Abstract

Flowering time and related trait anthesis–silking interval (ASI) are agronomic traits that impact the yield of maize ( Zea mays ). However, the precise molecular networks orchestrating maize flowering and the ASI remain poorly understood. ZEA CENTRORADIALIS 8 ( ZCN8 ), a florigen gene, plays a central role in floral transition. Here, using ZCN8 as a marker, we analyzed transcriptome data from diverse maize inbred lines and identified a basic helix–loop–helix transcription factor, ZmbHLH180. Overexpression of ZmbHLH180 markedly increased ZCN8 transcript abundance and accelerated overall flowering, as evidenced by earlier heading, silking, and anthesis. In contrast, Zmbhlh180 knockout mutants exhibited significantly delayed flowering but a shortened ASI. Transcriptional activation coupled with electrophoretic mobility shift assays demonstrated that ZmbHLH180 directly binds to the E-box motif in the ZCN8 promoter to activate its expression. Furthermore, haplotype-based association analysis revealed that natural variation in the ZmbHLH180 promoter significantly affects both flowering time and ASI. Together, these findings establish ZmbHLH180 as a key upstream regulator of ZCN8 and demonstrate that its natural variation is significantly associated with the coordination of flowering time and ASI