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Background and Aims <p>Cadmium (Cd) pollution and atmospheric nitrogen (N) deposition are increasing concurrently, particularly in urban soils. Plant growth–promoting rhizobacteria (PGPR) may mitigate Cd stress, but their effectiveness under N enrichment remains unclear. We tested whether <i>Pseudomonas fluorescens</i> (Pf) alleviates Cd + N stress in <i>Ginkgo biloba</i> L. and whether this response is associated with root cell-wall traits, N-assimilation metabolism, and antioxidant defenses.</p> Methods <p>Seedlings were exposed to Cd addition, N addition, or both, with or without Pf inoculation. Root cell-wall polysaccharides (pectin, hemicellulose 1 and 2), pectin methylesterase (PME) activity, and leaf nitrate reductase (NR) and glutamine synthetase (GS) activities, together with antioxidant/ROS-related indicators, glutathione (GSH) and phytochelatins (PCs), were quantified using spectrophotometric assays. Cd content in different tissues was determined by inductively coupled plasma mass spectrometry (ICP-MS). Gene expression was assessed by quantitative real-time PCR (qRT-PCR).</p> Results <p>Under Cd + N stress, <i>P. fluorescens</i> reduced Cd accumulation in stems and leaves by 45.23% and 59.57%, respectively, improved pigment status and antioxidant responses, and increased root pectin content and PME activity. Selected antioxidant-related transcripts (e.g., <i>Fe-SOD, APX</i>), GSH, and PCs also increased compared with non-inoculated controls.</p> Conclusions <p>These results suggest that <i>P. fluorescens</i> reduces Cd translocation and alleviates oxidative damage during short-term Cd + N exposure. Changes in root cell-wall traits provide indirect evidence that cell-wall modification may contribute to Cd retention; however, direct measurements of cell-wall Cd partitioning and longer-term validation are still required.</p>

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Pseudomonas fluorescens Mitigates Cadmium Stress in Ginkgo biloba L. under nitrogen enrichment by reducing Cd translocation and modifying root cell-wall composition

  • 期刊论文

  • 发表日期：

    2026年7月2日

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  • Jinmeng Li,
  • Jian Zhao,
  • Rongrong Gu,
  • Xiaoqian Wang,
  • Yanan Ruan

摘要

Background and Aims

Cadmium (Cd) pollution and atmospheric nitrogen (N) deposition are increasing concurrently, particularly in urban soils. Plant growth–promoting rhizobacteria (PGPR) may mitigate Cd stress, but their effectiveness under N enrichment remains unclear. We tested whether Pseudomonas fluorescens (Pf) alleviates Cd + N stress in Ginkgo biloba L. and whether this response is associated with root cell-wall traits, N-assimilation metabolism, and antioxidant defenses.

Methods

Seedlings were exposed to Cd addition, N addition, or both, with or without Pf inoculation. Root cell-wall polysaccharides (pectin, hemicellulose 1 and 2), pectin methylesterase (PME) activity, and leaf nitrate reductase (NR) and glutamine synthetase (GS) activities, together with antioxidant/ROS-related indicators, glutathione (GSH) and phytochelatins (PCs), were quantified using spectrophotometric assays. Cd content in different tissues was determined by inductively coupled plasma mass spectrometry (ICP-MS). Gene expression was assessed by quantitative real-time PCR (qRT-PCR).

Results

Under Cd + N stress, P. fluorescens reduced Cd accumulation in stems and leaves by 45.23% and 59.57%, respectively, improved pigment status and antioxidant responses, and increased root pectin content and PME activity. Selected antioxidant-related transcripts (e.g., Fe-SOD, APX), GSH, and PCs also increased compared with non-inoculated controls.

Conclusions

These results suggest that P. fluorescens reduces Cd translocation and alleviates oxidative damage during short-term Cd + N exposure. Changes in root cell-wall traits provide indirect evidence that cell-wall modification may contribute to Cd retention; however, direct measurements of cell-wall Cd partitioning and longer-term validation are still required.