Genome-Wide Identification of the JAZ Gene Family in Garlic (Allium sativum L.) and the Functional Role of AsJAZ17 in Salt Tolerance

Jasmonate ZIM-domain (JAZ) proteins are pivotal repressors in the jasmonate (JA) signaling pathway, yet their specific roles in garlic (Allium sativum) remain largely unexplored. In this study, 28 AsJAZ genes were identified through a genome-wide analysis. The expansion of this family was primarily driven by whole-genome duplication events, with a significant majority (71.43%) of members belonging to a lineage-specific clade, Subfamily E. While AsJAZ proteins harbor conserved TIFY and Jas domains, they exhibit diverse gene structures and subcellular localization patterns. Notably, AsJAZ17 is strictly localized to the nucleus, whereas AsJAZ16 shows a nucleocytoplasmic distribution, suggesting potential functional compartmentalization within the family. Transcriptomic and qRT–PCR analyses revealed that most AsJAZ genes are responsive to heat, salt, and methyl jasmonate (MeJA) treatments. Protein–protein interaction (PPI) modeling and yeast two-hybrid (Y2H) assays confirmed that AsJAZ17 physically interacts with the MYC2 transcription factor, identifying it as a key regulator within the conserved COI1-JAZ-MYC2 signaling module. Functional validation demonstrated that overexpression of AsJAZ17 in Arabidopsis significantly enhances salt tolerance. This improvement is attributed to an optimized growth-defense trade-off and a reinforced antioxidant defense system, as evidenced by the increased activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), which collectively maintain reactive oxygen species (ROS) homeostasis under stress. These findings provide comprehensive insights into the evolutionary and functional landscape of the garlic JAZ family and identify AsJAZ17 as a promising candidate gene for molecular breeding to improve abiotic stress resilience in Allium crops.