A copy number variation in the ZmMADS1 promoter enhances maize adaptation to high altitudes

A 178-bp copy number variation in the ZmMADS1 promoter represses ZmMADS1 expression and results in delayed flowering, which has been a target of selection during maize spread into higher altitudes. ZmMADS1 promotes maize flowering via the autonomous pathway by directly activating the expression of ZmMADS69 and ZCN8, while repressing ZmRap2.7.