A multi-faceted mechanism of Cladosporium cladosporioides-mediated arsenic reduction in Panax notoginseng taproots: Insights from integrated multi-omics and microbiome analyses

Panax notoginseng, a medicinally important perennial plant native to Yunnan Province, China, faces safety challenges due to arsenic (As) accumulation in its tissues from contaminated soils, compromising its safe use in medicine and food. This study aimed to elucidate how the dark septate endophyte Cladosporium cladosporioides reduces As accumulation in P. notoginseng taproots through a multi-faceted approach investigating growth promotion, metabolite synthesis, rhizosphere diversity, transcriptomics, and proteomics. Results demonstrated C. cladosporioides inoculation enhanced plant biomass, photosynthetic efficiency, saponin content, and antioxidant enzyme activity, while reducing As accumulation in taproots by inhibiting the transport of As from fibrous roots to taproots. The fungus also reshaped the rhizosphere bacterial community, enriching beneficial and stress-tolerant taxa such as Bradyrhizobium, Sphingomonas, and Pseudomonas. Integrated transcriptomic and proteomic analyses further revealed the upregulation of key genes and proteins associated with antioxidant defense, As transport, and detoxification processes. Structural equation modeling confirmed that improved soil properties, beneficial assembly of bacterial communities, enhanced photosynthetic capacity, and activated saponin biosynthesis collectively promote plant growth while lowering As accumulation in the taproot. Overall, C. cladosporioides reduces As accumulation in P. notoginseng taproots via coordinated physiological, molecular, and microbial mechanisms, providing a sustainable cultivation strategy for As-contaminated soils.