The NAC Transcription Factor PtARN Governs Age-Related Wood Formation via a PtDAL1-PtARN Regulatory Cascade in Chinese Pine.
Conifers exhibit distinct age-related transitions in wood development, yet the molecular mechanisms governing these changes remain poorly characterized. Here, we integrate multi-omics and functional analyses to unravel a transcriptional regulatory network underlying age-related wood formation in Chinese pine (Pinus tabuliformis). Cross-sectional and Raman microspectroscopy analyses revealed age-dependent enhancement of lignification and carbohydrate deposition in secondary xylem, coinciding with increased pith proportion. Temporal transcriptome profiling identified PtARN (AGE-RELATED NAC TRANSCRIPTION FACTOR) as a key age-correlated regulator, whose expression is directly activated by the conserved age timer PtDAL1 through promoter binding. We conducted a genome-wide identification of secondary cell wall biosynthesis pathway genes in P. tabuliformis, and genome-wide DNA affinity purification analysis uncovered that PtARN direct binding to promoters of 189 secondary cell wall biosynthesis genes. Strikingly, PtARN represses PtMYB162, a lignin biosynthesis suppressor, forming a regulatory cascade to fine-tune lignification. Collectively, our work establishes PtARN as a master regulator orchestrating age-dependent secondary cell wall deposition and lignification in the secondary xylem of Chinese pine, and delineates a previously uncharacterized PtDAL1-PtARN-mediated molecular regulatory network in P. tabuliformis. These findings significantly advance our understanding of the molecular regulatory network underlying wood formation in conifers, and bridging developmental timing with cell wall remodelling, and provide a robust framework for conifer-specific wood formation studies.