Journal Article

Physiological mechanisms of Piriformospora indica- Glycyrrhiza Uralensis Fisch symbiosis in regulating growth and medicinal compound biosynthesis under salt stress

Liu, Peng-fei, Fu, Chen, Tang, Si-ying, Tang, Su-yang, Zhou, Xian-fu, Lou, Bing-gan

2026

Overview

Fisch. is a medicinal plant commonly cultivated in salinized soils, where environmental stress suppresses the accumulation of pharmaceutically active components. To date, only limited studies have examined whether , a root endophytic fungus with growth-promoting and stress-alleviating properties, can improve the salt tolerance and medicinal quality of , particularly at the physiological and transcriptional levels. In this study, we successfully established a symbiotic system between and . To evaluate responses to salt stress, -inoculated and non-inoculated plants were subjected to NaCl treatments at 0, 100, 200, 300, and 350 mM, with 18 biological replicates per treatment. Colonization by was confirmed through microscopic examination and molecular identification. Growth phenotypes, antioxidant enzyme activities, membrane lipid peroxidation levels, chlorophyll-related indices, and the accumulation of key medicinal components were systema4tically quantified in symbiotic across different growth stages. Inoculation with significantly increased plant height, root length, and dry weight by 27.8%, 25.5%, and 52.2%, respectively. The symbiotic association enhanced the activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) by 48.4% and 27.5%, respectively. Although malondialdehyde (MDA) content initially increased by 16.5% due to early fungal colonization, the canopy SPAD value simultaneously increased by 20.3%. These findings suggest that colonization is associated with differential oxidative stress responses between roots and shoots. Furthermore, under the high salt concentration of 300 mM NaCl, the contents of liquiritin and glycyrrhizic acid were markedly increased by 124.7% and 62.5%, respectively. enhanced the accumulation of secondary metabolites by modulating key rate-limiting enzyme genes rather than indiscriminately activating entire metabolic pathways. For example, the symbiont significantly upregulated in triterpenoid saponin biosynthesis and in flavonoid biosynthesis. These transcriptional changes may contribute to alleviating salt-induced constraints on secondary metabolite accumulation. In conclusion, colonization significantly improved growth performance, stress resistance, and medicinal compound accumulation in under salt stress. This study provides a theoretical foundation for improving the cultivation quality of in saline soils.

• Publisher: Frontiers Media SA,Frontiers Media S.A
• Subject: Abiotic stress / Accumulation / Antioxidants / Biomass / Biosynthesis / Colonization / Endophytes / Environmental stress / Enzymatic activity / Experiments / Flavonoids / Flowers & plants / Glycyrrhiza uralensis Fisch / glycyrrhizic acid / Herbal medicine / Homeostasis / Inoculation / Lipid peroxidation / Lipids / liquiritin / Medicinal plants / Metabolic pathways / Metabolism / Metabolites / Original Research / Oxidative stress / Peroxidase / Peroxidation / Phenotypes / phenotypic characteristics / physiological indicators / Physiology / Piriformospora indica / Saline soils / Salinity / Salinity tolerance / Salt / Salt tolerance / Saponins / Secondary metabolites / Seeds / Sodium chloride / Soil stresses / Stress response / Superoxide dismutase / Symbiosis