This study presents a comprehensive analysis of NAC family genes in Oryza sativa (rice) and Arabidopsis thaliana. The NAC domain, originally identified in petunia NAM and Arabidopsis ATAF1, ATAF2, and CUC2, is a conserved region in plant-specific transcriptional regulators. The researchers identified 75 predicted NAC proteins in rice and 105 in Arabidopsis, classifying them into two main groups and 18 subgroups based on sequence similarity. The NAC domains showed some differences in amino acid sequences between the two species. Additionally, 13 common sequence motifs were found in the C-terminal regions of predicted NAC proteins, likely related to NAC domain structures. The study also investigated the transcriptional activation regions (TARs) of NAC family proteins, identifying 13 common motifs. These motifs were found in various subgroups, suggesting that TARs are conserved in parallel with NAC domain structures. The analysis revealed that NAC family proteins are involved in various plant developmental and morphogenic systems, including shoot apical meristem formation, organ separation, and stress response. The results indicate that NAC family genes are plant-specific transcriptional regulators, and their functions are related to their structural characteristics. The study provides insights into the relationship between the structure and function of NAC family proteins, and highlights the importance of NAC domains and TARs in determining their functions. The findings will aid further functional analysis of NAC family genes in plants.This study presents a comprehensive analysis of NAC family genes in Oryza sativa (rice) and Arabidopsis thaliana. The NAC domain, originally identified in petunia NAM and Arabidopsis ATAF1, ATAF2, and CUC2, is a conserved region in plant-specific transcriptional regulators. The researchers identified 75 predicted NAC proteins in rice and 105 in Arabidopsis, classifying them into two main groups and 18 subgroups based on sequence similarity. The NAC domains showed some differences in amino acid sequences between the two species. Additionally, 13 common sequence motifs were found in the C-terminal regions of predicted NAC proteins, likely related to NAC domain structures. The study also investigated the transcriptional activation regions (TARs) of NAC family proteins, identifying 13 common motifs. These motifs were found in various subgroups, suggesting that TARs are conserved in parallel with NAC domain structures. The analysis revealed that NAC family proteins are involved in various plant developmental and morphogenic systems, including shoot apical meristem formation, organ separation, and stress response. The results indicate that NAC family genes are plant-specific transcriptional regulators, and their functions are related to their structural characteristics. The study provides insights into the relationship between the structure and function of NAC family proteins, and highlights the importance of NAC domains and TARs in determining their functions. The findings will aid further functional analysis of NAC family genes in plants.