FIGURE 2.

Special cases of TGE. (A) Combining haploid induction and gene editing (HI-Edit) in maize. A WT elite maize inbred line is pollinated using a haploid inducer line that contains a CRISPR/Cas9 containing T-DNA locus (red triangle). After fertilization, the male genome is gradually eliminated, but the temporary presence of CRISPR/Cas9 may still edit the elite allele. After doubling of the haploid plant genome using colchicine, a homozygous edited elite DH0 line is obtained (Kelliher et al., 2019; Wang et al., 2019). (B) CRISPR/Cas9 gene editing in Arabidopsis thaliana using floral dip. The female gametophyte (T0) is transformed using Agrobacterium tumefaciens leading to a transformed egg cell that may already be edited. Self-pollination with WT pollen leads to a fertilized egg cell and subsequent zygote in which TGE may take place.