The GE-ZmCCT9 KO was created with CRISPR/ Cas9 technology to knockout the endogenous ZmCCT9 gene in maize inbred line ZC01. Two 20-bp sequences in the first and second exons of ZmCCT9 were selected as target sites for Cas9 cleavage. Knockout of ZmCCT9 causes early flowering under long days.

PCR and sequencing analysis of 20 independent first-generation (T0) transgenic lines identified three homozygous mutations with deletions in the target sites that truncated the ZmCCT9 ORF; these are referred to as KO#1, KO#2, and KO#3.

Source:

Huang et al., (2018). ZmCCT9 enhances maize adaptation to higher latitudes. Proc Natl Acad Sci 9,115(2):E334-E341.