Table 1 The pros and cons of different genome editing technologies in C. elegans

Functional enzyme

Cre recombinase and FLP flippase

Mos1 transposase

Customized fokI

Customized fokI

Cas9

Recognition

Protein-DNA

Protein-DNA

Protein-DNA

Protein-DNA

RNA-DNA

Mechanism of action

DNA recombination

Mos1 transposon elimination

Induce DSBs

Induce DSBs

Induce DSBs

Sequence limit

LoxP or FRT sequence

Mos1 transposon

No

No

PAM motif

Genetic background

Strain with extrachromosomal array

Mos1 insertion strain

Any

Any

Any

Specificity design

Targeted sequence flanked by LoxP or FRT sites

Targeted modifications within repair templates

Zinc finger modules, each binds to a particular nucleotide triplet

TALE modules with each binds to a single nucleotide

The first 20-nt of the sgRNA

Application

Conditionally regulate gene expression, remove co-integrated selection markers

Precise sequence alterations

Gene KO

Gene KO, conditional gene KO and precise sequence alterations

Gene KO, conditional gene KO, precise sequence alterations and chromosomal engineering