Most researches on plant genome editing use the CRISPR-Cas9 system (SpCas9) from Streptococcus pyogenes. The recognition of spCas9 depends on the specific PAM sequence NGG, which greatly limits the selection range of editing sites in the system. In order to solve this problem, researchers look for solutions from different directions.
From 2065438 to March 2006, researchers from Wang Kejian's research group of China Rice Research Institute obtained variants of Cas9 protein through site-directed mutation, and successfully edited adjacent sequences in rice genome, greatly expanding the selection range of gene editing sites (Hu et al., 20 16). However, compared with the original CRISPR-Cas9-VQR system, the editing efficiency of CRISPR-Cas9 system is still low, which limits its popularization and application in rice.
On June 20th,17, 12, Wang Kejian's team cooperated with Li Jiayang's team from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and published an article entitled "Improved Efficiency? Precise genome editing of rice CRISPR-Cas9-VQR "(Hu et al., 20 18) significantly improves the genome editing efficiency of rice CRISPR-Cas9 and CRISPR-Cas9-systems by optimizing the structure of sgRNA and driving the expression of CAS9 and variants with strong endogenous promoters in rice. Through experiments, the highest editing efficiency in rice can reach nearly 80%, and the highest improvement range can reach 8 times. At the same time, the system can connect multiple sgRNA in series through isozyme connection, and edit multiple loci at the same time (for the construction method, see the article published in Journal of Genetics and Genomics by Dr. Wang Chun and Wang Kejian's team 20 15; Wang et al, 20 15). In multi-site editing, the efficiency is improved more obviously, which can reach 15 times. Therefore, the revised CRISPR-Cas9-VQR system will become a powerful tool for editing the target site of Duonga.