Table 2.

Comparison of the strategies used in engineering antiviral plants

Strategies	Advantages	Disadvantages	Applications
RNA silencing	High efficiency and have several successful commercialized transgenic antiviral crops	Many viruses can encode VSRs to counter the defense of RNA silencing	Engineering resistance for the viruses without strong VSR, better effect on RNA viruses than DNA viruses
CRISPR/Cas targeting DNA	The eukaryotic plant viruses have not evolved to possess the ability to counter this immune defense coming from prokaryote	The targeted DNA viruses might be repaired and escape the engineered resistance. Off‐target effect may produce some heritable mutations in the host genome	Suites for the viruses having dsDNA genome or dsDNA replication intermediate. A virus‐induced promoter could reduce the off‐target effect
CRISPR/Cas targeting RNA	The targeted RNA is further degraded and has less chance to produce mutant viruses	Off‐target effect may affect the expression of some host genes, but will not change the plant genome	Engineering resistance to RNA viruses and DNA viruses with RNA intermediates
Host factors editing	The gene editing machinery can be removed by backcross, so it is able to engineer virus‐resistant plant which is transgenic‐free	Loss‐of‐function of some host factors may lead to lethality or impaired growth	Need to find a well‐characterized host factor and mutation of the factor will not affect the growth and reproduction of the plants