The CRISPR editing system requires an enzyme that recognizes a specific site called PAM and acts as the scissor to cut the DNA sequence of interest. Cas9 is the most frequently used enzyme for this system as it recognizes a guanine-rich PAM and cuts the DNA bluntly, allowing for the natural repairing mechanism of the cell to introduce a modification to the target DNA sequence. Cas12a or Cpf1 has been discovered and proven to perform better than Cas9, as it recognizes a thymine-rich PAM, cuts and produces sticky ends, and is applicable for multiple gene targeting.

Among several researchers, Pengcheng Wei of Anhui Academy of Agricultural Sciences in China and colleagues applied the Cpf1 system in rice. In their study, they applied the CRISPR-Cpf1 system to target OsPDS and OsGS3 genes in rice. Findings show approximately 78 and 92 percent mutating efficiency of the system in the two genes, respectively. The researchers further modified the system and included a different promoter to enhance the system. Results showed enhanced mutation efficiency of the system in rice. 

For more information, read the article in Plant Biotechnology Journal.