindromic repeats (CRISPR)-associated protein (CRISPR/Cas9) system has become the favourite plant genome editing tool for its precision and RNA based specificity unlike its counterparts which rely on protein based specificity. Plasmid-mediated co-delivery of multiple sgRNAs and Cas9 to the plant cell can simultaneously alter more than one target loci which enables multiplex genome editing. In this review, we discuss recent advancements in the CRISPR/Cas9 technology mechanism, theory and its applications in plants and agriculture. We also suggest that the CRISPR/Cas9 as an effective genome editing tool, has vast potential for crop improvement and studying gene regulation mechanisms and chromatin remodelling.