CRISPR/Cas-mediated genome editing for crop improvement: current applications and future prospects

Conventional breeding techniques for crop improvement are based on hybridization and selection. However, due to the long breeding cycles of crops and the potentially unpredictable effects of traditional breeding, these techniques are not sufficient to meet market demands for crops with a variety of traits or to address the emerging food crisis we could face in the near future. In the past decade, advanced technologies such as next-generation sequencing have been used to rapidly produce massive amounts of genome sequence information in many crop species. These techniques, together with targeted genome editing tools such as Zinc Finger Nuclease (ZFNs) and Transcription Activator-Like Effector Nucleases (TALENs), Clustered Regularly Interspaced Short Palindromic Sequences (CRISPR)/CRISPR-associated protein (Cas) have increased the possibilities for crop improvement via targeted genome editing. The use of these technologies in crop biology has opened up a new era of genome editing-mediated crop breeding. In this review, we summarize the current techniques used for site-directed genome editing in plants, focusing on the CRISPR/Cas system, and discuss their current and future applications for crop biology.