Abstract
CRISPR/Cas systems confer immunity against invading nucleic acids and phages in bacteria and archaea. Recent studies have shown that CRISPR/Cas9 system is capable of targeting the genomes of DNA viruses and can interfere with viral activity and limit viral symptoms in planta, demonstrating the utility of this system for engineering molecular immunity in plants. CRISPR/Cas9 can efficiently target single and multiple viral infections and confer plant immunity. CRISPR/Cas13a (known previously as C2c2) is a class 2 type VI-A ribonuclease capable of targeting and cleaving single-stranded RNA (ssRNA) molecules of the phage genome. CRISPR/Cas13a has been shown to confer modest interference against RNA virus in plants. Here, I discuss the use of different CRISPR/Cas systems to engineer molecular immunity against DNA and RNA viruses in plants. I also highlight the potential challenges encountered when producing plants with engineered resistance to single and mixed viral infections.