Multi-Omics Analysis of the Enhancement of Bioactive Components in Glycyrrhiza uralensis Fisch. through Combined Inoculation with Rhizobium and PGPR under Salt Stress

Background and objective Licorice, an important forage crop widely cultivated worldwide, faces increasing scarcity of wild resources, making artificial cultivation the primary means of market supply. Salt stress negatively impacts the quality and yield of licorice, while microbial inoculation can not only effectively alleviate the damage caused by salt stress but also enhance its quality. To elucidate the response mechanism of licorice to salt stress, this study investigated the physiological, transcriptomic, and metabolomic changes under salt stress. Results The results showed that the combined inoculation group exhibited significant increases in osmotic substance and chlorophyll content. Transcriptome and metabolome sequencing analysis, along with pathway validation, identified 34, 76, and 54 differentially expressed genes (DEGs) in the CK vs CKNaCl, GM9ZNaCl vs CKNaCl, and GM10NaCl vs CKNaCl groups, respectively. These genes were primarily enriched in pathways such as ABC transporters, oxidative phosphorylation, plant hormone signal transduction, and jasmonic acid biosynthesis. The contents of metabolites including linoleic acid, amino acids, and jasmonic acid in licorice were significantly increased. Conclusion It is inferred that combined inoculation may enhance the osmotic regulation capacity and antioxidant defense ability of G. uralensis roots under salt stress, activate phytohormone signaling pathways such as jasmonic acid, and thereby coordinately regulate the expression of related functional genes, effectively improving the salt tolerance of G. uralensis and promoting the synthesis of secondary metabolites. This study provides an important theoretical basis for utilizing microbial agents to improve the growth of medicinal plants in saline-alkali soils.