JAZ Gene Family in Camellia nitidissima: Genome-Wide Identification and Expression Analysis During Flower Development and Hormone Treatments

JAZ (Jasmonate ZIM-Domain) proteins are key negative regulators of the jasmonic acid (JA) signaling pathway and are involved in various plant growth, development, and stress regulation. However, the functions of the JAZ gene family in Camellia nitidissima remain poorly understood. Here, ten CnJAZ genes were identified at the genome-wide level, encoding 134–398 amino acids and unevenly distributed across eight chromosomes. All CnJAZs were predicted to localize to the nucleus. Based on phylogenetic and structural analyses, the ten CnJAZs were classified into five subfamilies, with members of the same subfamily sharing similar exon–intron structures. Collinearity analysis with Arabidopsis thaliana and Malus domestica suggests that the JAZ gene family shares a common ancestor. Promoter analysis revealed cis-acting elements responsive to light, methyl jasmonate (MeJA), and anaerobic stress. Transcriptome profiling showed that most CnJAZs exhibit tissue- and development-specific expression, particularly during flower development and organ formation. RT-qPCR confirmed that MeJA and gibberellin (GA3) significantly induced the expression of CnJAZ, whereas ethylene (ETH) treatment up-regulated CnJAZ3 and CnJAZ5 by 80-fold after three hours. These findings highlight their important roles in growth, development, and hormonal regulation in C. nitidissima, laying a foundation for functional studies.