DNA-free genome editing methods for targeted crop improvement

Evolution of the next-generation clustered, regularly interspaced, short palindromic repeat/Cas9 (CRISPR/Cas9) genome editing tools, ribonucleoprotein (RNA)-guided endonuclease (RGEN) RNPs, is paving the way for developing DNA-free genetically edited crop plants. In this review, I discuss the various methods of RGEN RNPs tool delivery into plant cells and their limitations to adopt this technology to numerous crop plants. Furthermore, focus is given on the importance of developing DNA-free genome edited crop plants, including perennial crop plants. The possible regulation on the DNA-free, next-generation genome-edited crop plants is also highlighted.