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Background and aims <p>Cadmium (Cd) contamination in soils threatens medicinal plants by hindering growth and accumulating toxic metals, which can disrupt bioactive compound synthesis. Dark septate endophytes (DSE), common in stressed ecosystems, offer a microbiome-based approach to boost plant resilience, but their dual role in mitigating Cd toxicity and enhancing medicinal quality is not fully understood.</p> Methods <p>In this study, a pot experiment was conducted with <i>Astragalus mongholicus</i> inoculated with two DSE strains, <i>Neocamarosporium phragmitis</i> (<i>Np</i>) and <i>Alternaria tellustris</i> (<i>At</i>), under Cd stress at 0, 5, 10, and 15&#xa0;mg/kg.</p> Results <p>DSE inoculation significantly improved root morphology and biomass under Cd stress, with <i>At</i> exhibiting stronger effects at moderate to high Cd levels. Physiologically, DSE enhanced antioxidant responses, increasing proline, soluble sugars, ascorbic acid, and peroxidase activity, while catalase activity was suppressed under high Cd stress, reflecting strain-specific regulation. DSE also increased rhizosphere pH and transformed Cd from exchangeable forms to more stable carbonate-bound, Fe–Mn oxide-bound, and residual fractions, reducing Cd bioavailability. Soil pH and catalase correlated positively with residual Cd, while available phosphorus negatively correlated with exchangeable Cd. Structural equation modeling indicated that <i>Np</i> reduced root Cd mainly through soil modification, whereas <i>At</i> directly enhanced plant physiological tolerance. Notably, DSE increased astragaloside content only under no or low Cd stress (≤ 5&#xa0;mg/kg), with no effect under higher stress.</p> Conclusions <p>Specific DSE strains can synergistically stabilize Cd and improve plant resilience through soil–plant interactions, supporting safer production of medicinal plants within a defined Cd threshold.</p> Graphical Abstract <p></p>

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Mediating cadmium tolerance and astragaloside accumulation through dark septate endophytes (dse)-induced reshaping of the soil–plant continuum in Astragalus mongholicus

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Yiling Zuo,
  • Xinyu Liu,
  • Zhengyu Zhu,
  • Nannan Zhang,
  • Jiao Wang,
  • Chao He,
  • Xueli He

摘要

Background and aims

Cadmium (Cd) contamination in soils threatens medicinal plants by hindering growth and accumulating toxic metals, which can disrupt bioactive compound synthesis. Dark septate endophytes (DSE), common in stressed ecosystems, offer a microbiome-based approach to boost plant resilience, but their dual role in mitigating Cd toxicity and enhancing medicinal quality is not fully understood.

Methods

In this study, a pot experiment was conducted with Astragalus mongholicus inoculated with two DSE strains, Neocamarosporium phragmitis (Np) and Alternaria tellustris (At), under Cd stress at 0, 5, 10, and 15 mg/kg.

Results

DSE inoculation significantly improved root morphology and biomass under Cd stress, with At exhibiting stronger effects at moderate to high Cd levels. Physiologically, DSE enhanced antioxidant responses, increasing proline, soluble sugars, ascorbic acid, and peroxidase activity, while catalase activity was suppressed under high Cd stress, reflecting strain-specific regulation. DSE also increased rhizosphere pH and transformed Cd from exchangeable forms to more stable carbonate-bound, Fe–Mn oxide-bound, and residual fractions, reducing Cd bioavailability. Soil pH and catalase correlated positively with residual Cd, while available phosphorus negatively correlated with exchangeable Cd. Structural equation modeling indicated that Np reduced root Cd mainly through soil modification, whereas At directly enhanced plant physiological tolerance. Notably, DSE increased astragaloside content only under no or low Cd stress (≤ 5 mg/kg), with no effect under higher stress.

Conclusions

Specific DSE strains can synergistically stabilize Cd and improve plant resilience through soil–plant interactions, supporting safer production of medicinal plants within a defined Cd threshold.

Graphical Abstract