OsNAC74 modulates rice growth and salt tolerance via hormone signaling pathways

NAM, ATAF1/2, and CUC2 (NAC) transcription factors are a unique family of plant proteins crucial for regulating plant biotic and abiotic stress responses. This study focuses on OsNAC74, upstream regulatory factors of amino acid permease gene OsAAP6 in rice that influences root regulates root growth, development, and salt tolerance by participating in hormone signaling pathways. OsNAC74 mutations result in a slower germination rate and reduced root length in rice seeds. Under varied salt concentrations, OsNAC74 homozygous mutants exhibited significantly lower survival rates than wild-type plants. Additionally, the expression of salt stress response genes was significantly downregulated in these mutants. The transcriptome sequencing revealed that differentially expressed genes are primarily involved in plant hormone signaling pathways, including abscisic acid, jasmonic acid, and auxin. In the OsNAC74 homozygous mutant roots, auxin concentrations significantly increased, while abscisic acid, gibberellin, and jasmonic acid concentrations significantly decreased. The expression levels of hormone-related genes aligned with these changes in root hormone concentrations. These findings reveal that OsNAC74 can positively regulate salt tolerance in rice and play an important role in rice seed germination and root development. Highlighting its extensive potential for application in rice breeding, providing important genetic resources for molecular design breeding of high-quality, multi-resistant rice varieties.