Antagonistic Regulation of the Conifer Age Marker DAL1 by GA and JA Via a TIFY25‐DPL1 Module

ABSTRACT

Conifers, as long‐lived gymnosperms, employ age‐regulatory mechanisms distinct from the miR156‐miR172 module dominant in angiosperms. The MADS‐box gene DAL1 serves as a conserved age marker in conifers, yet the hormonal modulation of its activity remains elusive. Here, we reveal that gibberellin (GA) and jasmonic acid (JA) exert antagonistic control over DAL1 protein abundance through mechanistically distinct pathways in Pinus tabuliformis . GA promotes DAL1 accumulation via the conserved GA‐GID1‐DELLA cascade. Conversely, JA suppresses DAL1 primarily through the transcription factor MYC2, which directly interacts with DAL1 to mediate its degradation. Strikingly, we uncovered a compensatory mechanism wherein JA‐induced TIFY25, a JAZ family protein, stabilizes DAL1 by competitively disrupting the DAL1‐DPL1 interaction, thereby counterbalancing the negative regulation by MYC2. This dual regulatory architecture enables conifers to maintain age‐dependent DAL1 expression while integrating growth‐promoting (GA) and defense‐related (JA) signals. Our findings establish a novel GA‐JA crosstalk mechanism in conifers and provide fundamental insights into how long‐lived trees coordinate developmental timing with phytohormone‐mediated environmental adaptation.