ZmCCT is a crucial gene for the nat

ZmCCT is a crucial gene for the natural spread of maize from tropical to temperate regions. Functional validations have indicated that, during evolution, the acquisition of a CACTA-like transposable element (TE) located ~2 kb upstream of ZmCCT represses its expression and attenuates photoperiod sensitivity, thereby accelerating maize spread to LD regions (Hung et al. 2012; Yang et al. 2013). Interestingly, ZmCCT is also responsible for maize resistance to Gibberella stalk rot, and the aforementioned TE insertion in ZmCCT compromises its resistance to this disease (Wang et al. 2017). A recent study revealed that ZmCCT is also closely associated with variation of tassel architecture, such as its length, branch length, and branch number (Xu et al. 2017). The presence or absence of TE insertions at the ZmCCT promoter region has led to the substantial divergence of ZmCCT promoter sequence. At least 15 ZmCCThaplotypes have been isolated, of which 9 have no TE insertion (non-TE), namely H3–H7 and H12–H15. Furthermore, H12–H15 are rare haplotypes which have a sample size