Molecular Responses of the NAC Gene Family in Acanthus ebracteatus: Involvement in Abiotic Stress Responses and Biosynthesis of Verproside and Verbascoside

The NAC gene family, as a group of plant-specific transcription factors, plays crucial roles in plant growth, development, abiotic stress regulation, and biosynthesis of medicinal components. However, research on this family in the medicinal true mangrove Acanthus ebracteatus remains unreported. In this study, 56 NAC genes (AeNAC01-AeNAC56) were identified from A. ebracteatus transcriptome data, all encoding proteins with the NAM domain. Phylogenetic analysis classified them into two groups, with 51 in Group I and 5 in Group II. Comparative transcriptome analysis of roots, leaves, and flowers, validated by qRT-PCR, revealed lower AeNAC genes expression in leaves, with AeNAC10, AeNAC31, and AeNAC48 showing the lowest levels. Under salt, cold, and waterlogging, AeNAC03/44, /48/56 exhibited differential expression, suggesting their key roles in stress responses. Metabolome analysis further demonstrated that AeNAC14 and AeNAC48 significantly correlated with the biosynthesis of verproside and verbascoside, major bioactive phenythanoid glycodides in A. ebracteatus leaves with anti-inflammatory and antioxidant properties. This study provides insights into the A. ebracteatus NAC gene family, identifying candidate targets for understanding the synergistic regulation of abiotic stress responses and medicinal component biosynthesis, which is significant for optimizing the plant’s growth and medicinal value via genetic engineering.