CRISPR-Cpf1 is an alternative to CRISPR-Cas0, as it targets sequences that
are inaccessible to Cas9 due to different recognizable sequence requirement.
Both systems are usually used to produce mutations on a target site in the
genome to enable the disruption of the gene of interest. A more limitedly
used function of these systems is the homology-directed repair (HDR) of a
DNA sequence of interest. In HDR, a specific allele is replaced or
introduced to the genome.
In the study, scientist Lanqin Xia from the Chinese Academy of Agricultural
Sciences and colleagues, replaced the wild-type ALS gene with a mutated
version, which confers herbicide resistance, in rice using the CRISPR-Cpf1
system. They observed that using the left homologous arm as the only donor
repair template is enough for a precise targeted allele replacement. The
study allows a better understanding on and greatly simplified HDR in rice.