dlf1promotes floral transition by directly activatingZmMADS4andZmMADS67in the maize shoot apex

The floral transition of the maize (Zea maysssp.mays) shoot apical meristem determines leaf number and flowering time, which are key traits influencing local adaptation and yield potential.dlf1(delayed flowering1) encodes a basic leucine zipper protein that interacts with the florigen ZCN8 to mediate floral induction in the shoot apex. However, the mechanism of howdlf1promotes floral transition remains largely unknown. We demonstrate thatdlf1underliesqLB7-1, a quantitative trait locus controlling leaf number and flowering time that was identified in a BC(2)S(3)population derived from a cross between maize and its wild ancestor, teosinte (Zea maysssp.parviglumis). Transcriptome sequencing and chromatin immunoprecipitation sequencing demonstrated that DLF1 binds the core promoter of twoAP1/FULsubfamily MADS-box genes,ZmMADS4andZmMADS67, to activate their expression. Knocking outZmMADS4andZmMADS67both increased leaf number and delayed flowering, indicating that they promote the floral transition. Nucleotide diversity analysis revealed thatdlf1andZmMADS67were targeted by selection, suggesting that they may have played important roles in maize flowering time adaptation. We show thatdlf1promotes maize floral transition by directly activatingZmMADS4andZmMADS67in the shoot apex, providing novel insights into the mechanism of maize floral transition.