Paraboremia selaginellae enhances Salvia miltiorrhiza growth and cadmium tolerance via modulating root architecture and cadmium speciation in contaminated environments

Summary

A beneficial fungus called Paraboremia selaginellae was found to help medicinal plants grow better in soil contaminated with cadmium, a toxic heavy metal. When this fungus colonizes plant roots, it reduces how much cadmium the plant absorbs and improves the soil’s nutrient content. This natural approach offers a promising solution for growing medicinal plants safely in polluted soils without expensive chemical treatments.

Background

Heavy metal pollution, particularly cadmium (Cd) contamination in soil, poses a serious threat to plant growth and agricultural production. Dark septate endophytes (DSEs) are fungi that colonize plant roots in heavy metal-polluted habitats and have demonstrated capacity to improve plant tolerance to heavy metals. However, the mechanisms by which DSEs enhance medicinal plant growth in Cd-contaminated environments remain poorly understood.

Objective

This study investigated the growth and Cd tolerance mechanisms of Paraboremia selaginellae (a DSE strain) and its effects on Salvia miltiorrhiza (a medicinal plant) in Cd-contaminated soil. The research aimed to determine whether P. selaginellae could reduce Cd accumulation in plants and alter soil Cd speciation.

Results

P. selaginellae demonstrated high Cd tolerance and accumulated Cd in its mycelium while increasing melanin and osmotic substances. Inoculation significantly increased root biomass (30-42% improvement), improved soil nutrient content (nitrogen, urease, alkaline phosphatase), and reduced plant Cd accumulation. P. selaginellae inoculation decreased the proportion of highly toxic exchangeable Cd forms in soil while increasing less bioavailable residual forms.

Conclusion

Dark septate endophytes, specifically P. selaginellae, effectively enhance S. miltiorrhiza growth and Cd tolerance through modulation of root architecture, soil nutrient availability, and Cd speciation. The exploitation of DSE resources represents a promising approach for improving medicinal plant cultivation in heavy metal-contaminated soils.
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