Crispr Cas System in Plant Genome Editing a New Opportunity in Agriculture to Boost Crop Yield

Abstract

Clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) technology evolved from a type II bacterial immune system developed in 2013. This system employs RNA-guided nuclease, CRISPR-associated (Cas9), to induce double-strand breaks. The Cas9-mediated breaks are repaired by cellular DNA repair mechanisms and mediate gene/genome modifications. The system has the ability to detect specific sequences of letters within the genetic code and to cut DNA at a specific point. Simultaneously with other sequence-specific nucleases, CRISPR/Cas9 has already breached boundaries and made genetic engineering much more versatile, efficient, and easy. It has also been reported to increase rice grain yield by up to 25-30% and improve tomato fruit size, branching architecture, and overall plant shape. CRISPR/Cas has also mediated virus resistance in many agricultural crops. In this article, we reviewed the history of the CRISPR/Cas9 system invention and its genome-editing mechanism. We also described the most recent innovations in CRISPR/Cas9 technology, particularly the broad applications of modified Cas9 variants, and discussed the potential of this system for targeted genome editing and modification for crop improvement.

Abbreviations: CRISPR, clustered regularly interspaced short palindromic repeats; Cas, CRISPR-associated; crRNA, CRISPR RNA; tracrRNA, trans-activating crRNA; PAM, protospacer adjacent motif; sgRNA, single guide RNA; gRNA, guide RNA; ssODN, single-stranded DNA oligonucleotide; DSB, double-strand break; NHEJ, non-homologous end joining; HDR, homology-directed repair; CRISPRi, CRISPR interference.