CRISPR/Cas9-based genome editing to expedite the genetic improvement of palms: Challenges and prospects

The recent demonstration of precise and efficacious genome editing using CRISPR/Cas9 in Elaeis guineensis has opened new opportunities for readily altering functionally important loci with fine control and short turn-around time in diverse oil palm (OP) genotypes. The first off-target validated mutant triple genotypes at three loci associated with the control of oil quality were generated in the current elite MPOB genetic background. Here, the latest achievements and ongoing developments in OP genome editing are reviewed, and the key challenges and guiding principles for the experimental design and implementation of genome editing are outlined. Advanced variations of the CRISPR/Cas9 system involving base editing for the effective manipulation of quantitative agronomic traits are also contemplated. Oil palm (OP) is a highly specialized oil crop producing mesocarp oil packed with highly desirable attributes. However, continuous expansion of OP cultivation has resulted in significant global environmental challenges. Genetic improvement plays a central role in mitigating OP intensive production. The recent use of the CRISPR/Cas9 technology in the genome editing of OP represents a significant milestone in OP molecular breeding. The technology permits the rapid generation of considerable new genetic variability through precise editing of functionally important OP loci in a series of cell types, which can then be used to generate whole organisms. Whether the objective is to generate novel expression alleles, knockouts, promoter replacements, exon modifications, or specific indel mutations, CRISPR/Cas9 technology provides an efficient, straightforward, and targeted system for genome manipulation. Furthermore, the applications are virtually endless for the development of innovative biotech products. By strategically designing DNA repair templates, researchers can introduce predefined changes, which can include specific insertions or deletions.