CRISPR applications in plant virology: virus resistance and beyond

CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated genes)is a prokaryotic adaptive immune system which has been reprogrammed into a precise, simple and efficient gene targeting technology. This emerging technology is revolutionizing various areas of life sciences, medicine, biotechnology and has raised significant interest among plant biologists, both in basic science and in plant protection and breeding. In this review, we describe the basic principles of CRISPR/Cas systems, and how they can be deployed to model plants and crops for the control, monitoring and study of the mechanistic aspects of plant virus infections. We discuss how Cas endonucleases can be used to engineer plant virus resistance by directly targeting viral DNA or RNA, as well as how they can inactivate host susceptibility genes. Additionally, other applications of CRISPR/Cas in plant virology such as virus diagnostics and imaging are reviewed. The review also provides a systemic comparison between CRISPR/Cas technology and RNA interference approaches, the latter of which has also been used for development of virus resistant plants. Finally, we outline challenges to be solved before CRISPR/Cas can produce virus-resistant crop plants which can be marketed.