Multiplexed Genome Editing in Cereals

Multiplex genome editing techniques are newly designed powerful and flexible biotechnological tools for precisely modifying multiple targets in a genome. These genome editing techniques have increased the possibility of making desired modifications to a target genome at various nucleotide levels. Multiplex genome editing tools based on the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system permit the simultaneous creation of mutations at different loci in multiple genes or a single gene at the same time. Multiplex CRISPR-based genome editing is advancing the basic and applied research in modern crop breeding because it was previously impossible to edit genomes so precisely using earlier genome editing techniques such as zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs). Many cereal crops, including rice, maize, wheat, cotton, and sorghum, have successfully undergone genome editing using the multiplex CRISPR/Cas9 system. The accessibility of complete genome information along with advancements in genome editing tools, opens new avenues for achieving desirable traits. This chapter describes the current advances made toward the application and development of multiplex genome editing tools through the use of CRISPR/Cas9-based genome editing methods to accelerate the development of high-yielding and stress-tolerant cereal crops. Moreover, the challenges and strengths, and significance of emerging multiplexed gene editing technology for rapid and highly precise crop-improvement programs are discussed.