Virus-Free Improved Food in the Era of Bacterial Immunity

Prokaryotic cells defend themselves against bacteriophages and invasive plasmids deploying CRISPR-Cas machinery. The principles of CRISPR-Cas system have been briefly outlined here. One of the finest discoveries in the field of biotechnology is the demonstration that the CRISPR-Cas system, albeit in a modified form, also works well in the eukaryotic cells. The effector factors like Cas9 and Cas13 along with the guide RNAs have been engineered in plant cells to interfere directly with DNA and RNA viruses, respectively, thereby generating effective plant defense against the viruses. A few examples of such defense have been summarized in this chapter. A thermodynamic treatment of site-selectivity of Cas9-mediated DNA cleavage has been developed. Though the CRISPR-Cas system provides a robust weapon in the armory of anti-virus strategy, a few limitations of the system overshadow the advantages of the CRISPR-Cas system. These limitations have been discussed in the perspective section and need to be overcome for commercial exploitation of the virus tolerant plants.