Investigation of the maize (Zea mays L.) JAZ pan-gene family and expression pattern under drought stress conditions

Abstract

The hormone jasmonic acid (JA) regulates plant growth and development, acts as a stress-tolerant signaling molecule, and ensures tolerance to drought stressors. The jasmonate zim-domain (JAZ) functions as a transcriptional repressor by directly interacting with transcription factors, regulating the activity of JA pathway transcription factors when JA signaling is absent. We systematically identified JAZ gene family members using a maize pangenome comprising 26 high-quality genomes. We analyzed evolutionary pressure and structural variation (SV), and reanalyzed public RNA-seq data under drought stress. Sequential expression patterns were further validated using qRT-PCR. In this study, 112 JAZ genes were identified by pan-genomic analysis of 26 high-quality maize genomes, including 12 core genes (present in all 26 lines), 33 non-core genes (in 2–22 lines), 5 near-core genes (in 23–25 lines), and 62 endemic genes (in 1 line). Analysis of Ka/Ks values showed that some varieties were under positive selection for the JAZ19 gene. Among these, 15 ZmJAZ genes had Ka/Ks values < 1, indicating they were subject to purifying selection. There were significant differences in the expression of ZmJAZ19 between genes affected by structural variation (SV) and those not affected by SV. SV altered the conserved structural domains in some varieties, resulting in a significant number of atypical genes. RNA-seq analysis of drought treatment data revealed seven differentially expressed ZmJAZ genes, four of which were core genes. However, atypical genes were identified in numerous response genes across multiple genomes. This study advances our understanding of how ZmJAZ genes contribute to drought adaptation in maize, offering a conceptual framework that links molecular responses to climate-resilient traits essential for sustainable crop production under water-limited conditions in the face of climate change.