Identification and Expression Analysis of NAC Transcription Factors Related to Rust Resistance in Foxtail Millet

Foxtail millet (<i>Setaria italica</i>), a vital cereal crop in China, serves as both a staple food and forage source but is threatened by rust disease caused by <i>Uromyces setariae-italicae</i> (<i>Usi</i>), leading to severe yield and quality losses. The NAM, ATAF1/2, and CUC2 (NAC) transcription factor family represents one of the largest plant-specific regulatory gene families, playing pivotal roles in development and stress responses. However, the functional relevance of NAC genes in foxtail millet's defense against this pathogen remains unexplored. Here, we systematically analyzed 33 <i>SiNAC</i> genes from the foxtail millet genome. Phylogenetic analysis classified these genes into 11 subgroups, while chromosomal mapping localized them to nine chromosomes unevenly. Promoter analysis identified stress- and plant hormone-related <i>cis</i>-elements, suggesting functional diversity. Expression profiling analysis showed that most <i>SiNAC</i> genes exhibit tissue-specific expression patterns. Quantitative real-time PCR (qRT-PCR) results indicated that 30 genes responded to <i>Usi</i> infection, with 17 showing a strong association with rust resistance. Three resistance-associated genes demonstrated transactivation activity and nuclear localization, indicating their regulatory function in defense responses. This study provides both mechanistic insights into <i>SiNAC</i>-mediated rust resistance and potential targets for molecular breeding in foxtail millet.