Rhizosphere Microbiota and Soil Nutrients Shape Fruit Lignan Composition of Schisandra chinensis Across Temperate Cultivation Sites in Northeast and Northwest China

<i>Schisandra chinensis</i> (Turcz.) Baill. (S. <i>chinensis</i>) is a widely used medicinal plant whose therapeutic efficacy is closely linked to its lignan content. While previous studies have focused on soil fertility and cultivar variation, the interplay among soil nutrients, rhizosphere microbiota, and lignan accumulation remains poorly understood. This study investigated <i>S. chinensis</i> grown across 20 cultivation sites to elucidate the relationships among soil nutrient profiles, fruit lignan composition, and rhizosphere microbial communities. Six major lignans were quantified using HPLC, soil nutrients were analyzed via standard chemical assays, and rhizosphere bacterial communities were profiled using 16S rRNA sequencing. Multivariate analyses revealed significant variation in soil properties and lignan content across sites. Notably, available phosphorus, organic matter, and total nitrogen showed strong correlations with specific lignan compounds. From the top 50 taxa ranked by relative abundance at the genus level, 18 bacterial genera associated with lignan components were identified. Among them, <i>Mycobacterium</i>, <i>Arthrobacter</i>, <i>Haliangium</i>, <i>Bacillus</i>, <i>Sphingomonas</i>, <i>Rhodanobacter</i>, <i>Ellin6067</i>, <i>Bradyrhizobium</i>, <i>Pseudolabrys</i>, <i>Chujaibacter</i>, <i>Gemmatimonas</i>, <i>Bryobacter</i>, <i>MND1</i>, <i>Candidatus Sollbacter</i>, <i>Gaiella</i>, <i>Paenibacillus</i>, <i>RB41</i>, and <i>Candidatus_Udaeobacter</i> were significantly associated with lignan levels, suggesting potential microbial involvement in lignan biosynthesis. These findings provide insights into the ecological factors shaping the medicinal quality of <i>S. chinensis</i> and offer a foundation for targeted cultivation and breeding strategies.