The Transcription Factor DAL1 Links Age to Reproductive Development Via Regulation of LEAFY Homologs in Conifers

Age-dependent reproductive development is pivotal for plant adaptability and for species perpetuation. While substantial progress has been made in elucidating age-related regulatory mechanisms in angiosperms, the molecular basis of how aging pathway interacts with reproductive development in gymnosperms, particularly conifers, remains elusive. Here, we demonstrate that DEFICIENS-AGAMOUS-LIKE 1 (DAL1), an age marker protein in conifers, binds to and activates two LEAFY (LFY) homologs, PtLEAFY (PtLFY) and PtNEEDLY (PtNLY), in Pinus tabuliformis. Furthermore, PtLFY and PtNLY directly regulate class B and C MADS-box genes, which are essential for specifying reproductive organ identity. Notably, PtLFY exerts a stronger regulatory effect on downstream class B and C genes compared to PtNLY, suggesting potential functional divergence between these two paralogous genes. This study reveals a PtDAL1-mediated regulatory cascade that links aging to reproductive development in conifers. These findings provide insights into the evolutionary conservation and divergence of the reproduction-associated regulatory networks across plant lineages, broadening our understanding of the genetic and molecular mechanisms underlying the reproductive development of gymnosperms.