Transcriptome Analysis and Functional Validation of JAZ Subfamily Genes of Sesuvium portulacastrum Under Salt and Cadmium Stresses

Plants are frequently exposed to various abiotic stresses during their growth and development. S. portulacastrum possesses inherent tolerance to salinity and heavy metals, yet the underlying molecular mechanisms remain poorly understood. In this study, we performed a comprehensive analysis of S. portulacastrum by integrating full-length transcriptome sequencing and RNA sequencing (RNA-seq) under salt stress conditions. Transcriptome analysis identified 2839 and 1813 DEGs in leaves and 7328 and 754 DEGs in roots at 7 and 14 ds after NaCl treatment, respectively. Pathway enrichment analysis indicated that these DEGs were significantly enriched in pathways associated with Photosynthesis, plant hormone signal transduction, Linoleic acid metabolism, chlorophyll metabolism, and amino acid metabolism. Expression profiling showed that JAZ subfamily genes were significantly upregulated in both leaves and roots under salt and Cd stress. We cloned SpJAZ1, SpJAZ5, and SpJAZ7, and generated their overexpression lines in Arabidopsis. Physiological assays demonstrated that overexpression of SpJAZ1, SpJAZ5, and SpJAZ7 reduced hydrogen peroxide content by 29.07%, 20.62%, and 19.79%, respectively, and lowered the reduction in chlorophyll content (0.12, 0.15, and 0.17 μg/mL vs. 0.22 μg/mL). Meanwhile, proline content was increased in these lines (2.34, 2.08, and 2.05 μg/mL vs. 1.53 μg/mL), alongside enhancements in root length, lateral root number, and water content under salt stress. Importantly, these overexpression lines displayed a similar functional trend under Cd stress. Collectively, our results reveal potential crosstalk between the JA signaling pathway and stress mitigation pathways in S. portulacastrum in response to salt and Cd stresses.