Table 1 Summary of key features of DNA-modifying technologies that have been employed for removal of selectable marker genes from plants
From: Less is more: strategies to remove marker genes from transgenic plants
System Name | Meganuclease | Site-specific recombinase | ZFN |
|---|---|---|---|
Enzyme involved | Homing nucleases | Site-specific recombinases | Zinc-finger fused Fokl nuclease |
System examples | l-Scel | Cre-lox, phiC31-att | Custom-designed ZFNs |
Recognition sites | Specific DNA sequence | Specific DNA sequence | Any endorgenous targeted DNA sequence |
Pre-inserted target sites | Needed [random insertion] | Needed [random insertion] | Not needed [locus specific] |
Reaction mode | Induce DSB and repair mechanism | Site-specific recombination | Induce DSB and repair mechanism |
Product | Not-conserved [through NHEJ repair] | Conserved | Not-conserved [through NHEJ repair] |
Concerns of using this technology | Natural existing sites in genomes | Pseudo sites in genomes | Low affinity of ZFN to target DNA |
Negative impacts from the concerns above | Genome fractionation | Chromosome rearrangement or deletion | Non-specific DSB induction at the non-specific sites |