Comprehensive Identification and Expression Profiling of the NAC Family During Female Cone Development in Torreya grandis

NAC transcription factors are key regulators involved in diverse cellular processes, stress responses, and developmental pathways in plants. However, their roles in female cone development of Torreya grandis, a representative gymnosperm species, remain largely unexplored. In this study, we performed a comprehensive identification and analysis of NAC transcription factors in T. grandis to investigate their potential functions in female cone development. A total of 82 TgNAC members containing conserved NAM domains were identified, distributed unevenly across 11 chromosomes. Phylogenetic analysis with Arabidopsis NACs classified them into 15 groups, with TgNACs represented in 10 groups and showing a notable enrichment in the TERN clade on chromosome 2. Promoter cis-element analysis revealed correlations between regulatory elements and expression patterns. Tissue-specific expression profiling indicated clear functional specialization, with some TgNACs showing no detectable expression in the examined tissues. During female cone development, several TgNACs were highly expressed in the early stages, whereas TgNAC72, TgNAC76 and TgNAC82 were upregulated during the latter stages. Among these, TgNAC72 exhibited the highest overall expression level. Subcellular localization confirmed TgNAC72 is localized in the nucleus. Dual-luciferase assays further demonstrated that TgNAC72 activates the TgBGLU13 promoter, suggesting its role in starch and sucrose metabolism. Collectively, these findings provide novel insights into the regulatory involvement of TgNACs in reproductive organ development.