Abstract: To explore phytohormone expression in the roots of transplanted Kandelia obovata and analyze its strategies for coping with environmental stress through hormone regulation. Hormone expression was detected in the roots of Kandelia obovata from both natural habitat JGJ-C and the artificial transplant KQW-E at Qinzhou Port by utilizing LC-MS/MS metabolomics technology. The metabolic characteristics and network interactions were analyzed, and the main metabolic pathways were also determined through KEGG annotation.A total of 62 phytohormones were detected in the roots of the two types of Kandelia obovata, with 28 exhibiting significant differences (16 upregulated and 12 downregulated). In the KQW-E group, stress-related hormones such as abscisic acid (ABA) and its glucose ester (ABA-GE), as well as conjugated auxin (IAA-Glc), were significantly downregulated, while growth-promoting hormones like zeatin (cZR) and jasmonic acid precursor (H2JA) were significantly upregulated. KEGG pathway enrichment analysis revealed that the differential hormones were primarily enriched in terpenoid metabolism, plant hormone signal transduction, and secondary metabolite synthesis pathways. Kandelia obovata dynamically balances active hormone levels through the synergistic regulation of multiple hormones, including ABA, auxin, jasmonic acid, and cytokinin, thereby downregulating stress responses and upregulating growth-related metabolism. This optimization of resource allocation enhances transplant adaptability. This study provides a theoretical basis for hormonal regulation and ecological restoration in the artificial transplantation of mangroves.

Key words: Kandelia obovata, LC-MS/MS, plant hormones, metabolomics, stress response, multi-hormone synergistic regulation