CRISPR-Based Directed Evolution for Crop Improvement.

Directed evolution involves generating diverse sequence variants of a gene of interest to produce a desirable trait under selective pressure. CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9) systems can be programmed to target any genomic locus and perform targeted directed evolution. Here, we discuss the opportunities and challenges of this emerging platform for targeted crop improvement.