Genome-Wide Analysis of NAC Transcription Factor Gene Family in Morus atropurpurea

The NAC (NAM/ATAF1/2/CUC2) transcription factors are pivotal regulators in plant development and stress responses. Despite the extensive studies on the NAC gene family across various plant species, the characterization of this gene family in mulberry (Morus atropurpurea) remains unexplored. Here, we conducted a genome-wide identification and characterization of the NAC gene family in M. atropurpurea. A total of 79 MaNAC genes were identified and classified into 20 subgroups, displaying an uneven distribution across the 14 chromosomes. The structural analysis found that most MaNAC genes possess at least three exons and contain the conserved NAC domain and characteristic motifs at the N-terminus. Eleven collinear gene pairs were identified in M. atropurpurea genome. Interspecies collinearity analysis demonstrated a closer evolutionary relationship between M. atropurpurea and Populus trichocarpa, supported by the identification of 116 collinear gene pairs. Expression profiling revealed dynamic changes in the transcript levels of most MaNAC genes during mulberry fruit maturation. Notably, the eight MaNAC members from the OsNAC7 subfamily exhibited tissue-specific expression patterns. A significant proportion of MaNAC genes displayed varying degrees of responsiveness to drought stress and sclerotium disease. MaNAC12, MaNAC32, MaNAC44 and MaNAC67 emerged as the most highly responsive candidates. Overexpression of MaNAC69 enhanced drought tolerance in Arabidopsis. These findings provide a robust foundation for future functional studies and mechanistic investigations into the roles of the NAC gene family in M. atropurpurea, offering insights into their contributions to development and stress adaptation.