Abstract

Temperature has a severe impact on maize height. However, the mechanisms by which maize regulates height in response to heat have not been fully established. Here, we perform a genome-wide association study and identify one single nucleotide polymorphism (SNP) located in the maize MIR172C promoter strongly associated with temperature-dependent plant height. This SNP is selected during maize domestication from tropical to temperate zones. Molecular evidence shows that the G-to-A variation enhances the binding of PIF4 to the MIR172C , greatly represses MIR172C transcription. Phenotyping indicates that MIR172C is highly expressed in the meristem to promote internode elongation. miR172c represses its target IDS1 and activates the brassinosteroid (BR) pathway in a temperature-dependent manner. Under heat stress, miR172s regulate IDS1 predominantly by translational inhibition. This study identifies a natural variation modulating temperature-dependent maize height and elucidates the underlying mechanism. This finding reports a key locus for future breeding to enhance environmental adaptability in maize.