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Rhizosphere regulation by pioneer plants reprograms microbial assembly and drives soil functional recovery in contaminated mine tailings
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DOI：10.1007/s11104-026-08957-y.png)
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Abstract
En 中文
Mine tailings represent a global restoration challenge due to their dual stress of heavy metal toxicity and extreme nutrient scarcity. The mechanisms driving their ecological recovery, however, remain poorly understood. This study investigated a Cd-As co-contaminated tailing site to elucidate how pioneer plants are associated with the initiation of functional reconstruction. Three pioneer plants with stable natural colonization, Miscanthus floridulus, Bidens pilosa and Solanum nigrum, were selected to collect rhizosphere soil and root exudates, with bare tailings as control. Soil physicochemical properties, microbial diversity, and root exudate metabolomes were analyzed. Three Pioneer plant colonization significantly reduced rhizosphere Cd and As concentrations by 33.23–64.70% and 22.75–42.84%, respectively, and increased soil organic matter (SOM) and total nitrogen by 1.87–3.57 and 4.81–7.52 fold compared to bare tailings. Among the three species, M. floridulus and B. pilosa exhibited stronger metal stabilization effects. Partial least squares path modeling identified SOM as the single most critical correlate of soil functionality, with fungal diversity acting as the pivotal correlate linking plant carbon inputs to functional recovery. We emphasize that this association reflects correlation and predictive importance, not causation. Most likely, SOM and microbial communities are mutually reinforcing. Therefore, we refer to SOM as a “central correlate” or “key node” in the recovery process rather than an unequivocal “driver”. Mechanistically, pioneer plants modulate the chemical quality of their root exudates (particularly lipids, phenylpropanoids, and organic acids), which is associated with intensified deterministic selection pressures. This process correlates with a restructuring of microbial community assembly, favoring stress-tolerant, functionally specialized taxa while simplifying overall community structure. Based on these three pioneer species, we propose a function-oriented recovery pathway centered on SOM accumulation and fungus-associated carbon transformation. This work offers a complementary perspective to the conventional focus on diversity metrics, warranting further testing across a broader range of pioneer plants, providing a new mechanistic framework for the long-term, low-intervention restoration of contaminated ecosystems.
Keywords:
Heavy metal
Ecological restoration
Rhizosphere microbiome
Root exudates
Soil organic matter
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