CONSTANS-Like and SHORT VEGETATIVE PHASE-Like Genes Coordinately Modulate TERMINAL FLOWER 2 to Control Dormancy Transitions in Pinus tabuliformis.

With global climate change, understanding how conifers manage seasonal dormancy is increasingly important. This study explores the physiological and molecular processes controlling dormancy transitions in P. tabuliformis, a key species in northern China. Using dormancy simulations and Time-Ordered Gene Co-Expression Network (TO-GCN) analysis, we identified low temperature, rather than photoperiod, as the primary trigger for dormancy release. The PtTFL2 gene functions as both an environmental sensor and dormancy marker, regulated by cold-dependent and independent pathways involving the photoperiod-responsive PtCOL1 and PtSVP-like (SVL) genes. During the autumn-to-winter transition, PtSVL controls PtTFL2 transcription, forming a regulatory complex to fine-tune dormancy. PtCOL1 also directly regulates PtTFL2 and indirectly modulates it by affecting PtSVL expression. The CO-TFL module controls fall dormancy (ecodormancy), while the SVP-TFL module manages the shift to endodormancy in winter. These findings reveal dual regulatory pathways governing dormancy in conifers, offering insights into their adaptation to cold environments and laying the foundation for further research into dormancy mechanisms in gymnosperms.