The miR164e-NAC32 module orchestrates maize plant height by post-translational regulation of DELLA protein stability

Plant architecture optimization requires precise regulation of internode elongation, yet the post-translational mechanisms integrating microRNA and phytohormone signaling remain poorly understood. Here, we decipher a hierarchical miR164e-NAC32-DELLA regulatory network controlling maize stem development. Genetic analyses demonstrate that ZmmiR164e negatively modulates target gene ZmNAC32, with its overexpression enhancing internode cell elongation and its loss-of-function resulting in dwarfism. Crucially, ZmNAC32 physically interacts with DELLA protein ZmD8 to stabilize its accumulation, as evidenced by increased ZmD8 protein levels in ZmNAC32-overexpressing lines compared to wild type. Transcriptome profiling reveals that ZmNAC32-mediated height regulation operates through post-translational stabilization rather than transcriptional reprogramming, with downstream cell wall biosynthesis genes (EXP, XTH, LAC) showing GA-responsive suppression. Structural analyses reveal that ZmNAC32 binding stabilizes ZmD8 by shielding the key interaction residue K399, thereby suppressing its degradation. All results reveal a miRNA-NAC-DELLA module governing post-translational protein stability in stem development, providing strategic targets for precision breeding of plant architecture.