Improvement of Crop’s Stress Tolerance by Gene Editing CRISPR/CAS9 System

Abstract

There is an urgent need to enhance agriculture productivity to feed the world’s ever-increasing population on the one hand and stresses reducing global agriculture productivity on the other hand. Hence there is only one way to boost global agriculture productivity through innovative breeding technology that can provide access to food security worldwide. Moreover, the availability of fully sequenced genome of various crops in combination with the advancement in genome editing technologies (GETs) has opened the doors to plant biologists to edit almost any desirable trait as well as provided a magic stick for the crop’s functional genomics. First-generation GETs such as zinc finger nucleases (ZFNs), site-specific nucleases (SSNs), meganucleases, and transcription activator-like effector nucleases (TALENs) enable plant biologists to target any gene of interest. However, most of these technologies are extravagant, tedious, and burdensome. With the emergence of second-generation GETs, clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) offers an efficiently targeted modification of almost all crops and accelerating the crop improvement programs. CRISPR involves designing, cloning, and/or gene-free editing methods. CRISPR/Cas9 system includes a Cas9 protein that makes double-strand cut and a small guide RNA molecule that directs Cas9 to a specific sequence of DNA to cleave. The native DNA repair machinery of the cell generally repairs the nick and facilitates gene editing. CRISPR/Cas9-mediated genome editing (CMGE) has revolutionized agriculture by offering a tool for trait improvement, gene regulation, development of virus resistance, and the generation of mutant libraries. This chapter reviews a brief introduction about CRISPR/Cas9, future perspectives of CRISPR in plant synthetic biology and domestication, advances in CRISPR delivery systems, and specificity of editing. Besides this, there is a short discussion over challenges and opportunities for plant breeding and its fate in agriculture. The chapter also covers an inventory of CRISPR-edited crops until dates for enhancing crop stress tolerance.