Salt Stress Enhances Bioactive Compound Accumulation in Glycyrrhiza inflata: Integrated Transcriptomics and Physiological Analysis Reveals Germplasm-Specific Adaptation Mechanisms

Bo Zhu¹Linyuan Cheng¹Nana Shi¹Pi Zheng Chen¹Yiyuan Qu²FEI GUO³hua Yao^1*Haitao Shen^1*

• ¹Shihezi University, Shihezi, China
• ²Department of Industry and Information Technology of Xinjiang Uygur Autonomous Region, Urumqi 830000, China, Urumchi, China
• ³School of Life Sciences, Zhuhai College of Science and Technology, Zhuhai 519040, China, Zhuhai, China

Glycyrrhiza inflata Batal., primarily distributed in the saline-alkali deserts of southern Xinjiang, China, is a halophytic plant rich in bioactive compounds such as flavonoids and triterpenoids. It holds significant potential for applications in pharmaceuticals, food, health products, and cosmetics.Its cultivation offers dual benefits: economic returns and saline-alkali soil remediation. This study investigated 29 distinct provenance of G. inflata collected from various locations across Xinjiang.Key agronomic traits and the content of bioactive compounds in the underground parts of one-yearold plants cultivated in severely saline-alkali soils were measured to evaluate inter-germplasm variation in bioactive compound content and saline-alkali tolerance. Subsequently, four germplasms exhibiting contrasting quality and salt tolerance were selected for controlled laboratory salt stress treatment (150 mM NaCl). The effects on seed germination, root bioactive compound content, endogenous hormone levels, and key physiological and biochemical indices were analyzed.Integrated analysis of salt stress transcriptomic data and Weighted Gene Co-expression Network Analysis (WGCNA) was performed. This involved expression clustering and enrichment analysis of differentially expressed genes (DEGs) to elucidate the impact of salt stress on the expression of genes associated with bioactive compound biosynthesis (particularly flavonoids), endogenous hormone pathways, and key enzymes in flavonoid production. Results indicate that germplasms with superior stress tolerance possess higher and more stable levels of antioxidant enzymes. In response to stress, these resilient germplasms modulate hormone signaling, notably upregulating abscisic acid (ABA) and downregulating auxin (IAA), thereby reallocating resources towards defense mechanisms.Crucially, salt stress was identified as an effective means to enhance the accumulation of bioactive compounds in G. inflata. Transcriptomic analysis revealed substantial divergence in post-stress gene expression patterns among germplasms, implicating pathways such as plant hormone signal transduction, flavonoid biosynthesis, and phenylpropanoid metabolism.This research establishes a foundation for breeding high-quality G. inflata germplasms adapted to desert saline-alkali soils and provides insights into the molecular mechanisms regulating the synthesis and accumulation of its valuable compounds.