Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are prearranged sections in bacterial as well as archaeal genomes, which form part of an adaptive immune system against phages —viruses that infect bacteria but not humans. CRISPR and CRISPR-associated (Cas) systems have been rapidly emerging as an alternative genomic editing tool to ZFNs (zinc-fingernuclease) and TALENs (Transcription activator-like effector nucleases).
In the article, “Targeted mutagenesis in rice using CRISPR-Cas system,” the author applies CRISPR/Cas system in rice (Miao, et al.). The author investigates whether the CRISPR/Cas technology can create double standard breaks (DSB) in rice callus. The successful application of CRISPR/Cas system for the targeted mutagenesis in rice was presented in the study.
Their result indicates that for sgRNA, almost 83.3% and 91.6% for CAO1 and LAXY1, respectively, of the independent lines of the first transgenic rice beard mutation, where four lines for CAO1 (13.3 percent) and six lines for LAZY1 (50 percent), had biallelic mutations. These results show that mutated genes of interest and transgenic rice can easily be generated through transgenic generation with the help of CRISPR/Cas system. In addition, high effectiveness of a target mutagenesis, which is possible as a result of unique features of CRISPR/Cas system, can be achieved through various genes.
Overall, when integrated stably, the CRISPR/Cas system can generate detectable mutations at a frequency of 50-89% for one locus and 68-74% for double loci in plants. However, multiple editing with ZFNs or TALENs demands separate dimeric proteins assembled for every target site. Particularly, it has been noted that high mutation frequency observed in rice is apparently as a result of a unique feature of the CRISPR/Cas system to tolerate DNA methylation at cleavage sites.
Works Cited
Miao, Jin, et al. "Targeted mutagenesis in rice using CRISPR-Cas system." Cell research 23.10 (2013): 1233.
Wood, Andrew J., et al. "Targeted genome editing across species using ZFNs and TALENs." Science 333.6040 (2011): 307-307.
