Future Perspective on CRISPR-Cas9-Based Targeted Genome Editing in Date Palms

Date palm tree (Phoenix dactylifera L.) has been flourishing for millions of years and includes more than 600 varieties; moreover, date fruits are relished worldwide, especially in middle-eastern countries. Besides its popularity, the tree has undergone the least development through conventional breeding techniques compared with other crops because of its dioecious nature, wide heterozygosity, and long life cycle. Furthermore, conventional breeding approaches are laborious and time-consuming. Recently, biotechnology has emerged as a new dimension of science that has tackled the fundamental problems associated with date palms. Using this platform, multiple healthy plants can be generated within a short time through techniques of plant tissue culture. Moreover, the incorporation of desirable agronomic qualities, for instance, nutritional improvement, disease resistance, and increased yield, is feasible using various genome-modification technologies. For instance, zinc finger nucleases (ZNFs), transcription activator-like effector nucleases (TALENs), and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system. A precise approach known to be used to edit a particular segment in the genome with much greater accuracy, versatility, and competence compared with other techniques is CRISPR/Cas9. Extensive research was performed on date palms over the past decade, including genomic studies that have identified various genes responsible for different traits. Moreover, the elucidation of the genome sequences of several varieties represented a step toward gene editing technologies. This chapter provides a schematic layout of the implementation of CRISPR/Cas9-driven genome alteration of date palms as a sustainable strategy for crop improvement. The strategies involved in the production of transgene-free date palms and their applications, as well as the limitations of genome editing via CRISPR/Cas9 in these palms, are described in this chapter.