The cold tolerance allele of teosinte enhances the chilling tolerance of modern maize

Maize originating from tropical areas is susceptible to low-temperature stress, lead to the loss of human food production. However, the molecular basis of the cold signaling transduction in maize remains unknown. This study identified a basic region/leucine zipper (bZIP) transcription factor (ZmbZIP68) as a negative regulator of maize chilling tolerance. We isolated mitogen-activated protein kinase (ZmMPK8) interact with and phosphorylate ZmbZIP68 at conserved Ser250 residue to enhance its stability. Genetic analysis demonstrated that ZmMPK8 negatively regulates maize chilling tolerance. Transcriptome analysis revealed the cold-induced expression of ZmDREB1s are repressed by ZmbZIP68. Furthermore, ZmMPK8-mediated phosphorylation enhances ZmbZIP68 binding affinity on ZmDREB1.7 promoter, thereby negatively regulating maize ZmDREB1.7 expression. Interestingly, ZmbZIP68 is located in a remarkably selecting region, indicating ZmbZIP68 may be a target of selection during early domestication. A indel-358 in ZmbZIP68 promoter has a significant effect on the activation of ZmbZIP68 that may cause chilling-tolerant diversity of maize and teosinte. Our study demonstrated the underlying mechanism for maize chilling adaption and provided a evolutionary cis-regulatory variant for maize cold-tolerant improvement.